海洋的变化及其对生态系统和人类社会的影响、风险及应对

doi:10.12006/j.issn.1673-1719.2020.028

摘要/Abstract

摘要：

IPCC《气候变化中的海洋和冰冻圈特别报告》评估了全球和区域海洋的气候变化及其对生态系统和人类社会的影响、风险及应对措施。结果表明,近几十年来,海洋的物理和化学性质发生了明显变化,如升温、酸化、脱氧和营养盐减少等气候致灾因子（事件）的危害（险）性不断加剧（高信度）。这种变化正在影响从上层到底层的海洋生态系统和人类社会的可持续发展,如海洋初级生产力的下降、物种地理分布的变迁、渔业资源潜在渔获量的下降以及食品供应的减少（高信度）。在气候变化与非气候人为干扰因素的综合影响下,随着温室气体排放的增加（从RCP2.6到RCP8.5情景）,到21世纪末,几乎所有类型的海洋和海岸带生态系统将处于高或很高的风险水平（高信度);其中,暖水珊瑚礁生态系统尤其严重,如果全球升温1.5℃和2℃,将分别消失70%~90%和99%以上（很高信度）。然而,当前多种减缓气候变化的海洋应对措施的作用较小,有的可能带来生态危险,而许多降低气候风险的海洋适应措施的作用也很有限,特别是在RCP8.5情景下的作用更小;未来海洋生态系统的风险水平在RCP2.6情景下均低于RCP8.5情景（很高信度)。因此,这凸显了减缓气候变化尤其是减缓和适应气候变化综合治理的重要性。

关键词: 气候变化, 海洋, 生态系统, 人类社会, 影响, 风险, 应对

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

蔡榕硕,韩志强,杨正先. 海洋的变化及其对生态系统和人类社会的影响、风险及应对[J]. 气候变化研究进展, 2020, 16(2): 182-193.

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.

图/表 7

图1 观测到的海洋变化及其对生态系统和人类社会的影响[1,3-4] 注：*表示东边界上升流区（本格拉寒流、加那利寒流、加利福尼亚寒流和秘鲁寒流）。

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

图2 全球海洋表层的pH值、100~600 m层平均的溶解氧（O2)、0~100 m层的硝酸盐（NO3）浓度和净初级生产力（NPP）的变化（相对于1850—1900年）[3]（a,d,g,j）1900—2100年模拟结果,（b,e,h,k）RCP8.5情景下2081—2100年模拟结果,（c,f,i,l）由内部变率、模式和情景的不确定性引起的总不确定性的百分比组成的时间序列注：（a,d,g,j）图中实线为多模式平均值,阴影表示90%信度区间。

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

图3 全球海洋初级生产力的空间分布及其营养盐限制[3] 注：两种不同颜色如红、蓝色的圆点表示不同（Fe-N）营养盐因素的共同限制。

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)

图4 观测到的海洋生物对海洋气候变化的响应[3](a)多种气候致灾因子（事件）相互作用对海洋生物（浮游植物、无脊椎动物、鱼类,以及哺乳动物、海鸟和爬行动物等其他物种）的影响效应,(b,c,d) 观测到的上述海洋物种分布范围变迁,(e,f,g,h)物候变迁（(a)图中黑点表示信度水平,无黑点表示信息不足以得出结论;其他图中柱形代表一个记录）

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)

表1 RCP2.6和RCP8.5情景下相对于1986—2005年21世纪中叶和末期海洋动物总生物量变化预估[3]

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))

图5 预估的RCP8.5情景下2100年全球渔业潜在渔获量的变化和当前鱼类在世界每个国家或地区动物性食品中的比重[3]

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)

图6 RCP2.6和RCP8.5两种情景下海洋(a)和海岸带生态系统(b)暴露于海洋升温、酸化和脱氧等多种气候致灾因子下的风险水平[3]（(a)图表示相对工业革命前,1950—2100年全球平均海表面温度变化情景;未考虑人类减少风险的适应对策或未来非气候致灾事件的变化;灰色竖条表示不同风险水平之间的过渡以及基于专家判定的信度水平）

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]

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