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1、ISTATE OF BLUE CARBON ECOSYSTEMS FOR CLIMATE ACTIONIN ASIA AND THE PACIFICState of Blue Carbon Ecosystems for Climate Action in Asia and the PacificII*The designations employed and the presentation of material on this map do not imply the expression of any opinion whatsoever on the part of the Secre

2、tariat of the United Nations concerning the legal status of any country,territory,city or area or of its authorities,or concerning the delimitation of its frontiers or boundaries.The shaded areas of the map indicate ESCAP members and associate members.*DISCLAIMERThis publication may be reproduced in

3、 whole or in part for educational or non-profit purposes without special permission from the copyright holder,provided that the source is acknowledged.The ESCAP Publications Office would appreciate receiving a copy of any publication that uses this publication as a source.No use may be made of this

4、publication for resale or any other commercial purpose whatsoever without prior permission.Applications for such permission,with a statement of the purpose and extent of reproduction,should be addressed to the Secretary of the Publications Board,United Nations,New York.The secretariat does not guara

5、ntee the accuracy of data.The designations employed and the presentation of material on all maps in this publication do not imply the expression of any opinion on the part of the Secretariat of the United Nations or authors concerning the legal status of any country,territory,city or area or of its

6、authorities,or concerning the delimitation of its frontiers or boundaries.United Nations publication,2024 All rights reservedST/ESCAP/3124Photo Credits:Pixabay.This publication should be cited as United Nations Economic and Social Commission for Asia and the Pacific(2024).State of Blue Carbon Ecosys

7、tems for Climate Action in Asia and the Pacific.United Nations publication.State of Blue Carbon Ecosystems for Climate Action in Asia and the PacificIII1.Note:The C-CO2 Conversion Factor is 3.67(IPCC,2007).Executive SummaryIn the Asia-Pacific region,there is a significant demand for nature-based sol

8、utions.This region has contributed over 30 per cent of all global nature-based credits,equivalent to a total of 85 million tons of carbon dioxide(CO2).However,investments in nature-based solutions remain restricted,with a predominant focus on terrestrial ecosystems,such as forests.While coastal ecos

9、ystems,specifically mangroves,coral reefs and seagrass,play a critical role in climate change and environmental policies in the region,the integration of blue carbon into the NDCs(Nationally Determined Contributions)of the regions countries presents a series of challenges.In this context,this report

10、 assesses the coverage of key coastal ecosystems(mangroves,coral reefs and seagrass)and their conservation and restoration potential.The need for better data remains a consistent challenge and presents important constraints to this work.This assessment and the notional targets for mangrove restorati

11、on presented are intended to support national dialogue among stakeholders and underline the need for country-driven assessments,where they do not exist.Seizing these opportunities requires further research,enhanced policy and technical guidance,capacity-building,and improved coordination among relev

12、ant actors.MangrovesMangroves are a prominent feature in tropical and subtropical coastal areas,and covered approximately 147,359 km2globallyin2020,withthemajority(51percent)foundintheAsia-Pacificregion.The Asia-Pacific region has 7.48 million hectares of mangroves,which provide ecosystem services v

13、alued at US$1.5 trillion annually.In Indonesia alone,mangroves are essential to an estimated 893,000 small-scale fishers.MangrovecoverisdecliningfastestintheAsia-Pacificregionascomparedtoallglobalregions.Asia and the Pacific recorded a net decline in mangrove cover of 3,338 km2(63 per cent of the gl

14、obal loss)between 1996 and 2020.However,the rate of loss has decreased in the past decade.Both,climate change and other human activities are driving mangrove loss in the Asia-Pacific region.The primary driver of mangrove loss in the region is the expansion of agriculture into mangrove habitats,follo

15、wed by a rapid increase in brackish water aquaculture.Inthelast25years,theAsia-Pacificregionhasbeenresponsibleforasubstantialgloballossofcarbonstored in mangrove forests,accounting for 70 per cent of the total.This amounts to a net loss of 98 Mt of carbon.1 Indonesia experienced the highest losses,f

16、ollowed by Australia.However,the region also gained mangroves which might store 86 Mt of carbon(equivalent to potential emissions of 314 MtCO2),with Bangladesh in the lead in increasing net carbon storage in its mangrove forests.The contrast between mangrove losses in Indonesia and gains in Banglade

17、sh is likely attributable to the varying degrees of mangrove protection within these countries.In Bangladesh,a significant 88 per cent of mangroves are under protection,whereas only 25 per cent are under protection in Indonesia.A notional mangrove restoration target of 1350 km2by2030isproposedforthe

18、Asia-Pacificregion.Mangrove loss is a serious problem in the region,but there is also a great deal of potential for restoration.A notional target(or,better threshold)of restoring 1350 km2 of mangrove forest by 2030 has been identified in this study.This would recover 70 per cent of the losses caused

19、 by direct human activities in the last 10 years,and 50 per cent of the previously recoverable losses that occurred over the past 25 years.State of Blue Carbon Ecosystems for Climate Action in Asia and the PacificIVThe notional target can also contribute to advancing existing regional and global res

20、toration targets,2 and could potentially store an estimated 209 Mt of CO2.Furthermore,securing the protection of another 40 per cent of existing mangroves in the Asia-Pacific region could increase the value of commercial fish production by an estimated$143-183 billion annually.Indonesia has the larg

21、est potential restoration area in the world.This notional target for the region is broken down to notional targets for each country,as a basis for further assessment and stakeholder dialogue within each country.The proposed target should be considered as a threshold for mangrove restoration;it may b

22、e far below a given countrys ambitions or may exceed current provisions and plans for protection and restoration.The reference to the proportion of“restorable”mangrove cover contributes to the discussion already underway in many countries.Coral reefs TheAsia-Pacificregionalonesupportedover77percento

23、ftheworldscoralreefsin2019.The annual value of these ecosystem services is assessed at an astounding$7.1 trillion.Coral reefs cover less than 0.2 per cent of the global ocean floor,but they are one of the most diverse ecosystems on Earth,providing habitat for about 25 per cent of all known marine sp

24、ecies.The Asia-Pacific region plays a pivotal role in hosting and preserving most of the worlds coral reefs,contributing substantially to the immense value of these ecosystems in terms of the ecological,economic and social support they provide.Coralreefshavefacedasignificantdecline,withalossofnearly

25、one-quarteroftheircoverinthelast15 years.The rate of coral loss accelerated from 3.4 per cent annually,in the late 2000s to early 2010s,to a staggering 18.7 per cent annually in the early 2010s to late 2010s.Global warming and ocean water acidification pose severe threats to these ecosystems and the

26、ir ability to store carbon,particularly due to the rise in sea surface temperature(SST),which is the primary driver of widespread coral bleaching.More than half of the worlds coral reefs have already vanished,and the projected loss could reach 70-90 per cent if global temperatures increase by 1.5C.T

27、heassessmentofthecarbonbalanceofcoralreefsisdifficult,asoceanacidificationslowstherateofaccumulation of carbon.However,coral reefs are understood as net carbon sinks that provide important protective and biodiversity-related ecosystem services.Amongthevariouschallengesfacedbycoralreefsduetoclimatech

28、ange,theincreasedfrequencyandseverity of coral bleaching are major concerns.Some 70 per cent of Asia-Pacific reefs are likely to experience two bleaching events per decade,and at least half would face annual bleaching events by 2050,based on the Representative Concentration Pathway(RCP)4.5 emissions

29、 scenario.Produced prior to the release of Shared Socioeconomic Pathways(SSPs)defined in the IPCC Sixth Assessment Report on climate change in 2021,the analysis indicates heavier losses under the RCP 8.5 scenarios for bleaching,with up to 93 per cent of Asia-Pacific reefs at risk.This highlights the

30、 urgency of addressing anthropogenic stressors and supporting coral recovery.2.For more information,see“Regional Strategy and Action Plan for Forest and Landscape Restoration in Asia-Pacific”(Bangkok,Food and Agricultural Organization of the United Nations,2018).Available at https:/www.fao.org/docum

31、ents/card/en?details=I8382EN%2f;International Union for Conservation of Nature(IUCN),“The Bonn Challenge”,2020.Available at https:/www.bonnchallenge;United Nations Decade on Ecosystem Restoration 2021-2030,United Nations Environment Programme(UNEP),and Food and Agricultural Organization of the Unite

32、d Nations,“Preventing,halting and reversing loss of nature”,n.d.Available at https:/www.decadeonrestoration.org;and Convention on Biological Diversity,“The Biodiversity Plan:Life on Earth”,n.d.Available at https:/www.cbd.int/gbf/targets/3.C-CO2 Conversion Factor is 3.67(IPCC,2007).State of Blue Carb

33、on Ecosystems for Climate Action in Asia and the PacificVTheAsia-Pacificregionisanticipatedtofacesignificantthreatstoitscoralreefs,with60percentofthemprojected to be at high(34 per cent),very high(17 per cent),and critical(9 per cent)risk from combined local and global pressures by 2030.Urgent recov

34、ery plans are essential,particularly for the critically and very highly threatened coral reefs in the region.Conserving and restoring these high-risk coral reefs could ensure ecosystem services worth$4.05 trillion from 11.5 million hectares of coral reefs by 2030,and$5.14 trillion from 14.6 million

35、hectares by 2050.South-East Asia boasts the most diverse coral reefs globally,yet they are also the most jeopardized,with over95percentfacingthreatsduetoglobalwarmingandoceanacidification.Indonesia holds the largest expanse of threatened coral reefs,primarily driven by fishing pressures.More than 65

36、 per cent of coral reefs in the Indian Ocean are under stress due to local threats,while nearly 50 per cent of coral reefs in the Pacific region are similarly threatened.This adversity has far-reaching consequences,which negatively impact coastal communities and the food security of the area.To safe

37、guard the resilience and well-being of coral reef ecosystems,it is imperative to maintain ongoing monitoring efforts aimed at mitigating local human-induced pressures,land-based and marine pollution,overfishing,and destructive fishing practices,while simultaneously addressing global climate change,i

38、ncluding ocean acidification.SeagrassesTheAsia-Pacificregionishometoroughlyaquarteroftheworldsseagrassmeadows.These ecosystems,despite covering a small fraction of the ocean floor,store a remarkable 18 per cent of the worlds oceanic carbon.They are exceptionally efficient at carbon storage;up to 40

39、times more so than land-based forests.These seagrass meadows also serve as a natural buffer against coastal erosion caused by storms.SeveralstudieshavedocumentedsignificantlossesofseagrassinOceaniaandSouth-EastAsia.The rate of decline is over 20 per cent in some areas,such as Viet Nam and the Philip

40、pines.Over 60 per cent of tropical seagrass beds in South-East Asia experienced a decline over the past two decades with an average annual reduction of 10.9 per cent,while 20 per cent of the beds expanded at an average annual rate of 8.1 per cent.The driving forces behind these changes were diverse,

41、and included various human-induced threats,such as coastal development,fisheries,and aquaculture,as well as extreme climate events.Despite hosting incredibly diverse seagrass ecosystems,this region is relatively underexplored.Seagrass beds offer significant carbon storage benefits and can release su

42、bstantial carbon whendisturbed.In the Asia-Pacific region seagrass meadows span approximately 14.92 million hectares.They are estimated to store a remarkable 2.088 Gt carbon and provide ecosystem services valued at approximately$432 billion annually.However,approximately 0.15 petagram(Pg)of carbon i

43、s emitted annually from disturbed seagrass ecosystems globally,equivalent to 3 per cent of the annual global carbon emissions from deforestation.In Asia and the Pacific,emissions from disturbed seagrass ecosystems makes up about half of the global figure.Encouraging carbon markets for seagrass prese

44、rvation is critical.The diverse services these ecosystems offer make them integral to climate change mitigation and adaptation.This assessment conducts a deep-dive into the condition of mangroves,coral reefs and seagrass in four Asia-Pacific countries,namely Bangladesh,Indonesia,Maldives and Samoa.T

45、he restoration of mangroves could sequester an estimated 2.09 MtCO2 in Bangladesh,153 MtCO2 in Indonesia,and 0.01 MtCO2 in Samoa annually,in the long run.Additionally,these restored ecosystems could offer valuable services estimated at$39,647 million in Indonesia,$1,148.6 million in Bangladesh,and$3

46、.2 million in Samoa,annually.Investments aimed at preserving threatened coral reefs by 2030 could yield significant annual ecosystem services with values estimated at around$900 million in Indonesia,$41.53 million in Maldives,and$11.86 million in Samoa.Furthermore,addressing potential losses and deg

47、radation in seagrass areas could help to prevent emissions of approximately 224 MtCO2 in Indonesia,40 MtCO2 in Maldives,and 3.6 MtCO2 in Samoa by 2030.State of Blue Carbon Ecosystems for Climate Action in Asia and the PacificVIIt is crucial to emphasize the lack of existing literature and assessment

48、s concerning the ever-changing nature of blue carbon ecosystems in the Asia and Pacific region.This knowledge deficit underscores a significant gap in our understanding of nature-based solutions and the untapped potential for investments related to the pivotal role of these blue carbon ecosystems in

49、 the intricate dynamics of carbon sequestration and release within the region.Addressing these gaps is imperative for harnessing the full ecological and climate-regulating potential of these invaluable ecosystems.Key recommendations This report recommends national efforts to assess,re-assess or set

50、targets for restoration of blue carbon ecosystems.The notional targets for mangrove restoration proposed in this report for 24 Asia-Pacific countries and territories can provide input to these efforts,and support integration of blue carbon into the second cycle of NDC updates(NDC 3.0)(ESCAP and othe

51、rs,2023).The report also underlines the need for strengthened regional action for:Investment in protection of all blue carbon ecosystems.Ecosystem assessment,in particular,for seagrasses,where gaps in knowledge are significant.Development of national and local enabling environments to increase inves

52、tments in the restoration and preservation of mangroves,coral reefs,and seagrasses to leverage their full potential for carbon sequestration and climate adaptation.Enhancing the capacity of policymakers to integrate blue carbon into the second cycle of NDC updates(NDC 3.0)through engagement with loc

53、al governments and communities.Establishing regional networks of blue carbon experts to support research,monitoring,target setting,planning and integrating blue carbon into NDCs.The complexity of the challenges faced,the degree of threat,and the importance of blue carbon ecosystems for both mitigati

54、on and adaptation emphasizes the need to fully empower local communities,indigenous peoples,and local governments as co-investors in conservation and restoration efforts.State of Blue Carbon Ecosystems for Climate Action in Asia and the PacificVIITable of ContentsExecutive Summary IIITable of Conten

55、ts VIIList of Figures VIIIList of Tables VIIIAbbreviations IXAcknowledgements XIntroduction 11Chapter 1:State of key coastal ecosystems in Asia and the Pacific 141.1.Mangrove forests 151.2.Coral reefs 221.3.Seagrasses 29Chapter 2:Action and potential for nature-based climate solutions in Asia and th

56、e Pacific 332.1.Proposing notional targets for conservation and restoration of mangroves 342.2.Conservation and restoration of coral reefs 382.3.Conservation and restoration of seagrasses 40Chapter 3:Conclusion and recommendations 433.1.Conclusion 443.2.Recommendations 45State of Blue Carbon Ecosyst

57、ems for Climate Action in Asia and the PacificVIIIList of FiguresList of TablesFigure 1.Spatial distribution of mangrove forests,coral reefs and seagrasses in the Asia-Pacific region 13Figure 2.Countries with highest gains and losses of mangrove forest cover areain the Asia-Pacific region(ha,2010202

58、0)17Figure 3.Composition of the relative importance of regional drivers of mangrove lossesin the Asia-Pacific region 20Figure 4.Categorization of the coral reefs at risk from the integrated local andglobal threats in the Asia-Pacific region 25Figure 5.Distribution of categories of coral reefs at ris

59、k by 2030 for the Asia-Pacific region 26Figure 6.Occurrence of severe bleaching conditions in a decade in the Asia-Pacific region 27Figure 7.Distribution of seagrass with associated impact from the Combined Human Impact(CHI)in the Asia-Pacific region 31Figure 8.Seagrass species(proportion of 72 spec

60、ies)affected by the major threat categorydue the direct human impacts 32Figure 9.Target increase(per cent)in mangroves area by 2030 37Figure 10.Categorization of the Combined Human Impact on seagrassesin the Asia-Pacific region countries including Indonesia,Bangladesh,Maldives,and Samoa 41Table 1.Ch

61、ange in extent of mangrove forest cover over the last four decades,19802020 16Table 2.Changes in mangrove cover,countries in Asia and the Pacific,1996 to 2020 18Table 3.Regional distribution of mangrove cover;species richness and likelyimpacts of climate change factors by 2100 19Table 4.Coral reef a

62、reas and changes GCRMN subregions,2005-09 to 2015-19 23Table 5.Temporal trends and changes(percentage rate of change)for seagrass bedsin the South-East Asia 30Table 6.Restoration potential of lost mangrove areas 36 State of Blue Carbon Ecosystems for Climate Action in Asia and the PacificIXAbbreviat

63、ionsADBCO2CO2eESCAPFAOGCRMNGMWGNIGTGtCO2ehaICRIIPBESIPCCIUCNkmkm2MEAMgmmMtMtCO2eNbSNDCsNGOOECMSPgSDGSETgUNEPUNEP-WCMCUNICEFUNDPUNFCCCWRIyrAsian Development Bankcarbon dioxidecarbon dioxide equivalentUnited Nations Economic and Social Commission for Asia and the PacificFood and Agriculture Organizati

64、on of the United NationsGlobal Coral Reef Monitoring NetworkGlobal Mangrove Watchgross national incomegigatongigatons of carbon dioxide equivalenthectare International Coral Reef InitiativeIntergovernmental Science-Policy Platform on Biodiversity and Ecosystem ServicesIntergovernmental Panel on Clim

65、ate ChangeInternational Union for Conservation of Naturekilometresquare kilometreMillennium Ecosystem Assessmentmegagram(1 ton)millimetremegatons or million tonsmegatons of carbon dioxide equivalentnature-based solutionsNationally Determined Contributionsnon-governmental organizationother effective

66、area-based conservation measurespetagramSustainable Development GoalsStandard ErrorterragramUnited Nations Environment ProgrammeUnited Nations Environment Programme and World Conservation Monitoring CentreUnited Nations International Childrens Emergency FundUnited Nations Development ProgrammeUnited

67、 Nations Framework Convention on Climate ChangeWorld Resources Institute yearState of Blue Carbon Ecosystems for Climate Action in Asia and the PacificXAcknowledgementsThis report is a synthesis of a technical background paper commissioned by the United Nations Economic and Social Commission for Asi

68、a and the Pacific(ESCAP)under the project Enhancing investments for equitable and accelerated climate action in the post-COVID-19 recovery.The technical background paper written by Sawaid Abbas,Regional Assessment of the Status of Ecosystems as Nature-Based Solutions for Climate Action:Underscoring

69、the role of blue carbon ecosystems in Asia and the Pacific(Abbas,2023),and its synthesis prepared by Akampumuza Precious,were developed under the overall direction of Hitomi Rankine,Aneta Nikolova and Anshuman Varma,with substantive inputs from Sangmin Nam,Director of the Environment and Development

70、 Division of ESCAP.The reviews of the technical background paper provided by Alexey Kravchenko(ESCAP)and participants of the project inception meeting convened on 15 November 2023 in Johor,Malaysia,as an Affiliated Event of the Asia-Pacific Climate Week 2023,are acknowledged with appreciation.Anoush

71、ka Ali edited,proofread,and finalized the publication.Final design,layout,artwork and refined graphs were developed by Jeffrey Williams.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific11IntroductionPreventing perilous climate change by maintaining global warming at or below

72、 1.5C requires undertaking substantial efforts to both remove significant amounts of carbon dioxide from the atmosphere and reduce its emissions.According to the recommendations from the Intergovernmental Panel on Climate Change(IPCC),approximately 730 billion tons of CO2(199 billion tons of carbon)

73、,must be removed from the atmosphere by the end of 2100(IPCC,2018).The carbon sequestration functions of land-based ecosystems reached around 30 per cent of the carbon emissions generated through human activity in the last decade and could provide 20 to 30 per cent of the mitigation required to ensu

74、re that global warming stays below 1.5C towards 2050(IPCC,2022).Biodiversity,which is the variety of life on Earth,is the foundation for human,environmental and socioeconomic well-being.Forest ecosystems are widely known as carbon sinks which play a significant role in the global carbon cycle.Howeve

75、r,ocean habitats like mangroves,coral reefs and seagrasses,if well preserved,could sequester carbon at a rate four times higher than terrestrial forests(UNEP,2024).Mangroves,coral reefs and seagrass meadows are all coastal ecosystems which are powerful allies against climate change as they provide i

76、nvaluable natural services,including sequestering carbon dioxide,boosting biodiversity,protecting coasts from rising sea levels and sea surges,supporting local livelihoods,and are drivers of national economies.This assessment focuses on trends in the status of carbon sequestration of mangroves,coral

77、 reefs and seagrasses,to devise effective and informed policies to preserve these resources and combat the adverse effects of climate change.Regional mitigation challengesFollowing the IPCC Sixth Assessment Reports recommendations(IPCC,2023),there has been a call for action to ensure that greenhouse

78、 gas emissions peak by 2025 and that emissions decline by at least 43,60,and 84 per cent against a 2019 baseline by 2030,2035 and 2050,respectively.This translates to a reduction in greenhouse gas emissions in the Asia-Pacific region equivalent to 17.02 GtCO2e by 2030,11.94 GtCO2e by 2035,and 4.78 G

79、tCO2e by 2050 from 2019 levels(ESCAP and others,2023).However,based on the existing commitments in the NDCs of member States in the Asia-Pacific region,both conditional and unconditional,and assuming full implementation,it is projected that greenhouse gas emissions will still be relatively high,esti

80、mated at 26.73 GtCO2e by 2030(ESCAP and others,2023).The Asia-Pacific region accounts for more than half of global energy consumption,with 85 per cent of regional consumption coming from fossil fuels.Regional climate threats and nature-based solutionsThe IPCC has warned that the global mean surface

81、temperature by 2100 is likely to increase by 1.4C to 4.4C under five different greenhouse gas emissions scenarios.The Asia-Pacific region is highly vulnerable to climate change.The region has a diverse geography,with extensive coastlines,many small island countries,and low-lying coastal territories.

82、This makes it susceptible to rising sea levels and extreme weather events.Half of Asias population(2.4 billion people)live in low-lying coastal areas that will be at risk from sea level rise,increased storms,and flooding,with coastal ecosystems also at significant risk.The direct drivers of change i

83、n ecosystem services include ecosystem degradation,species introduction or removal,pollution and changes in freshwater systems,climate change,and other natural drivers(e.g.,volcanos,evolution,etc).The indirect drivers of changes include demographic,economic,sociopolitical,science and technology,and

84、cultural and religious factors.(Duescu,2019).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific12This report covers mangrove,seagrass and coral ecosystems.These and other vegetated coastal ecosystems serve as the foundation for coastal fisheries(Saintilan and others,2023).The

85、y play a crucial role in supporting 95 per cent of commercially valuable fish worldwide by serving as essential nursery habitats for juvenile fish(Jnes and others,2020).These“blue carbon ecosystems”are also well placed to contribute to maintaining warming below 2C by sequestering carbon in the range

86、 of 300 to 900 million metric tons of CO2e annually(Murray and others,2011).This accounts for 7-20 per cent of the yearly emissions resulting from global deforestation and forest degradation(Van der Werf and others,2009),even though the blue carbon ecosystems only cover an area equivalent to 1-2 per

87、 cent of the total forested area(Murray and others,2011;FAO,2011).Mangroves stand out as one of the most carbon-rich forms of vegetation(Donato and others,2011).Regional actions and blue carbonThere is a strong demand for nature-based solutions in the Asia-Pacific region.Over 30 per cent(85 million

88、tons of nature-based credits)of all nature-based credits issued globally have come from the Asia-Pacific region.Overall,the investment in nature-based solutions in the Asia-Pacific region is limited and focused on terrestrial ecosystems like forests(Carbon Market Institute,2021).Nature-based carbon

89、sequestration projects are still in their early stages of development in this region,but there is significant potential for growth(Carbon Market Institute,2021;UNEP,2022).Most projects have been concentrated in a few countries,and most of these projects have involved forestry and revegetation.Howeve

90、r,there is also significant untapped potential for nature-based carbon sequestration projects in many other countries in the region,particularly in island countries.The wide coverage of blue carbon ecosystems in the Asia-Pacific region provides an opportunity for member States to leverage nature-bas

91、ed solutions for climate action and ecosystem services(Figure 1).The expansion of initiatives such as mitigation banking,and the development of methodologies for blue carbon,could attract the interest of private sector actors(Carbon Market Institute,2021;Climate Focus,2011;Gordon and others,2011).Am

92、ongst the coastal ecosystems;mangroves,coral reefs and seagrass,the role of mangroves in nature-based solutions is widely acknowledged across countries.Indonesia,Malaysia,and the Philippines are among the few which have explicitly included blue carbon terminology in their policies and established na

93、tional agencies for blue carbon strategies.There is increasing attention paid to the role of seagrasses in carbon sequestration.Coral reefs,while acknowledged as contributing to carbon sequestration,are generally considered“non-actionable”in climate policy.However,the important role played by coral

94、reefs in maintaining the health of other blue carbon ecosystems and marine life,points to the need for investment in their conservation.Four countries,namely Bangladesh,Indonesia,Maldives and Samoa,receive particular attention in this report in light of the activities of the project,“Enhancing inves

95、tments for equitable and accelerated climate action in the post-COVID-19 recovery”,under which this report is issued.National strategies for integrating blue carbon into NDCs and climate policies vary across these countries.Bangladesh,for instance,though not using the term blue carbon in its NDC,rec

96、ognizes the role of mangroves in climate action through the Bangladesh Climate Change Strategy and Action Plan.The country has already raised substantial mangrove plantations contributing to carbon sequestration and has declared various coastal protected areas.Meanwhile,Indonesia has been developing

97、 a Blue Carbon Strategy Framework under its National Medium-Term Development Plan for 2020-2024,with multiple agencies overseeing its implementation.They are guided by presidential decrees and regulations focusing on ocean and marine resource conservation,involving government bodies,civil society or

98、ganizations and the private sector,aiming to restore 1.82 million hectares of mangrove ecosystems by 2045.In Samoa,the NDC is under review to consider blue carbon as a carbon sink,and the country has initiated the Mangrove Ecosystems for Climate Change Adaptation and Livelihoods program.Overlooking

99、blue carbon ecosystems may result in the underestimation of greenhouse gas sinks and inaccurate reporting of greenhouse gas emissions at the national level.Challenges in integrating blue carbon into the Nationally Determined Contributions(NDCs)include data limitations,weak technical capacity,coordin

100、ation issues,overlapping mandates,ecosystem degradation and funding constraints.However,opportunities arise as stakeholders grow more aware of the importance of blue carbon at international,national,and subnational levels.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific13Fi

101、gure 1.Spatial distribution of mangrove forests,coral reefs and seagrasses in the Asia-Pacific regionSource:Authors compilations from mangrove cover maps(Bunting et al.,2022),coral reef maps from Ocean Data Viewer(UNEP-WCMC,n.d.),which is based on several data sources including(IMaRS-USF,2005;IMaRS-

102、USF and IRD,2005;Spalding et al.,2001;UNEP-WCMC et al.,2021).and mapped area of seagrass(UNEP-WCMC and Short,2021).Report overview and data sourcesChapter 1 of this assessment provides a comprehensive overview of the status of key regional ecosystems as carbon dioxide sinks and documents the changes

103、 in blue carbon ecosystems in the Asia-Pacific region,particularly focusing on mangroves,coral reefs and seagrass.Chapter 2 identifies actions towards,and the potential for nature-based climate solutions at the regional level.It also proposes notional targets for mangrove restoration to support nati

104、onal planning,based on a closer look at the findings for selected countries,including Bangladesh,Indonesia,Maldives and Samoa under each blue carbon ecosystem.The notional targets are provided to illustrate how they might contribute to national target setting.Chapter 3 provides broad conclusions for

105、 regional action.To assess potential shifts within these ecosystems,this evaluation leverages both global and regional datasets,along with estimates,to map and monitor key indicators.The findings presented in this assessment are derived from a desktop analysis of regional and global assessments rega

106、rding changes in ecosystems,as well as from the spatial overlay analysis of indicators specific to the Asia-Pacific region.These estimates regarding the state and transformations of various ecosystem types are derived from a time series of remote sensing products developed by the United Nations Econ

107、omic and Social Commission for Asia and the Pacific(ESCAP),United Nations Environment Programme(UNEP),the Food and Agriculture Organization of the United Nations(FAO),the United Nations Framework Convention on Climate Change(UNFCCC),the World Resources Institute(WRI),Global Mangrove Watch(GMW),and o

108、ther published scientific and knowledge products.It is important to note that all geographic information,such as scale,resolution,date,and the interpretation of the sources is subject to constraints.Reliance on global datasets poses inherent limitations to accuracy.State of Blue Carbon Ecosystems fo

109、r Climate Action in Asia and the Pacific14STATE OF KEY COASTAL ECOSYSTEMS IN ASIA AND THE PACIFICCHAPTER 1State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific151.1.Mangrove forestsMangroves are the dominant vegetation in the intertidal zone of sheltered(muddy)coastlines found i

110、n tropical,subtropical,and warm temperate oceans.The term mangrove is used to describe both a specific type of vegetation and a distinctive habitat,which is also referred to as tidal forest,swamp,wetland,or mangal(Duke and others,2007;Spalding,2010).A mangrove habitat is characterized by a continuum

111、 of features,including mudflats(zone below mean sea level),mangrove forests(zone between mean sea level and the level of higher neap tides),and salt flats(zone above the level of higher neap tides).The distribution of these features may vary across space and time due to variations in climate,topogra

112、phy,and hydrology(Woodroffe,1992).The global coverage of mangrove forests was estimated to be over approximately 147,359 km2 in 2020,with 51 per cent of those forests(74,808 km2)located in the Asia-Pacific region,presenting an enormous opportunity for carbon sequestration in the region(Bunting and o

113、thers,2022;UNEP,2023).These forests stand out as some of the most carbon-dense ecosystems.Mangroves store an average of around 1,023 metric tons of carbon per hectare annually(Donato and others,2011),equivalent to around 3,750 metric tons of potential CO2 emissions per hectare.3 Estimates of carbon

114、storage rates can vary widely,depending on geographic region,stage of growth,depth of soil taken into account in the methodology and other factors;this estimate takes into account the whole mangrove system,including organic-rich soils extending from 0.5 to over 3 metres in depth for mangrove forests

115、 in the Indo-Pacific region,within defined latitudes(Donato and others,2011).Some 50-90 per cent of the carbon sequestered by mangrove forests is stored underground(van der Werf and others,2009;Donato and others,2011;Leal and Spalding,2022).Their remarkable carbon storage capacity is estimated to be

116、 up to four times greater than that of certain other forested environments,like temperate and boreal forests(Donato and others,2011).Given the substantial carbon reservoir within mangroves,it becomes imperative to protect these existing areas to mitigate potential future CO2 emissions(Leal and Spald

117、ing,2022).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific16Globally,the coverage of mangrove forests decreased by 5,245 km2(3.4 per cent)between 1996 and 2020.With a net loss of 4.3 per cent(3,338 km2)in mangrove coverage between 1996 and 2020,Asia and the Pacific experien

118、ced the highest decline of global regions,accounting for approximately 63 per cent of the global loss(Table 1).Between 2010 and 2020,the loss in mangrove cover ranged between 1,000 and 22,000 hectares for several locations in the Asia-Pacific region(Figure 2,Table 2).The most significant cause of ma

119、ngrove loss is aquaculture development,followed by natural retraction.Other causes include conversion to oil palm and rice cultivation,direct settlement,wood extraction,natural disasters and indirect settlements(FAO,2023).Table 1.Change in extent of mangrove forest cover over the last four decades,1

120、980 2020RegionYearExtent(km2)Annual change(km2)Changefrom 1996(km2)Changefrom 1996(per cent)Asia-Pacific198098,950.00199087,820.00199678,146.35200776,413.79-157.51-1,732.56-2.22200875,596.75-817.05-2,549.61-3.26200975,471.84-124.90-2,674.51-3.42201075,228.34-243.51-2,918.02-3.73201574,811.38-83.39-3

121、,334.97-4.27201674,637.03-174.36-3,509.33-4.49201774,669.2232.20-3,477.13-4.45201874,784.23115.00-3,362.13-4.30201974,813.6929.47-3,332.66-4.26202074,808.56-5.13-3,337.79-4.27Source:Authors compilation from Food and Agriculture Organization of the United Nations(FAO),The worlds mangroves 20002020(Ro

122、me,2023).Note:Due to the recent advancement in technologies,and the increase in the capacity of different countries to map and quantify national forest resources,these maps and area statistics may not be consistent with other global,regional,and national level assessments.Note:The figures for 1980 a

123、nd 1990 are from FAOs assessments which come from different sources and may not be consistent with the figures from 1996 to 2020,which are derived from the consistent estimates of global mangrove forest extents(Bunting and others,2022).GROWING THREATS TO HALF OF THE WORLDS MANGROVES HOSTED IN THE AS

124、IA-PACIFIC REGIONState of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific17Figure 2.Countries with highest gains and losses of mangrove forest cover area in the Asia-Pacific region(ha,20102020)Source:The net change is estimated from the mapped mangrove area in 2010 and 2020(Bunting

125、 and others,2022;Leal and Spalding,2022;UNEP,2023).Note:The mangrove area is aggregated at country level.The net change is estimated from the mapped mangrove area in 2010 and 2020.Thailand (4,823.41)India (1,288.35)Cambodia (638.64)Philippines (3,522.79)Bangladesh (725.04)China(446.48)1234561728Mala

126、ysia (-3,507.43)Myanmar (-4,867.17)Australia (-9,175.68)Papua New Guinea (-4,577.48)Pakistan (-6,790.74)Indonesia (-21,466.44)78910111239410511612State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific18Table 2.Changes in mangrove cover,countries in Asia and the Pacific,1996 to 20

127、20Country199620102020Gain/Loss1996-2020Gain/Loss2010-2020Area(ha)Area(ha)%Area(ha)%Thailand259,819247,975252,799-7,020.00-2.704,823.411.95Philippines292,732281,275284,798-7,934.19-2.713,522.791.25India411,119402,496403,785-7,333.94-1.781,288.350.32Bangladesh444,717447,661448,3863,668.630.82725.040.1

128、6Cambodia64,65662,05362,692-1,963.90-3.04638.641.03China24,49921,13421,581-2,918.52-11.91446.482.11Sri Lanka25,86119,73419,874-5,986.90-23.15140.810.71Fiji48,57248,77248,814241.950.5042.730.09Brunei11,46211,48211,49734.960.5014.660.13Japan1,0361,0191,031-4.87-0.4711.781.16French Polynesia1221201202.

129、982.445.454.55Guam5252520.380.730.380.73Cook Islands3330.000.000.000.00Kiribati1461461460.000.000.000.00Maldives9797970.000.000.000.00Marshall Islands3333330.000.000.000.00Tuvalu9990.000.000.000.00American Samoa333232-0.55-1.68-0.14-0.43Samoa234239232-1.77-0.76-6.50-2.72Palau5,6625,7005,68825.910.46

130、-12.31-0.22Tonga1,0551,0681,043-12.09-1.15-25.39-2.38Singapore840775730-110.66-13.17-44.81-5.79Vanuatu1,6231,6371,584-39.36-2.43-52.85-3.23Micronesia,Federated States of9,0849,0178,794-289.15-3.18-222.25-2.46Solomon Islands52,73152,89852,651-79.95-0.15-247.68-0.47Islamic Republic of Iran14,26911,469

131、11,177-3,092.42-21.67-291.93-2.55New Zealand29,02729,99829,608581.072.00-389.33-1.30Viet Nam196,419188,134187,147-9,272.27-4.72-986.91-0.52Malaysia531,482528,082524,575-6,906.92-1.30-3,507.43-0.66Papua New Guinea457,348457,051452,474-4,873.92-1.07-4,577.48-1.00Myanmar582,120548,406543,539-38,581.14-

132、6.63-4,867.17-0.89Pakistan100,00289,57982,789-17,213.56-17.21-6,790.74-7.58Australia1,065,4721,026,2561,017,081-48,391.26-4.54-9,175.68-0.89Indonesia3,127,3022,974,8652,953,398-173,903.84-5.56-21,466.44-0.72Total Mangroves in ESCAP7,759,6397,469,2687,428,264-331,375-4.27-41,004.52-0.55Source:The net

133、 change is estimated from the mapped mangrove area in 2010 and 2020(Bunting and others,2022;Leal and Spalding,2022;UNEP,2023).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific19As mangrove forests disappear,the region is gradually losing the sequestration potential associate

134、d with mangroves.Globally,by one estimate,mangrove forests store 6.23 gigatons(Gt)of carbon,equivalent to potential emissions of 22.86 gigatons of CO2(UNEP,2023).Between 1996 and 2020,net losses of carbon stored in mangrove forests in the Asia-Pacific region were estimated at 98 Mt(UNEP,2023)or 70 p

135、er cent of the global net loss of 139 Mt(UNEP,2023).The region released an estimated 184 Mt of sequestered carbon due to mangrove forest loss and degradation,with Indonesia experiencing the greatest losses,followed by Australia.On the other hand,gains in mangrove cover in the region sequestered 86 M

136、t of carbon,with the largest net gain in Bangladesh(UNEP,2023).The loss of just 1 per cent of the current global mangrove coverage(1500 km2),or 2 per cent of mangroves in the Asia-Pacific region,could lead to emissions of 230 MtCO2 equivalent equating to over 520 million barrels of oil,or the annual

137、 emissions of 49 million cars.Therefore,it is critical to protect,conserve and prevent the degradation of mangrove ecosystems(Leal and Spalding,2022).The future of mangroves in the Asia-Pacific region will ultimately be shaped by a combination of both climatic and non-climatic direct drivers(Table 3

138、).Climate change is impacting mangroves at regional scales through a variety of interrelated and spatially variable factors,including sea level rise,increased storminess,altered precipitation regime,and increasing temperature(Table 3).The complex interplay of these factors directly affects the produ

139、ctivity of mangrove ecosystems,increases erosion and salinity,alters sediment supply and threatens the drowning of mangroves(Giri and others,2011;IPCC,2014;Ward and others,2016).CONVERSION TO OIL PALM,AQUACULTURE AND RICE CULTIVATION ARE DRIVING MANGROVE LOSS IN SOUTH AND SOUTH-EAST ASIATable 3.Regi

140、onal distribution of mangrove cover;species richness and likely impacts of climate change factors by 2100RegionMangroves area(ha)Percentage of global mangroveNumber of speciesSea level rise(mm/yr)Temperature increasePrecipitation changeTropical cyclone increaseAsia5,776,17341.9552.05.4Very likelyVer

141、y likely(+)LikelyAustraliaNew Zealand1,009,7137.336(1 NZ)2.03.8Very likelyVery likely(+)LikelyPacific623,7554.5351.42.0Very likelyVery likely(+)LikelySource:Regional distribution of mangrove cover in the Asia-Pacific region taken from C.Giri,and others,“Status and distribution of mangrove forests of

142、 the world using earth observation satellite data”,Global Ecology and Biogeography,vol.20,No.1(January 2011).Estimates of cover may vary depending on data sources and analysis.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific20The impact of rising sea levels will be most pro

143、nounced in mangrove areas where the sediment elevation is decreasing and there is limited space for landward migration(Gilman and others,2008).Rising sea levels due to global warming pose the most significant threat to mangroves,impacting their contributions to the well-being of people,especially in

144、 countries like Bangladesh,the Philippines,New Zealand,Viet Nam,and China(IPBES,2019b).The impact of rising sea levels is expected to affect mangroves in all regions,but the specific consequences at the local level are likely to exhibit greater variation(Ward and others,2016).Non-climatic drivers,su

145、ch as human-induced alterations in land use,urbanization,and the expansion of agriculture and aquaculture,will likely be the primary agents of change in mangrove habitats,particularly in the near and short-term future.However,the extent of these changes will vary across different subregions.The incr

146、easing demand for land makes small island mangrove habitats especially vulnerable to future alterations,putting them at risk of local extinction(IPBES,2019b).In South-East Asia,the primary non-climatic drivers of mangrove loss are the expansion of agriculture into existing mangrove habitats,followed

147、 by a rapid increase in brackish water aquaculture(Figure 3).Rice agriculture has been a major driver of mangrove loss in Myanmar(Estoque and others,2018;Richards and Friess,2016;Webb and others,2014;Zckler and Aung,2019).It has been projected that unless a suitable balance is achieved locally,mangr

148、oves in the Ayeyarwady(Irrawaddy)Delta of Myanmar could vanish by 2030 due to the ongoing rate of agricultural expansion(Webb and others,2014).The expansion of oil palm plantations and conversion of mangroves to ponds is anticipated to pose a growing threat to mangrove forests in South-East Asia,esp

149、ecially in Indonesia and Papua New Guinea,leading to mangrove deforestation,habitat loss,and biodiversity decline(Prakoso and others,2023;Richards and Friess,2016).Additionally,the extensive mangrove die-back in the Gulf of Carpentaria,Australia,in late 2016,which affected an area of around 7,000 he

150、ctares,is likely due to an extended drought period(Duke and others,2017).Figure 3.Composition of the relative importance of regional drivers of mangrove losses in the Asia-Pacific regionSource:Authors compilation from Food and Agriculture Organization of the United Nations(FAO),The worlds mangroves

151、20002020(Rome,2023).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific21Over the past two decades,the main drivers of mangrove loss in the Asia-Pacific subregions were aquaculture,accounting for 35 per cent of the loss,natural retraction(17 per cent),conversion for rice culti

152、vation(13 per cent),oil palm(13 per cent),and the remainder(22 per cent)came from other sources,including natural disasters,direct and indirect settlements(Figure 3).Notably,over the last decade,the role of aquaculture,conversion to rice and direct settlements have declined,while the conversion to o

153、il palm plantations emerged as the dominant driver of mangrove loss.A significant increase in loss due to natural disasters and indirect settlements has also been reported in the region(FAO,2023).However,countries like India,Bangladesh and Pakistan have been relatively successful in maintaining a st

154、able mangrove extent(Giri and others,2015).These countries have established an extensive network of protected areas that have played a crucial role in preserving mangroves,despite substantial population pressure in the vicinity(IPBES,2019b).While the rate of mangrove forest loss in the region is ala

155、rming,recent trends show some hope due to a slow-down in net losses.Over the last decade,between 2010 to 2020,the net loss in global mangrove cover declined to 420 km2(0.05 per cent)from 2,918 km2(3.73 per cent)during 1996 2010(Bunting and others,2022;Leal and Spalding,2022;UNEP,2023).In South and S

156、outh-East Asia,the annual rate of net loss in mangrove cover has declined from 0.23 per cent,in 2000-2010,to 0.11 per cent in 2010-2020(FAO,2023).Given that the subregion accounts for almost all of Asias mangroves(99.5 per cent),the slowing losses presents an opportunity for regional reduction in ma

157、ngrove losses.East Asia is the only region where mangrove area has increased in the past 20 years,at a rate of 2.32 per cent per year(FAO,2023).MANGROVES DEFORESTATION IS SLOWING IN THE REGIONYET IS RESPONSIBLE FOR 63 PER CENT OF GLOBAL LOSSState of Blue Carbon Ecosystems for Climate Action in Asia

158、and the Pacific221.2.Coral reefsDespite covering less than 0.2 per cent of the global ocean floor,coral reefs are one of the most diverse ecosystems in the world,and provide a habitat for about 25 per cent of known marine species.Occurring in more than 100 countries and territories,these reefs are h

159、ighly recognized for their significant ecological,economic and social services,which are estimated to be$2.7 trillion per year(Souter and others,2020).The direct contributions of coral reefs to carbon sequestration are influenced by its various biological functions promoting carbon uptake and emissi

160、ons.The carbon balance attributable to the physical structure of the reef is likely to vary.However,these ecological powerhouses play an important role in the global cycling and uptake of carbon by positively influencing the health and functioning of nearby mangroves and seagrass meadows(Great Barri

161、er Reef Foundation,2023).The efficacy of the oceans as a carbon sink is expected to decrease in the future due to a range of factors,including increased outgassing of natural CO2 related to ocean warming,changes in ocean circulation and biology(Gruber and others,2023).Although there is no serious di

162、scussion about carbon financing for coral reefs due to the difficulty of assessing their contributions as carbon sinks,the overall support provided by coral reefs to marine life at all trophic levels of the food chain underlines the importance of coral reefs as blue carbon ecosystems.The Global Cora

163、l Reef Monitoring Network(GCRMN)is a network of scientists and organizations established to monitor the status and trends in coral reef ecosystems.GCRMN is a part of the International Coral Reef Initiative(ICRI)and operates in 10 regional nodes to collect and disseminate information on the health of

164、 coral reefs.Out of these regions,four fall in the Asia-Pacific region,which include South Asia,East Asia,the Pacific,and Australia(Table 4).In 2019,the Asia-Pacific region hosted more than 77 per cent(20 million hectares)of the global area of coral reefs(26 million hectares)(Souter and others,2020)

165、.Coral reefs provide ecosystem services valued,by one often-cited estimate,at$352,249 per hectare per year(Costanza and others,2014).With an approximate extent of 20 million hectares(Souter and others,2020),the annual value of ecosystem services provided by the coral reef ecosystems in the Asia-Paci

166、fic region is estimated at$7.1 trillion.Similarly,the global value of ecosystem services provided by the 26 million hectares of coral reefs could be worth some$9.15 trillion annually.THE ASIA-PACIFIC REGION COMPRISES ONE-FOURTHOF THE GLOBAL CORAL REEFSState of Blue Carbon Ecosystems for Climate Acti

167、on in Asia and the Pacific23The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services(IPBES)(IPBES,2019a),and the Special Report on the Ocean and Cryosphere in a Changing Climate by the Intergovernmental Panel on Climate Change(IPCC,2022)reports provide an alarming insight

168、 on the state of coral reefs.More than 50 per cent of the worlds coral reefs have already disappeared,and the projected loss could reach 70-90 per cent at a warming of 1.5C(Souter and others,2020).Losses from the region make up a significant proportion of global losses.During the last 15 years,the r

169、egion has experienced a decline of 22 per cent of its coral cover.The loss of coral cover accelerated from 3.4 per cent(during the late 2000s to early 2010s)to 18.7 per cent(during the early 2010s to late 2010s).A cumulative loss of 14 per cent(11,700 km2)in the global hard coral cover area was obse

170、rved between 2009 and 2018.The hard coral cover is a measure of the percentage of reef surface covered by live hard coral instead of sponges,algae,or other organisms.It is a globally accepted and universally used indicator of coral reef health.The significant loss of hard coral cover is attributed t

171、o recurring large-scale coral bleaching events.Coinciding with the loss of hard coral reefs,the presence of algae has increased by 20 per cent since 2011.The algal cover is an indicator of stress on coral reefs(Souter and others,2020).Preserving these ecosystems is vital for the welfare of coastal c

172、ommunities,aligns with the Sustainable Development Goals of the 2030 Agenda(Souter and others,2020)and is critical for regional and global food security.THE REGION HAS LOST A QUARTER OF ITS CORAL REEFS N THE LAST 15 YEARS Table 4.Coral reef areas and changes GCRMN subregions,2005-09 to 2015-19Subreg

173、ionsCoral area km2Proportion of global area(percentage)Mean absolute change(percentage)2005-09 2010-142010-14 2015-192005-09 2015-19South Asia10,9494.224.3-12.9-8.7East Asia78,27230.15-2.7-0.2-2.8Australia41,80216.1-4.6-1.7-6.6Pacific69,42426.73-0.4-3.9-4.3Asia-Pacific region200,44777-3.4-18.7-22.4G

174、lobal total259,647Source:Authors compilation from D.Souter,and others,eds,“Status of Coral Reefs of the World:2020”,Global Coral Reef Monitoring Network(GCRMN)and International Coral Reef Initiative(ICRI),2020.Available at https:/doi.org/10.59387/WOTJ9184Note:For details on Global Coral Reef Monitor

175、ing Network(GRMN)regions,refer to Sawaid Abbas,“Regional Assessment of the Status of Ecosystems as Nature-Based Solutions for Climate Action:Underscoring the role of blue carbon ecosystems in Asia and the Pacific”,United Nations ESCAP,Environment and Development Division,Bangkok,December 2023.Note:T

176、he Islamic Republic of Iran is part of the ESCAP region.However,it is categorized in the Regional Organization for the Protection of the Marine Environment(ROPME)subregion of the GCRMN.Therefore,the Islamic Republic of Iran is not included in the statistics for the ESCAP region.The whole ROPME subre

177、gions occupy a tiny proportion(less than 1 per cent,2009 km2)of the global reefs.Note:The East Asia subregion in this table includes South-East Asia.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific24The increasing correlation between rising anomalies and sea surface tempera

178、ture(SST)provides strong evidence that rising SST and marine heatwaves are the main causes of large-scale coral bleaching.The cascading impacts of rising SST,and pervasive algal dominance within reef ecosystems make the habitat that is essential for marine biodiversity unfavourable,and undermine the

179、 ability of reefs to provide essential services.Reefs are highly sensitive ecosystems that are greatly threatened by climate change,ocean acidification,land-based pollution,marine pollution,overfishing and destructive fishing practices(IPBES,2019a)and heavy damage to entire reefs in the region(Bellw

180、ood and others,2004).Furthermore,sea level rise(SLR)can cause coral reefs to lose elevation leading to increased inundation and wave exposure,which can damage the reef.Despite vertical adjustment-the ability to grow vertically to keep up with sea level rise(Cahoon and others,2019;IPCC,2022),if the r

181、ate of SLR exceeds the rate of reef growth,the reef can be submerged and lost.Hence,the areal extent of the reefs can expand or contract depending on the rate of loss and the rate of new habitat formation(Saintilan and others,2023).One-third of reef-forming corals in the region are threatened(Huang

182、and Roy,2015),leading to the collapse of important coastal ecosystems and undermining resilience.Both local and global factors pose multiple threats to coral reef ecosystems.Over 60 per cent of reefs are threatened by local sources,and 75 per cent are threatened when combined with climate change.Fig

183、ure 4 shows the distribution of categories(varying degrees of risk)of coral reefs at risk from the integrated local and global threats projected for 2030 in the Asia-Pacific region(Burke and others,2011).For most parts of the Asia-Pacific region,the projected risk level ranges between“high”and“criti

184、cal”(Figure 5).The compound impact of climate change also increases the severity of degradation(Burke,Reytar,and Spalding,2012).It is estimated that up to 90 per cent of corals in South and South-East Asia will suffer severe degradation by 2050,even under conservative climate change scenarios(IPBES,

185、2019b).South-East Asia has the most diverse coral reefs on Earth,but they are also the most threatened;half of these are at high risk,primarily from coastal development and fishing-related activities(Bryant and others,1998).Indonesia has the largest area of threatened coral reefs,with fishing threat

186、s being the main stressor(Bruno and Selig,2007).Over 65 per cent of the coral reefs in the Indian Ocean are under stress due to local threats.The Maldives,the Chagos Archipelago,and the Seychelles are home to some of the most pristine coral reefs in the Indian Ocean.While these reefs are currently u

187、nder relatively low threat,overfishing,land-based pollution and coastal development are all potential threats to their long-term health(Burke and others,2011).In the Pacific islands,nearly 50 per cent of coral reefs are threatened,and approximately 14 per cent of Australias coral reefs are threatene

188、d,though the Pacific is ranked as the least threatened coral reef region(IPBES,2019b).CORAL REEFS ARE INCREASINGLY THREATENED BY GLOBALAND LOCAL FACTORSState of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific25Figure 4.Categorization of the coral reefs at risk from the integrated l

189、ocal and global threats in the Asia-Pacific regionSource:L.Burke,and others,“Reefs at Risk Revisited”,Washington,D.C.:World Resources Institute(WRI),2011.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific26Figure 5.Distribution of categories of coral reefs at risk by 2030 for

190、 the Asia-Pacific region Source:Authors compilation from L.Burke,and others,“Reefs at Risk Revisited”,Washington,D.C.:World Resources Institute(WRI),2011.Available at https:/www.wri.org/research/reefs-risk-revisitedNote:The analysis is based on the quantification and mapping of threats to the worlds

191、 coral reefs incorporating more than 50 datasets related to human pressure in coral reefs.Local threats addressed in this analysis included coastal development,watershed-based pollution,marine-based pollution,damage,overfishing,and destructive fishing.Global threats cover thermal stress(warming sea

192、temperatures,which can induce coral bleaching),and ocean acidification(driven by increased CO2,which can reduce coral growth rates).For more information,refer to Burke and others,2011.A closer look at the climate-related risk paints an even more alarming picture.Of the various threats that coral ree

193、fs face as the climate changes,an increasing frequency and severity of coral bleaching is a major concern.By 2050,under the emission scenario RCP 4.5,70 per cent of the coral reefs in the Asia-Pacific region are projected to bleach twice in a decade(2X),and at least half of these could experience an

194、nual bleaching(10X)(Figure 6).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific27Figure 6.Occurrence of severe bleaching conditions in a decade in the Asia-Pacific region Source:Authors compilation from R,van Hooidonk,J.A Maynard,and S.Planes,“Temporary refugia for coral ree

195、fs in a warming world”,Nature Climate Change,vol.3(February 2013).Available at https:/doi.org/10.1038/nclimate1829;and R.van Hooidonk,and others,“Downscaled projections of Caribbean coral bleaching that can inform conservation planning”,Global Change Biology,vol.21,No.9(September 2015).Available at

196、https:/doi.org/10.1111/gcb.12901;and Coral Reef Watch,“Downscaled climate model projections of coral bleaching conditions”,NOAA Satellite and Information Service,2016.Available at https:/coralreefwatch.noaa.gov/climate/projections/downscaled_bleaching_4km/Note:The Representative Concentration Pathwa

197、ys(RCP)depict potential future scenarios for greenhouse gas and aerosol emissions.According to the IPCC,RCP 4.5 is characterized as a moderate scenario where emissions reach their peak around 2040 and subsequently decrease.On the other hand,RCP 8.5 represents the highest baseline emissions scenario,

198、with emissions persistently increasing throughout the twenty-first century.Produced prior to the release of Shared Socioeconomic Pathways(SSPs)defined in the IPCC Sixth Assessment Report on climate change in 2021,the analysis indicates heavier losses under the RCP 8.5 scenarios for bleaching,with up

199、 to 93 per cent of Asia-Pacific reefs at risk by 2050.This highlights the urgency of addressing anthropogenic stressors and supporting coral recovery.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific28State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific

200、291.3.SeagrassesSeagrass,a beautiful marine flowering plant,is widely distributed along temperate and tropical coastlines of the world.There are more than 70 species of seagrass around the world,found in 159 countries across 6 continents,potentially covering over 30 million hectares,with more than 1

201、 billion people living within 100 km of a seagrass meadow(UNEP,2020).It is one of the most powerful coastal ecosystems that plays a significant role in fishery production(Herrera and others,2022),providing a nursery area to nearby salt marshes,shellfish beds,coral reefs and mangrove forests,habitats

202、 sediment stabilization,water purification,broader ocean functionalities,helping to fight climate change,and protecting coastal communities(Duarte and others,2008;McKenzie and others,2020,2021;Spalding and others,2003;UNEP,2020).Seagrass meadows are pivotal in climate change mitigation through natur

203、e-based solutions.Although they occupy a small portion of the ocean floor,seagrasses play a significant role in carbon storage,accounting for up to 18 per cent of the worlds oceanic carbon.These underwater plants efficiently absorb carbon dioxide from the atmosphere and sequester it in the ocean.The

204、 Asia-Pacific region hosts vast seagrass areas spanning approximately 14.92 million hectares,which is a quarter of the worlds seagrass,and comprises of the worlds most diverse seagrass ecosystems.These meadows collectively store an impressive 2.088 gigatons of carbon,and provide ecosystem services v

205、alued at approximately$432 billion annually.THE ASIA-PACIFIC REGION IS A POWERHOUSE FOR SEAGRASS CARBON SEQUESTRATION State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific30An analysis of temporal variations in seagrass bed area across 68 sites in 9 different countries/territori

206、es in the region revealed some concerning trends(Table 5).More than 60 per cent of these seagrass beds experienced a decline,with an average annual rate of 10.9 per cent.Conversely,20 per cent of the beds saw an increase in size,with an average annual growth rate of 8.1 per cent.This resulted in an

207、overall average decline of 4.7 per cent per year(Sudo and others,2021).The rate of decline is particularly high in Oceania and South-East Asia,where some areas have experienced a decline of over 20 per cent,such as in Viet Nam and the Philippines.Figure 7 shows the extent to which seagrass ecosystem

208、s are exposed to both direct and indirect human influences.The influences are grouped into four distinct risk categories,each reflecting a different level of vulnerability:Critical(greater than 4),Very High(ranging from 3 to 4),High(ranging from 2 to 3),Medium(ranging from 1 to 2),and Low(less than

209、1).In the Asia-Pacific region,most seagrasses are quite vulnerable,including 18 per cent classified as facing“high”risk,9 per cent as“very high,”and 2 per cent as“critical”.ANTHROPOGENIC AND CLIMATE CHANGE PRESSURESARE CAUSING DECLINE OF SEAGRASS BEDSTable 5.Temporal trends and changes(percentage ra

210、te of change)for seagrass beds in South-East AsiaCategoryRecorded samplesRate of changeNumber of samplesRelative proportion(percentage)Annual average,2000-2020(percentage)SEDeclining4464.7-10.92.6Increasing1420.68.12.2Stable1014.700.1Overall68100-4.72Source:Authors compilation from K.Sudo and others

211、,“Distribution,Temporal Change,and Conservation Status of Tropical Seagrass Beds in Southeast Asia:20002020”,Frontiers in Marine Science,vol.8(July 2021).Available at https:/doi.org/10.3389/fmars.2021.637722Note:SE=Standard Error.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pac

212、ific31Figure 7.Distribution of seagrass with associated impact from the Combined Human Impact(CHI)in the Asia-Pacific region Source:Authors compilation.CHI information found in B.S.Halpern,and others,“A Global Map of Human Impact on Marine Ecosystems”,Science,vol.319,No.5865(February 2008).Available

213、 at https:/doi.org/10.1126/science.1149345;and B.S.Halpern,and others,“Recent pace of change in human impact on the worlds ocean”,Scientific Reports,vol.9(August 2019).Available at https:/doi.org/10.1038/s41598-019-47201-9.Seagrass information found in United Nations Environment Programme(UNEP),UN E

214、nvironment World Conservation Monitoring Centre(UNEP-WCMC),and F.Short,“Global distribution of seagrasses(version 7.1).Seventh update to the data layer used in Green and Short(2003).Cambridge,2021.Available at https:/doi.org/10.34892/x6r3-d211.PROTECTION OF SEAGRASS CARBON SEQUESTRATION AND ECOSYSTE

215、MS SERVICES IS VITALIt is imperative to protect seagrass ecosystems to avert carbon release.Seagrass beds,while offering substantial carbon storage benefits,can also release significant carbon when disturbed.Approximately 0.72 Pg of carbon are emitted annually from the Asia-Pacific regions seagrass

216、ecosystems(at a rate of 326 Mg per hectare).This emission may be equivalent to 1.5 per cent of the annual global carbon emissions from deforestation(Pendleton and others,2012;Serrano and others,2021).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific32Figure 8.Seagrass specie

217、s(proportion of 72 species)affected by the major threat category due to direct human impacts Source:F.T.Short,and others,“Extinction risk assessment of the worlds seagrass species”,Biological Conservation,vol.144,No.7(July 2011).Available at https:/doi.org/10.1016/j.biocon.2011.04.010Depletion of th

218、e seagrass ecosystem releases enormous quantities of carbon into the atmosphere.In one incident,in Shark Bay,Australia,one of the worlds largest seagrass ecosystems suffered damage during a marine heatwave in 2010/2011.This event led to the release of an estimated 29 million tons of carbon,and contr

219、ibuted to the decline of species associated with seagrass ecosystems,many of which were of high conservation importance or were commercially targeted(UNEP,2020).The preservation of seagrass ecosystems is vital,and the wide establishment of carbon credits for their protection is imperative,considerin

220、g the diverse services these ecosystems provide.Seagrasses face various threats,including water pollution,climate change,coastal development,overfishing,boat-related damage,diseases,invasive species,ocean acidification,sea level rise,and habitat destruction(UNEP,2020)and the complex interplay of env

221、ironmental and anthropogenic factors(Sudo and others,2021).The biggest threat to seagrass across the world currently is coastal development(Figure 8)(Short and Wyllie-Echeverria,1996).The interaction of human activity with climate-induced changes increases the intensity of damage.For example,increas

222、ing precipitation leads to more runoff of nutrients and silt from land,and runoff and sedimentation is increased by changes in land use,such as deforestation and agriculture(Duarte and others,2008).The combination of these factors is a major threat to the distribution and health of seagrass beds.How

223、ever,there is currently little quantitative understanding of these interactions to plan appropriate management plans(Griffiths and others,2020).The primary cause of seagrass loss is reduced water clarity due to increasing nutrient loading and turbidity,which is linked to fertilizer runoff from agric

224、ulture,sewage discharge,industrial waste,and coastal development(Short and Wyllie-Echeverria,1996).In South-East Asia,increased sediment flow from deforestation in the watersheds is the primary cause of seagrass losses(FAO,2020).Other direct human impacts of the threat to seagrass habitat include fi

225、shing and aquaculture,introduction of exotic species,boating and anchoring,and development-related changes in coastal habitats(UNEP,2020).State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific33ACTION AND POTENTIAL FORNATURE-BASED CLIMATE SOLUTIONS IN ASIA AND THE PACIFICCHAPTER

226、2State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific34The Asia-Pacific region has the highest mangrove restoration potential,as the region with the highest losses.Restoration entails addressing both biophysical aspects,such as water quality and sediment availability,and social

227、 aspects,including land tenure and resource access,to ensure successful restoration outcomes(FAO,2023).The Global Mangrove Alliance(Leal and Spalding,2022)has set a revised goal for 2030,which focuses on securing the future of mangroves and the communities reliant on them.This goal can be summarized

228、 in six words:Prevent Loss(eliminate mangrove loss from direct human activities);Restore Half(re-establish mangroves to cover at least half of recent losses);and Double Protection(increase long-term safeguarding of remaining mangroves by another 40 per cent).Based on this goal,the notional targets f

229、or restoring mangroves coverage in the ESCAP region have been calculated by adding the potential reduction in expected losses by 2030,and the recoverable losses from the lost mangroves area during 1996 to 2020.Targets for the restoration of mangroves play an important role in various national policy

230、 processes,including landscape restoration,biodiversity conservation,disaster risk reduction and climate adaptation and mitigation.Targets set in any of these policy processes should be scientifically grounded as well as socially acceptable.The update of nationally determined contributions targets i

231、s an important opportunity for re-assessing restoration targets where they exist,and for putting in place policy processes to set new targets,where they do not exist,or may be outdated.This chapter takes a closer look at the potential for four countries that are covered by the project under which th

232、is report has been issued:Bangladesh,Indonesia,Maldives and Samoa.2.1.Proposing notional targets for conservationand restoration of mangroves State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific35Mangrove cover losses have slowed significantly in recent years,providing an oppor

233、tunity to stop all losses.Direct human-driven losses have been targeted as these can be managed directly.It is estimated that human-driven losses account for 62 per cent of total losses(Goldberg and others,2020;and Leal and Spalding,2022).Over the past decade,from 2010 to 2020,420 km2 of mangroves w

234、ere lost in the Asia-Pacific region,of which 260 km2(62 per cent)could be attributed to the losses due to direct human impacts.To achieve zero direct human-driven mangrove loss,the loss rates should be gradually reduced.Assuming a linear reduction in human-driven losses,stopping ongoing losses would

235、 save an estimated 182 km2 of mangroves in the Asia-Pacific region,by 2030.To prevent further mangrove loss,it is crucial to protect them through sustainable conservation and management measures.Even though not all unprotected mangroves are under immediate threat,safeguarding them through long-term

236、commitments is essential.Studies indicate that safeguarding another 40 per cent(30000 km2)of the existing mangroves in the Asia-Pacific region by 2030 could help to contain potential emissions of 4.65 gigatons of carbon dioxide(CO2)and promote commercial fish productivity to a value of$143-183 billi

237、on annually(Leal and Spalding,2022).The status of mangrove protection varies significantly among the selected countries,and to some extent this explains the losses and gains of mangroves in these countries(Table 6).In Indonesia,in 2020,mangroves within protected areas accounted for 24.86 per cent of

238、 the total mangrove area,equalling 7,343.20 km2 out of 29,533.98 km2(GMW,n.d.).Notably,Bangladesh had 88.5 per cent of its mangroves protected,with 3,970.48 km2 in protected areas out of a total of 4,483.86 km2(GMW,n.d.).This high level of protection likely contributes to the overall increase in man

239、grove cover.Meanwhile,in the Maldives,only 23.63 per cent of the total mangrove area was within protected areas in 2020,with 23.00 hectares out of 97.34 hectares being protected(GMW,n.d.).Similarly,in Samoa,19.3 per cent of the mangroves were found in protected areas in 2020,accounting for 45.00 hec

240、tares out of a total of 232.18 hectares(GMW,n.d.).The overall regional potential restoration of mangrove forests in Asia and the Pacific is estimated at 1,350 km2 by 2030.This target is estimated to mitigate 70 per cent of recent losses(3,383 km2 of mangroves,Table 1),due to direct human activities

241、and contribute to 50 per cent of recovery of past losses.This restoration effort could help to store around 209 million tons of CO2.Since mangrove ecosystems are estimated to deliver approximately$193,843 in ecosystem services per hectare per year(Costanza and others,2014),the restoration 1,350 km2

242、of mangrove forests could yield$26.17 billion annually from the associated ecosystem services in the long run.RESTORABLE MANGROVE AREAS PREVENTING LOSSES AND DOUBLING PROTECTIONState of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific36A team of mangrove experts,representing institu

243、tions like the University of Cambridge,The Nature Conservancy,IUCN,the Global Mangrove Alliance,and others,utilized data from Global Mangrove Watch to create a map that traces the historical extent of mangroves from 1996 to 2020.They also pinpointed areas where mangroves have been lost and establish

244、ed a model to predict the factors conducive to restoration,enabling to identification of suitable locations for mangrove restoration by recognizing areas where mangroves once flourished and where environmental conditions still support restoration efforts(GMW,n.d.).This comprehensive assessment facil

245、itates the assessment of restoration potential by country(Table 6).In Indonesia,the cumulative mangrove area that has been lost amounts to 253,641 hectares.Within this loss,49,105 hectares,equivalent to 19 per cent,are categorized as non-restorable.Meanwhile,the remaining 204,536 hectares,accounting

246、 for 81 per cent of the total mangrove area loss,are considered restorable.These restorable mangrove areas made up 6.92 per cent of the entire mangrove area,in 2020.In Bangladesh,the total mangrove area lost has reached 28,516 hectares.Out of this loss,a significant portion,22,590 hectares or 79 per

247、 cent,is classified as non-restorable.The remaining 5,925 hectares,constituting 21 per cent of the overall mangrove area loss,are categorized as restorable.These restorable mangrove areas made up 1.32 per cent of the countrys entire mangrove area in 2020.In Samoa,the cumulative mangrove area that ha

248、s been lost amounts to 22 hectares.Among this loss,5.67 hectares,equivalent to 25 per cent,are categorized as non-restorable.Meanwhile,the remaining 16.39 hectares,accounting for 75 per cent of the total mangrove area loss,are considered restorable.These restorable mangrove areas made up 7 per cent

249、of the entire mangrove area,in 2020.Table 6.Restoration potential of lost mangrove areasIndonesiaBangladeshMaldivesSamoaArea(ha)PercentageArea(ha)PercentageArea(ha)Percentage Area(ha)PercentageMangrove area in 20202,953,398448,38697232Mangroves in protected areas734,32024.86397,04888.52323.634519.3T

250、otal mangrove area loss253,64128,51622Mangroves restoration potential score797582Non-restorable lost mangrove area49,105.4019.3622,590.6579.225.6725.71Restorable lost mangrove area204,536.1780.645,925.6520.7816.3974.33Source:Authors compilation from Global Mangrove Watch,“Global Mangrove Watch”,n.d.

251、Available at http:/www.globalmangrovewatch.org/State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific37Figure 9.Target increase in mangroves area by 2030Source:Sawaid Abbas,“Regional Assessment of the Status of Ecosystems as Nature-Based Solutions for Climate Action:Underscoring

252、the role of blue carbon ecosystems in Asia and the Pacific”,United Nations ESCAP,Environment and Development Division,Bangkok,December 2023.Note:The target increase in area is estimated by adding“reduction in expected losses by 2030”,and“recoverable losses from the lost mangroves area during 1996 to

253、 2020”.For detailed description of this calculation,refer to Abbas(2023).Note:The percentages in parentheses refer to target increase as proportion of area under mangroves in each country.Note:Countries with zero target increase in mangroves area are excluded from the table.Based on the analysis of

254、the mangrove restoration potential and the potential to stop mangrove losses in Asia and the Pacific,Figure 9 presents notional targets by percentage increase in mangrove area for member States in the Asia-Pacific region,indicating considerable potential especially in Australia,Indonesia,Myanmar and

255、 Pakistan in particular.NOTIONAL TARGETS FOR THE RESTORATION OF MANGROVES State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific382.2.Conservation and restoration of coral reefs CORAL REEF EXTENT IN SELECTED COUNTRIES Protecting at-risk coral reefs is of utmost importance,and hig

256、h-risk areas should be prioritized for conservation and immediate restoration efforts.Locations facing the combined impact of local and global stressors by 2030 or 2050,as well as those with critical or very high threats to coral reefs,require urgent recovery plans.Given the substantial ecosystem se

257、rvices provided by coral reefs,conserving and restoring high-risk areas could yield significant benefits,with a potential value of$4.05 trillion by 2030 and$5.14 trillion by 2050.Coral reefs are a vital part of Indonesias coastal regions,spanning approximately 2.04 million hectares,making it the lar

258、gest expanse among the target countries.Indonesias extensive coral reef coverage underscores the importance of preserving and protecting these ecosystems,not only for the country but for the entire marine environment of the Asia-Pacific region.Substantial coral reef areas can also be found in the co

259、astal regions of the Maldives,covering 262,184 hectares,as well as Samoa,where they span 22,904 hectares.The relatively compact landmasses of Maldives and Samoa accentuate the ecological importance and protective functions of their extensive coral reef systems.These regions are deserving of dedicate

260、d efforts to ensure their preservation,as these ecosystems play a pivotal role not only in the nations environmental health but also in maintaining the global ecological equilibrium.In contrast,Bangladeshs coastal areas are notably lacking in well-documented coral reef habitats.In terms of comparati

261、ve coverage of the three coastal ecosystems(mangroves,coral reefs and seagrass),Indonesia and Samoa exhibit the second highest proportion of coral reefs,while coral reefs dominate the coastal ecosystem with the highest coverage in the Maldives.State of Blue Carbon Ecosystems for Climate Action in As

262、ia and the Pacific39THREATS TO CORAL REEFS AND CONSERVATION PRIORITIESIN SELECTED COUNTRIES Indonesia,as one of the largest habitats for coral reefs,presents a pessimistic scenario where three-fourths of the coral reefs are expected to fall into the critical(8 per cent),very high(20 per cent),and hi

263、gh(44 per cent)threat categories by 2030,with a worsening outlook by 2050.These threats stem from a combination of local and global factors,including human pressures on coral reefs.Local threats addressed in this analysis encompass coastal development,watershed-based pollution,marine-based pollution

264、,damage,overfishing,and destructive fishing.Global threats include thermal stress,driven by warming sea temperatures leading to coral bleaching,and ocean acidification driven by increased CO2 levels resulting in reduced coral growth rates(Burke and others,2011).Maldives,in the current scenario,predo

265、minantly harbours coral reefs within a medium to low-risk category,and these reefs remain relatively stable in the projected outlook for 2030.This stability can be attributed primarily to the limited direct human influence on the quality of ocean water.However,under the 2050 projection,approximately

266、 35 per cent of the coral reefs in Maldives will face high(24 per cent)and very high(11 per cent)threats.In stark contrast,the coral reefs around Samoa are anticipated to be highly threatened by 2030.Most of the coral reefs along the north-western coasts of Samoa will be critically threatened,while

267、the coral in the southern and south-eastern coasts will be under very high threat by 2030.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific402.3.Conservation and restoration of seagrasses Carbon credit accounting methodologies for seagrass conservation and restoration projec

268、ts now exist,and widely recognized credits could provide financial incentives to protect seagrass ecosystems.An analysis conducted to evaluate the vulnerability of seagrass ecosystems to human impacts categorizes them into five distinct risk levels based on their exposure to direct and indirect huma

269、n influences.In the Asia-Pacific region,approximately 29 per cent of seagrass areas face higher combined human impact,with significant potential for targeted conservation and restoration.Protection could safeguard valuable ecosystem services(estimated at$1.118 trillion),and store some 444 Mt of carb

270、on storage,and contribute to nature-based solutions for CO2 mitigation.Nonetheless,ongoing research and data updates are imperative to ensure that conservation and management efforts are based on the latest insights into the regions seagrass ecosystems.In the coastal waters of Indonesia,the seagrass

271、 area spans 1.68 million hectares,making it the largest globally in terms of sheer coverage.However,when considering the proportion of seagrass relative to the total area of coastal ecosystems,including mangroves and coral reefs,seagrass makes up only 25 per cent(UNEP-WCMC and Short,2021).Another st

272、udy has reported that the seagrass area of Indonesia is around 3 million hectares with a carbon storage potential of 119.5 Mg C(ton of carbon)per hectare(Pham and Thi,2019),based on an average sequestration rate of 140 metric tons of C per hectare(Pendleton and others,2012;Serrano and others,2021).I

273、n the Maldives,seagrasses extend across 239,737 hectares,covering a proportion of the three ecosystems similar to coral reefs.In Samoa,the seagrass area is 97,289 hectares,surpassing the relative proportions of mangroves and coral reefs.Bangladesh exhibits the least amount of seagrass coverage and t

274、he lowest proportion compared to the other coastal ecosystems(Figure 10).In Bangladeshs oceanic waters,seagrass presence is nearly non-existent.SEAGRASS EXTENT IN SELECTED COUNTRIES State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific41An overlay analysis of the seagrass sighti

275、ng locations with the Combined Human Impact(CHI)(Halpern and others,2008,2019)to the marine ecosystems shows the exposure of seagrass ecosystem to the direct and indirect human impacts.The results are categorized into five classes of risk including Critical(4),Very High(3-4),High(2-3),Medium(1-2),an

276、d Low(1)(Figure 10).Details on the analysis are given in section 2.3-Conservation and Restoration of Seagrasses.THREATS TO SEAGRASS AND CONSERVATION PRIORITIESIN SELECTED COUNTRIESFigure 10.Categorization of the Combined Human Impact on seagrasses in the Asia-Pacific region countries including Indon

277、esia,Bangladesh,Maldives,and SamoaSource:Authors compilation from B.S.Halpern,and others,“A Global Map of Human Impact on Marine Ecosystems”,Science,vol.319,No.5865(February 2008).Available at https:/doi.org/10.1126/science.1149345;and B.S.Halpern,and others,“Recent pace of change in human impact on

278、 the worlds ocean”,Scientific Reports,vol.9(August 2019).Available at https:/doi.org/10.1038/s41598-019-47201-9;and United Nations Environment Programme(UNEP),UN Environment World Conservation Monitoring Centre(UNEP-WCMC),and Short,F.(2021).Global distribution of seagrasses(version 7.1).Seventh upda

279、te to the data layer used in Green and Short(2003).Cambridge.Available at https:/doi.org/10.34892/x6r3-d211.Note:Considering the small sample sizes available for Maldives and Samoa,the global assessments might not be relevant at the local scale threats and risks to the seagrass habitat.These statist

280、ics could be revised provided localized data is available.Note:An overlay analysis of the seagrass sighting locations with the Combined Human Impact(CHI)on the marine ecosystems shows the exposure of the seagrass ecosystem to direct and indirect human impacts.State of Blue Carbon Ecosystems for Clim

281、ate Action in Asia and the Pacific42Reduction of potential losses and degradation from seagrass could potentially prevent emissions of around 224 MtCO2 in Indonesia,40 MtCO2 in Maldives and 3.6 MtCO2 in Samoa(Abbas,2023).This assessment should be understood as highly conservative,being derived from

282、an analysis of overlays of seagrass locations(UNEP-WCMC and Short,2021)with the exposure of seagrass ecosystems to direct and indirect human impacts(Halpern and others,2008).The threats and risks to seagrass habitat at the local level need to be better understood.Sea level rise,which could exceed 2

283、metres by 2100,is already impacting coastal communities in the Asia-Pacific region,causing flooding,erosion,and saltwater intrusion and disturbances to coastal ecosystems.Most islands in the Pacific are subsiding due to the extraction of groundwater(Gravelle and others,2023),magnifying these impacts

284、.The low adaptive capacity of the Pacific Island countries to climate change poses a serious risk to coastal ecosystem services and infrastructure(ADB,2022).It is crucial to emphasize the lack of existing literature and assessments concerning the ever-changing nature of these seagrass beds.This know

285、ledge deficit underscores a significant gap in our understanding of nature-based solutions and widens the untapped potential for investments in conservation and restoration.Addressing these gaps is imperative for harnessing the full ecological and climate-regulating potential of these invaluable sea

286、grass ecosystems.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific43CONCLUSION AND RECOMMENDATIONSCHAPTER 3State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific443.1.ConclusionThis assessment underscores the profound importance of blue carbon ecosystems

287、in the Asia-Pacific region as vital components of nature-based solutions to combat the adverse effects of climate change.This region harbours approximately 50 per cent of the worlds mangroves,a quarter of the global seagrass,and over three-quarters of the worlds coral reefs,all of which have a profo

288、und influence on climate regulation,socioeconomic well-being,and on the livelihoods of coastal communities,particularly those residing in low-lying areas.Regrettably,these exceptionally diverse and globally significant resources in the region are under threat,with significant depletion attributed to

289、 both direct human impacts on a local scale,and indirect human influences,such as climate change on a global or regional scale.A substantial portion of these ecosystem resources has already been lost or degraded,while significant proportions remain vulnerable to changing environmental conditions and

290、 direct human pressures.Fortunately,there is a unique opportunity for the conservation and restoration of these ecosystem services to ensure the continued economic and climate benefits.Nevertheless,knowledge about these ecosystems is at different stages of development.Monitoring and modeling regardi

291、ng mangroves has advanced with spatially-referenced data for carbon sequestration,precise area estimation,and advanced assessment of the potential for habitat restoration.In contrast,seagrass ecosystems are still in their early stages of mapping and monitoring,lacking comprehensive data regarding th

292、eir extent,temporal changes,and degradation.Extensive research is imperative for the development of market-based incentives for protection,supported by focused monitoring and modelling efforts.This scenario presents a remarkable investment opportunity,not only to safeguard and conserve these ecosyst

293、ems to prevent the release of stored carbon into the atmosphere,but also to promote ecosystem-based adaptation,benefiting the millions of people who reside in low-lying coastal areas,and rely on fisheries in the Asia-Pacific region.Moreover,this assessment underscores the importance of developing co

294、mprehensive monitoring,mapping,and modelling methodologies for national and local assessments in various cycles across four different countries.These methodologies are critical for understanding the driving forces and dynamics of these ecosystems,and for creating models that can inform regional-scal

295、e assessments.Furthermore,this assessment unveils the reality of the potential of blue carbon investment as a nature-based solution as well as the challenges for Indonesia,Bangladesh,Maldives,and Samoa.It showcases how the restoration of mangroves can effectively sequester substantial carbon,provide

296、 invaluable ecosystem services,and yield substantial returns on investments.The Asia-Pacific region has a substantial demand for nature-based solutions,contributing more than 30 per cent of all global nature-based credits,amounting to 85 million tons.Nonetheless,investments in nature-based solutions

297、 have primarily concentrated on terrestrial ecosystems,like forests,leaving the critical coastal ecosystems of mangroves,seagrass,and coral reefs somewhat overlooked.Integrating blue carbon into the Nationally Determined Contributions(NDCs)of the regions countries presents a series of challenges tha

298、t require immediate attention.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific453.2.Recommendations This report recommends national efforts to set and/or assess targets for restoration of blue carbon ecosystems.The notional targets for mangrove restoration proposed in this

299、report for 24 Asia-Pacific countries and territories can provide input to national efforts to define targets for mangrove restoration,where they do not exist and for re-assessing existing targets,where targets have already been defined.Such targets will help integrate blue carbon into the second cyc

300、le of NDC updates(NDCs 3.0),a process which will require transparent and meaningful engagement with local governments and communities.It also invites regional action for accelerated investment in protection of blue carbon ecosystems.Ecosystem health assessment must be stepped up.Realistic and strate

301、gically-defined restoration targets that take into account the exposure of blue carbon ecosystems to natural and human-made hazards and the ecosystem services provided,are needed.Regional action may also help develop regional,national and local enabling environment to increase investments in the res

302、toration and preservation of mangroves,coral reefs,and seagrasses to leverage their full potential for carbon sequestration and climate adaptation.Other opportunities for strengthening regional cooperation to enhance the blue carbon ecosystems and their invaluable services for mitigation and adaptat

303、ion efforts in the region include establishing a regional network of blue carbon experts and practitioners to:Undertake further research to understand and unlock the full ecological and climate-regulation potential of blue carbon ecosystems in the region.Map,model and monitor the carbon sequestratio

304、n services of marine ecosystems,especially seagrasses through collecting data and scientific evidence on their extent and dynamics,and land-based environmental stressors that compromise their health.Explore realistic,yet ambitious science-based targets for restoration and preservation.Undertake nati

305、onal landscape restoration planning,and target setting for nationally determined contributions based on the proposed notional targets.While there is substantial potential for investment in blue carbon,the complexity of the challenges faced and the critical importance of the other ecosystem services

306、provided by blue carbon ecosystems for climate adaptation,underline the need to fully empower local communities,indigenous peoples,and local governments as co-investors in conservation and restoration efforts.State of Blue Carbon Ecosystems for Climate Action in Asia and the Pacific46ReferencesAbbas

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