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1.
IPCC《气候变化中的海洋和冰冻圈特别报告》评估了气候变化对全球、区域海平面变化和极端海面(极值水位)升高的贡献,以及海平面上升对低海拔(小鱼10 m)岛屿、沿海地区和社会的影响及相关的风险。评估表明,全球变暖背景下,全球平均海平面上升的证据是确凿的,且明显加速(高信度),极端海面高度升高,主要是由陆地冰川和冰盖融化以及海洋热膨胀引起,且前者的贡献已大于后者(很高信度);与此同时,海洋变暖速率倍增,强热带气旋、风暴潮增多,极值水位重现期缩短;至21世纪末,全球海平面还将上升约0.43 m(温室气体低排放情景,RCP2.6)和0.84 m(高排放情景,RCP8.5)(中等信度),很多沿海地区当前较少发生的百年一遇的极值水位将变为一年一遇或更频繁,而对于许多沿海低洼地而言,类似事件甚至在21世纪中叶就可能发生(高信度)。评估还表明,持续上升的海平面、趋于频发的极值水位,以及人为地面沉降等因素,增加了沿海社会-生态系统的暴露度和脆弱性;并且,与海平面上升有关的危害(险)性事件,如海岸侵蚀、洪灾、盐碱化和生境退化等将显著增加(高信度)。报告指出,如未采取充分的适应海平面上升的措施,在RCP8.5情景下,沿海大城市、城市环礁群岛、热带农业三角洲地区和北极沿岸社区将处于高或很高的灾害风险中(高信度)。  相似文献   

2.
基于参加国际耦合模式比较计划第5阶段(CMIP5)的29个全球气候模式开展的历史气候模拟和3种典型浓度路径(RCP2.6、RCP4.5、 RCP8.5)下21世纪气候预估的结果,分析了单个模式和多模式集合平均(MME)的21世纪全球与中国年平均地表气温(ASAT)变化特征及2℃升温阈值的出现时间。多模式集合平均的结果显示:全球和中国年平均地表气温均将继续升高,21世纪末的升温幅度随着辐射强迫的增大而增大。RCP2.6情景下,年平均地表气温增幅先升高后降低,全球(中国)年平均地表气温在2056年(2049年)达到升温峰值,21世纪末升温1.74℃(2.12℃);RCP4.5情景下,年平均地表气温在21世纪前半叶逐渐升高,之后升温趋势减缓,21世纪后期趋于平稳,21世纪末全球(中国)年平均地表气温增幅为2.60℃(3.39℃);RCP8.5情景下,21世纪年平均地表气温快速升高,21世纪末全球(中国)年平均地表气温增幅为4.75℃(6.55℃)。全球平均的年平均地表气温增幅,在RCP2.6情景下没有超过2℃,RCP4.5和RCP8.5情景下分别在2047和2038年达到2℃。RCP2.6、RCP4.5和RCP8.5情景下中国年平均地表气温增幅连续5 a不低于2℃的时间分别在2032、2033和2027年,明显早于全球平均。任一典型浓度路径情景下,达到2℃升温的时间,北半球同纬度地区早于南半球,同半球高纬度地区早于低纬度地区,同纬度地区陆地早于海洋。3种不同典型浓度路径情景下21世纪全球和中国年平均地表气温将继续升高这一结果是可信的,RCP4.5和RCP8.5情景下全球和中国年平均地表气温增幅超过2℃的结果模式之间有较高的一致性。多模式预估的全球和中国年平均地表气温升幅和不同幅度升温的出现时间均存在一定的不确定性,预估结果的不确定性随预估时间的延长而增大;相同情景下,中国年平均地表气温预估的不确定性大于全球。  相似文献   

3.
利用CMIP5耦合气候模式的模拟结果,分析了不同排放情景下1.5℃和2℃升温阈值出现的时间。多模式集合平均结果表明:RCP2.6、RCP4.5和RCP8.5排放情景下,全球地表温度将分别在2029年、2028年和2025年达到1.5℃升温阈值;RCP2.6情景下直至21世纪末期都未达到2℃升温阈值,RCP4.5和RCP8.5排放情景下达到2℃升温阈值的时间分别为2048年和2040年。伴随着排放情景的升高,完成从1.5℃升温阈值到2℃升温阈值所需要的时间缩短。区域尺度上,达到同一升温阈值的时间主要表现为陆地比海洋早,且陆地对排放情景差异的敏感性相对较差,而海洋达到升温阈值的时间则随着排放情景的升高而明显提前。中国达到相应升温阈值的时间要早于全球,且以东北和西北地区出现的时间最早。  相似文献   

4.
利用CMIP5耦合模式RCP2.6、RCP4.5和RCP8.5情景预估结果,以1890一1900年为基准气候,确定了2℃全球变暖时间、对应时期青藏高原平均气候和极端气候事件变化幅度,多模式集合平均结果表明:RCP2.6、RCP4.5和RCP8.5情景下2℃全球变暖分别发生在2063年、2040年和2036年;对应着2℃全球变暖,三种情景下青藏高原平均气温分别升高2.99℃、3.22℃和3.28℃,均超过全球2℃的升温水平;年降水量亦增加,分别增加8.35%、7.16%和7.63%。受气温升高和降水量增多影响,RCP4.5情景下霜冻日数、冰封日数减少,暖夜日数、暖昼日数增多;RCP4.5情景下中雨日数、强降水量、降水强度均增加,持续干期天数减少。从各地平均气候和极端气候事件变化结果来看,柴达木盆地是青藏高原气候变化的敏感区。  相似文献   

5.
研究地球工程对海洋酸化的影响对于评估地球工程对全球气候和环境的影响有重要意义。文中使用中等复杂程度的地球系统模式,模拟了典型CO2高排放情景RCP8.5下,实施太阳辐射管理地球工程对海洋表面的pH和文石(碳酸钙的一种亚稳形态)饱和度的影响,并定量分析了各环境因子对海洋酸化影响的机理。模拟结果表明,在RCP8.5情景下,到2100年,相对于工业革命前水平,全球海洋表面平均pH下降了0.43,文石饱和度下降了1.77。相对于RCP8.5情景,2100年地球工程情景下全球海洋表面平均pH增加了0.003,而文石饱和度降低了0.16。地球工程通过改变溶解无机碳、碱度、温度等环境因子影响海洋酸化。相对于RCP8.5情景,实施地球工程引起的溶解无机碳浓度的增加使pH和文石饱和度均减小,碱度的增加使pH和文石饱和度均增大,温度的降低使pH增大而使文石饱和度减小。总体而言,太阳辐射管理地球工程可以降低全球温度,但无法减缓海洋酸化。  相似文献   

6.
IPCC第六次评估报告(AR6)第二工作组报告第三章开展了气候变化对海洋的影响和风险,以及生态系统及其服务功能、脆弱性和适应评估。AR6明确指出,人为气候变化已经并将继续显著地改变全球和区域海洋的气候影响驱动因子,包括海温升高、海平面上升、海洋酸化和缺氧,以及营养盐浓度变化等海洋物理和化学因子。例如,20世纪80年代以来全球海洋热浪发生的频率已增加了1倍,到21世纪末期可能增加4~8倍。气候影响驱动因子的变化已经对海洋和海岸带生态系统造成了广泛而深远的影响:1)海洋变暖使得海洋物种自1950年代以来以(59.2±15.5) km/(10 a)的速率向极地方向迁移,导致热带海域生物量减少,中纬度海区热带化,极地和亚极地海区浮游植物生长期提前;2)频繁发生的海洋热浪事件已经接近甚至超过了某些海洋生物的耐受极限或其气候临界点,如暖水珊瑚的大规模白化、死亡,海草和大型海藻的大面积消失;3)海洋变暖、缺氧和酸化使得河口区生物群落结构改变,赤潮等有害藻华事件频发,近海和大洋浮游植物生物量和初级生产力下降;4)海平面上升导致海岸带红树林、盐沼和海草床等生态系统的退化;5)未来全球海洋生态系统面临的风险将不断加剧,尤其是在热带和北冰洋海区。其中,当全球升温1.5℃时(最快到21世纪40年代,SSP5-8.5情景),暖水珊瑚礁预计将减少70%~90%;当升温2℃时,几乎所有的(>99%)暖水珊瑚礁将会消失。目前人类社会采取的一些措施(如建立海洋保护区和红树林生态修复)已越来越不能应对日益增长的气候风险,迫切需要发展变革性的行动措施,推动海洋生态系统恢复力的发展,并需尽快采取强有力的减排措施以减缓全球变暖的影响。  相似文献   

7.
研究目的:本文采用CMIP5多模式的集合平均,针对多种排放情景,估算了丝绸之路核心区达到1.5度和2度温升的时间,比较了全球平均温度达到1.5度和2度温升阈值时丝绸之路核心区的平均气候和极端气候指标的变化。创新要点:中国西部和中亚位于古丝绸之路核心区,是连接东西方的桥梁。1.5度和2度温控目标的设定,是国际社会应对全球变暖的重要举措。理解在上述增暖阈值下丝绸之路核心区平均气候和极端气候的可能变化,将为一带一路战略的实施提供重要科学参考。研究方法:CMIP5多模式集合平均重要结论:相较于当前气候态(1986–2005年),在四种排放情景下,即RCP2.6、RCP4.5、RCP6.0和RCP8.5,CMIP5多模式集合预估的丝绸之路核心区到21世纪末将分别增温1.5、2.9、2.6和6.0°C。在四种排放情景下,年平均降水较之当前气候态均显著增加,其中在RCP8.5情景下增加约14%。四种排放情景下的预估结果,均显示丝绸之路核心区将在2020年前温升达到1.5°C。在RCP8.5情景下,该地区将在2020年代温升达到2.0°C,而在RCP4.5情景下,温升达到2.0°C的时间则推迟到2030年代。比较全球温升1.5和2.0°C的气候变化,发现全球额外升温0.5°C(较之1.5°C温升阈值)将导致丝绸之路核心区升温0.73°C(0.49–0.94°C),高于全球平均温度的变化,极端热浪的天数将增加4.2天,年平均降水增加2.72%(0.47%–3.82%),而连续干旱日数的变化则具有区域依赖性。  相似文献   

8.
以全球气候模式NorESM1-M产生的RCP2.6、RCP4.5、RCP6.0、RCP8.5气候变化情景数据和原环保部推荐的土壤风蚀扬尘计算方法,模拟分析了未来气候变化对河北坝上砂粘壤土、粘壤土、壤粘土、砂壤土、砂粘土和风沙土草地土壤风蚀扬尘总可悬浮颗粒物(Total Suspended Particle,TSP)、PM10和PM2.5的季节及年排放速率的影响。结果表明:气候变化影响下坝上地区气温上升,年降水量和风速波动较大、并存在上升和下降的趋势。相比基准情景,在RCP2.6、RCP4.5、RCP6.0和RCP8.5情景下,各土壤风蚀扬尘TSP、PM10和PM2.5季节排放速率在春季分别高15%、47%、28%和46%;秋季分别高17%、54%、45%和38%;冬季分别低36%、42%、39%和44%;夏季,在RCP2.6情景下低1%,在RCP4.5、RCP6.0和RCP8.5情景下分别高14%、3%和7%;未来气候变化情景下,各土壤风蚀扬尘TSP、PM10和PM2.5年排放速率分别高25%、54%、35%和54%。基准和未来气候变化情景下,土壤风蚀扬尘TSP、PM10和PM2.5的季节和年排放速率及其差异从高到低均依次为砂粘壤土、风沙土、砂壤土、粘壤土、壤粘土和砂粘土。表明未来气候变化将使河北坝上地区草地土壤风蚀扬尘排放速率增加,但存在季节和气候变化情景方面的差异。  相似文献   

9.
利用1981—2010年历史气象数据和2031—2060年(RCP2.6和RCP8.5)气候情景数据,根据橡胶寒害等级指标,结合插值分析、提取分析和地图代数等空间分析方法,研究在未来气候情景下我国橡胶树寒害事件的变化特征。结果表明:(1) RCP2.6和RCP8.5气候情景下2031—2060年我国橡胶种植适宜区基本呈现寒害发生降低的趋势,其中次适宜区(III)和局部可植区(IV)的降低幅度较为明显,有向高一等级适宜区转化的趋势。(2)我国橡胶树寒害中心的纬度,由1981—2010年的22.5°~23.5°N向北移动至2031—2060年RCP2.6情景下的24.0°~24.5°N和RCP8.5情景下的23.5°~24.0°N。(3) 2种气候情景下,2031—2060年我国海南、广西、广东、福建等植胶区橡胶树寒害发生概率(较基准时段1981—2010年)主要呈现降低趋势,云南植胶区在2种气候情景下有明显的差异,表现为RCP2.6情景下,轻度和特重寒害呈现降低趋势,中度和重度寒害呈现增加趋势;RCP8.5情景下,轻度和重度寒害呈现降低趋势,中度和特重寒害呈现增加趋势。(4)对比2种气候情景较基准时段的变化情况,RCP2.6情景对橡胶树轻度和特重寒害影响较大,RCP8.5情景对橡胶树中度和重度寒害影响较大。  相似文献   

10.
本文基于耦合模式比较计划第5阶段(CMIP5)的17个全球气候模式,确定了1.5℃温升(相对于1861-1880年)的发生时间,预估了全球升温1.5℃时,北半球冻土和积雪的变化,并对预估结果的不确定性进行了讨论。结果表明,全球平均地表温度在3种排放情景下(RCP2.6,RCP4.5,RCP8.5)分别于2027、2026、2023年达到1.5℃阈值。当全球升温1.5℃,北半球多年冻土南界北移1°~3.5°,冻土退化主要发生在中西伯利亚南部。多年冻土面积在全球升温1.5℃时,在RCP2.6、RCP4.5和RCP8.5排放情景下较1986-2005年分别减少约3.43×106 km2(21.12%)、3.91×106 km2(24.10%)和4.15×106 km2(25.55%);北半球超过一半以上的区域雪水当量减少,只在中西伯利亚地区略微增加;北美洲中部、欧洲西部以及俄罗斯西北部减少较显著,减少约40%以上。青藏高原多年冻土面积在RCP2.6、RCP4.5以及RCP8.5排放情景下分别减少0.15×106 km2(7.28%)、0.18×106 km2(8.74%)和0.17×106 km2(8.25%)。青藏高原冬、春季雪水当量分别减少约14.9%和13.8%。  相似文献   

11.
Most climatological studies characterize the future climate change as the evolution between a fixed current baseline and the future. However, as climate continues to change, ecosystems and societies will need to continuously adapt to a moving target. Here, we consider indicators of the pace of temperature change estimated from CMIP5 projections of an ensemble of climate models. We define the pace as a difference in relevant metrics between two successive 20-year periods, i.e. with a continually moving baseline. Under the strongest emission pathway (RCP8.5), the warming rate strongly increases, and peaks before 2080. All latitudes experience at least a doubling in the warming rate compared to the current period. Significant shifts in temperature distributions above twice the standard deviation between two successive 20-year periods expand from 9 % of continents on average currently to 41 % by 2060 onwards. In these regions, a warm year with a return period of about 50 years would become quite common 20 years later. The fraction of the world population exposed to such shifts will grow from 8 % to about 60 % on average, i.e. 6 billion people. Tropical areas are strongly affected, especially West Africa and South-East Asia. Low mitigation (RCP6.0) limits the warming rate to current values. Medium mitigation (RCP4.5) even reduces population exposure to significant shifts in temperature distributions to negligible values by the end of the century. Strong mitigation (RCP2.6) is the only option that generates a return to values similar to the historical period for all our indicators related to the pace of temperature change. This alternative way to analyze climate projections can yield new insights for the climate impacts and adaptation communities.  相似文献   

12.
We present climate responses of Representative Concentration Pathways (RCPs) using the coupled climate model HadGEM2-AO for the Coupled Model Intercomparison Project phase 5 (CMIP5). The RCPs are selected as standard scenarios for the IPCC Fifth Assessment Report and these scenarios include time paths for emissions and concentrations of greenhouse gas and aerosols and land-use/land cover. The global average warming and precipitation increases for the last 20 years of the 21st century relative to the period 1986-2005 are +1.1°C/+2.1% for RCP2.6, +2.4°C/+4.0% for RCP4.5, +2.5°C/+3.3% for RCP6.0 and +4.1°C/+4.6% for RCP8.5, respectively. The climate response on RCP 2.6 scenario meets the UN Copenhagen Accord to limit global warming within two degrees at the end of 21st century, the mitigation effect is about 3°C between RCP2.6 and RCP8.5. The projected precipitation changes over the 21st century are expected to increase in tropical regions and at high latitudes, and decrease in subtropical regions associated with projected poleward expansions of the Hadley cell. Total soil moisture change is projected to decrease in northern hemisphere high latitudes and increase in central Africa and Asia whereas near-surface soil moisture tends to decrease in most areas according to the warming and evaporation increase. The trend and magnitude of future climate extremes are also projected to increase in proportion to radiative forcing of RCPs. For RCP 8.5, at the end of the summer season the Arctic is projected to be free of sea ice.  相似文献   

13.
We assess economic costs of heat-induced reductions in worker productivity at global scale under RCP2.6 and RCP8.5. Losses in worker productivity are calculated by using an empirically estimated epidemiological exposure-response function, and the associated economic costs are assessed by using a dynamic multi-region, multi-sector computable general equilibrium model. Autonomous mechanisation of outdoor work in agriculture and construction is implemented in the model. We find that under RCP8.5 by 2100, heat-induced reductions in worker productivity result in an average decline of 1.4% in global gross domestic product (GDP) relative to the reference scenario with no climate change. This is approximately 0.4 percentage points less than when no autonomous mechanisation is assumed. For comparison, measuring the economic costs using occupational health and safety recommendations leads to a 2.4% reduction in global GDP, which is substantially larger than when the epidemiological exposure-response function is used. Countries of Africa, South-East Asia, and South Asia are the worst affected by heat stress. However, economic costs could be substantially alleviated if a 2°C global warming target is achieved. Under RCP2.6, the average reduction in global GDP is only 0.5%. A large fraction of global mitigation costs of achieving the 2°C global warming target could be offset by the avoided adverse impacts of heat stress on worker productivity at higher warming levels.  相似文献   

14.
Climate change hotspots in the CMIP5 global climate model ensemble   总被引:3,自引:1,他引:2  
We use a statistical metric of multi-dimensional climate change to quantify the emergence of global climate change hotspots in the CMIP5 climate model ensemble. Our hotspot metric extends previous work through the inclusion of extreme seasonal temperature and precipitation, which exert critical influence on climate change impacts. The results identify areas of the Amazon, the Sahel and tropical West Africa, Indonesia, and the Tibetan Plateau as persistent regional climate change hotspots throughout the 21st century of the RCP8.5 and RCP4.5 forcing pathways. In addition, areas of southern Africa, the Mediterranean, the Arctic, and Central America/western North America also emerge as prominent regional climate change hotspots in response to intermediate and high levels of forcing. Comparisons of different periods of the two forcing pathways suggest that the pattern of aggregate change is fairly robust to the level of global warming below approximately 2 °C of global warming (relative to the late-20th-century baseline), but not at the higher levels of global warming that occur in the late-21st-century period of the RCP8.5 pathway, with areas of southern Africa, the Mediterranean, and the Arctic exhibiting particular intensification of relative aggregate climate change in response to high levels of forcing. Although specific impacts will clearly be shaped by the interaction of climate change with human and biological vulnerabilities, our identification of climate change hotspots can help to inform mitigation and adaptation decisions by quantifying the rate, magnitude and causes of the aggregate climate response in different parts of the world.  相似文献   

15.
工业革命以来,大气中温室气体不断增加,驱动了全球变暖。IPCC第五次评估报告(AR5)指出,人类排放的温室气体导致的地球系统能量增加中90%以上都被海洋吸收,使得海洋增暖,海洋热含量增加。IPCC最新发布的《气候变化中的海洋和冰冻圈特别报告》(SROCC)发现:自1970年以来,几乎确定海洋上层2000 m在持续增暖。1993—2017年间的增暖速率至少为1969—1993年的2倍,体现出显著的变暖增强趋势。此外,在20世纪90年代以后,2000 m以下的深海也已观测到了变暖信号,尤其是在南大洋(30°S以南)。在1970—2017年间,南大洋上层2000 m储存了全球海洋约35%~43%的热量,在2005—2017年期间增加到45%~62%。基于耦合气候模型预估,几乎可确定海洋将在21世纪持续增暖,2018—2100年间海洋热含量上升幅度可能是1970—2017年间的5~7倍(RCP8.5情景)或2~4倍(RCP2.6情景)。变暖导致的热膨胀效应贡献了1993年以来全球海平面上升的约43%。  相似文献   

16.
2019年9月,IPCC正式发布《气候变化中的海洋和冰冻圈特别报告》(SROCC),这是IPCC首次以高山地区与极区冰冻圈和海洋为主题的评估报告。报告全面评估气候变化背景下海洋和冰冻圈变化及其广泛影响与风险,其核心结论包括:气候系统变暖背景下高山地区和极区的冰冻圈普遍退缩,未来冰冻圈将继续消融,高山地区和极区将面临更高的灾害风险;20世纪70年代以来全球海洋持续增暖,未来海洋将继续变暖、加速酸化,影响海洋生物多样性并危及海洋生态系统服务功能和人类社会;近几十年全球平均海平面加速上升,未来数百年海平面仍将持续上升,极端海面事件频发将加剧沿海地区社会-生态系统的灾害风险。报告强调,采取及时、积极、协调和持久的适应与减缓行动,是有效应对海洋和冰冻圈变化,实现气候恢复力发展路径和可持续发展目标的关键所在。本研究认为,需要高度重视海洋和冰冻圈在气候系统变化中的长期和不可逆影响,强化应对气候变化紧迫性认识;高度重视我国冰冻圈和沿海地区面临的气候风险,强化适应能力建设;推动我国牵头的国际大科学计划,强化跨学科、跨领域协同创新,持续提升我国在相关领域的国际影响力和科技支撑能力。  相似文献   

17.
There is considerable research interest in future agro-drought risk assessment, since the increasing severity of climate change-related hazards poses a great threat to global food security. Wheat is the most important staple crop in the world, and China’s wheat production has long been impacted by drought. The frequency, intensity, and duration of droughts may increase due to climate change and stressing the need for robust assessment methods for drought risk, as well as adaptation and mitigation strategies. This paper investigates a method for assessing future wheat drought risk using climate scenarios and a crop model. We illustrate the utility of such an approach by assessing the risk of wheat drought under climate change scenarios in China using the Environmental Policy Integrated Climate model. Results show that the risk level of wheat drought is highest under scenario RCP8.5, followed by RCP4.5, RCP6.0, and RCP2.6, in descending order. If current climate change trends continue, wheat drought risk in China will be at risk levels between RCP6.0 and RCP8.5 by the end of the twenty-first century. The wheat drought risk assessment shows a “low-risk, high-risk, low-risk” spatial pattern starting in the spring wheat-planting regions in northern China and progressing to the winter wheat-planting regions in southern China. Significant differences were observed across regions, but in all RCP scenarios, the relative high-risk zones are the Huang-Huai Winter Wheat Region and the North Winter Wheat Region. In addition, wheat drought risk mitigation and adaptation strategies in China are proposed.  相似文献   

18.
This paper presents a set of energy and resource intensive scenarios based on the concept of Shared Socio-Economic Pathways (SSPs). The scenario family is characterized by rapid and fossil-fueled development with high socio-economic challenges to mitigation and low socio-economic challenges to adaptation (SSP5). A special focus is placed on the SSP5 marker scenario developed by the REMIND-MAgPIE integrated assessment modeling framework. The SSP5 baseline scenarios exhibit very high levels of fossil fuel use, up to a doubling of global food demand, and up to a tripling of energy demand and greenhouse gas emissions over the course of the century, marking the upper end of the scenario literature in several dimensions. These scenarios are currently the only SSP scenarios that result in a radiative forcing pathway as high as the highest Representative Concentration Pathway (RCP8.5). This paper further investigates the direct impact of mitigation policies on the SSP5 energy, land and emissions dynamics confirming high socio-economic challenges to mitigation in SSP5. Nonetheless, mitigation policies reaching climate forcing levels as low as in the lowest Representative Concentration Pathway (RCP2.6) are accessible in SSP5. The SSP5 scenarios presented in this paper aim to provide useful reference points for future climate change, climate impact, adaption and mitigation analysis, and broader questions of sustainable development.  相似文献   

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