Impacts and risks of changing ocean on marine ecosystems and dependent communities and related responses

doi:10.12006/j.issn.1673-1719.2020.028

Abstract

Abstract:

The IPCC special report on the ocean and cryosphere in a changing climate (SROCC) presents an assessment of the changes in the ocean climate, their impacts on ecosystems and human society, related risks, and responses. The results show that the physical and chemical properties of the ocean, such as warming, acidification, deoxygenation, and reduction of nutrients referred to ocean climate hazards, have changed significantly over the past decades (high confidence). This is affecting the marine ecosystems from the surface to sea floor and having negative consequences on human society and sustainable development (high confidence), e.g., the changes in biogeography of organisms ranging from phytoplankton to benthonic organism, consequently reduction in primary production and maximum catch potential of fish stocks as well as food provision etc. It is obvious that, globally, almost all marine ecosystems are expected to be at high or very high risk by the end of the 21st century under compound impacts of climate change and non-climatic anthropogenic factors, with increasing greenhouse gas emission (from RCP2.6 to RCP8.5 scenario) (high confidence). In particular, the warm water coral reefs are projected to disappear by 70%-90% and larger than 99% at global warming of 1.5℃ and 2℃, respectively (very high confidence). However, the effectiveness of many ocean-based climate mitigation is smaller or have higher uncertainties, and the capacity of many adaptation approaches for risk reduction, especially under the RCP8.5 scenario, are also limited. It is noted that RCP2.6 has a lower level of risk for all types of marine ecosystems than RCP8.5 (very high confidence). These highlight the critical importance of mitigation and the increasing effectiveness of the different type portfolios of mitigation and adaptation to climate change.

Key words: Climate change, Ocean, Marine ecosystems, Human society, Impact, Risk, Response

CAI Rong-Shuo,HAN Zhi-Qiang,YANG Zheng-Xian. Impacts and risks of changing ocean on marine ecosystems and dependent communities and related responses[J]. Climate Change Research, 2020, 16(2): 182-193.

Figures/Tables 7

Fig. 1 Synthesis of observed regional hazards and impacts in the ocean assessed in SROCC[1, 3-4]

Fig. 2 Simulated global changes (relative to the 1850-1900 period) for surface pH, O2 concentration averaged over 100-600 m depth, upper 100 m nitrate concentrations and NPP integrated over the top 100 m[3] (a, d, g, j) over the period of 1900-2100, (b, e, h, k) spatial patterns of simulated change averaged over 2081-2100 for RCP8.5, (c, f, i, l) time series of the percentage of total uncertainty ascribed to internal variability uncertainty, model uncertainty, and scenario uncertainty in projections of global annual mean changes

Fig. 3 Map of the dominant limiting resource for primary productivity[3] (colouring of the circles indicates the primary limiting nutrients of N (blue), P (black), Fe (red), Co (yellow) and Zn (cyan). Divided circles indicate potentially co-limiting nutrients, for example, a red-blue divided circle indicates Fe-N co-limitation)

Fig. 4 Evidence of climate change responses of marine organisms such as phytoplankton, invertebrate, fishes, and other species which mainly include mammals, seabirds and marine reptiles, to changes in ocean conditions under climate change [3](a) evidence of interactive effects (including synergistic and antagonistic) of multiple climatic hazards, (b, c, d) observations on changes in latitudinal range, (e, f, g, h) phenology (for b-h, each bar represents one record variability uncertainty, model uncertainty, and scenario uncertainty in projections of global annual mean changes)

Tab.1 Projected changes in total animal biomass by the mid- and end of the 21st century under RCP2.6 and RCP8.5[3] (The very likely ranges of the projections (95% confidence intervals) are provided. Reference period is the present day (1986-2005))

Fig. 5 Over the ocean the projected changes under RCP8.5 by 2100 in catch potential, and on land, each countries and regions current proportion of fish micronutrient intake relative to the total animal sourced food (ASF)[3] (The colour scale on land is the proportion of fish micronutrient intake relative to the total ASF; the scale on the ocean is projected change in maximum catch potential)

Fig. 6 Risk scenarios for open ocean (a) and coastal ecosystems (b) based on observed and projected climate impacts (Present day corresponds to the 2000s, whereas the different greenhouse emissions scenarios RCP2.6 and RCP8.5 correspond to year 2100). Multiple climatic hazards are considered, including ocean warming, deoxygenation, acidification, changes in nutrient, particulate organic carbon flux and sea level rise. The projected changes in sea surface temperature from an ensemble of general circulation models (left panels) indicate the level of ocean changes under RCP2.6 and RCP8.5. Impact/risk levels do not consider human risk reduction strategies such as societal adaptation, or future changes in non-climatic hazards. The grey vertical bars indicate the transition between the levels of risks, with their confidence level based on expert judgment [3]

References

[1]	IPCC. Summary for policymakers [M/OL]// IPCC. Special report on the ocean and cryosphere in a changing climate. 2019 [ 2020-02-10]. https://www.ipcc.ch/srocc/
[2]	蔡榕硕, 谭红建, 郭海峡 . 中国沿海地区对全球变化的响应及风险研究[J]. 应用海洋学学报, 2019,38(4):514-527.
[2]	Cai R S, Tan H J, Guo H X . Responses and compound risks of the coastal China areas to global change[J]. Journal of Applied Oceanography, 2019,38(4):514-527 (in Chinese)
[3]	Bindoff N L, Cheung W W L, Kairo J G, et al. Changing ocean, marine ecosystems, and dependent communities [M/OL]// IPCC. Special report on the ocean and cryosphere in a changing climate. 2019 [ 2020-02-10]. https://www.ipcc.ch/srocc/
[4]	王朋岭, 黄磊, 巢清尘 , 等. IPCC SROCC的主要结论和启示[J]. 气候变化研究进展, 2020,16(2). DOI: 10.12006/j.issn.1673-1719.2019.240.
[4]	Wang P L, Huang L, Chao Q C , et al. The main content and insights of IPCC special report on the ocean and cryosphere in a changing climate (SROCC)[J]. Climate Change Research, 2020,16(2). DOI: 10.12006/j.issn.1673-1719.2019.240 (in Chinese)
[5]	Rhein M, Rintoul S R, Aoki S , et al. Observations: ocean [M] //IPCC. Climate change 2013: the physical science basis: contribution of working group I to the fifth assessment report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press, 2013
[6]	Collins M, Knutti R, Arblaster J , et al. Long-term climate change: projections, commitments and irreversibility [M] //IPCC. Climate change 2013: the physical science basis: contribution of working group I to the fifth assessment report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press, 2013
[7]	Durack P J . Ocean salinity and the global water cycle[J]. Oceanography, 2015,28(1):20-31
[8]	Hoegh-Guldberg O, Cai R S, Poloczanska E S , et al. The ocean [M] //IPCC. Climate change 2014: impacts, adaptation, and vulnerability: contribution of working group II to the fifth assessment report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press, 2014
[9]	Pauly D, Zeller D . Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining[J]. Nature Communications, 2016,7:1-9. DOI: 10.1038/ncomms10244
[10]	McLeod E, Chmuraet G L, Bouillon S , et al . A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2[J]. Frontiers in Ecology and the Environment, 2011,9(10):552-560. DOI: 10.1890/110004
[11]	Duarte C M, Hendriks I, Moore T S , et al. Is ocean acidification an open-ocean syndrome? Understanding anthropogenic impacts on seawater pH[J]. Estuaries and Coasts, 2013,36(2):221-236
[12]	Sippo Z J, Lovelock E C, Santos I R , et al. Mangrove mortality in a changing climate: an overview[J]. Estuarine, Coastal and Shelf Science, 2018: 215, 241-249. DOI: 10.1016/j.ecss.2018.10.011
[13]	Hoegh-Guldberg O, Jacob D, Taylor M , , et al. Impacts of 1.5℃ global warming on natural and human systems [M/OL]//IPCC. Global warming of 1.5℃. 2018 [ 2020-02-02].https://www.ipcc.ch/site/assets/uploads/sites/2/2019/06/SR15_Chapter3_Low_Res.pdf
[14]	Fine M, Cinar M, Voolstra C R , et al. Coral reefs of the Red Sea: challenges and potential solutions[J]. Regional Studies Marine Science, 2019,25. DOI: 10.1016/j.rsma.2018.100498
[15]	Sumaila U R, Lam V, Miller M M , et al. Winners and losers in a world where the high seas is closed to fishing[J]. Scientific Reports, 2015,5(8481). DOI: 10.1038/srep08481
[16]	Free C M, Thorson J T, Pinsky M L , et al. Impacts of historical warming on marine fisheries production[J]. Science, 2019,363(6430):979. DOI: 10.1126/science.aau1758
[17]	Cartapanis O, Galbraith E D, Bianchi D , et al. Carbon burial in deep sea sediment and implications for oceanic inventories of carbon and alkalinity over the last glacial cycle[J]. Climate of the Past, 2018,14(11):1819-1850. DOI: 10.5194/cp-14-1819-2018