21世纪中国极端降水事件预估

摘 要：全球变暖背景下极端降水事件的变化一直受到广泛关注,本文从观测、理论及模拟预估等方面对近十多年来国内外极端降水气候事件的研究作一综述,并给出IPCC第四次评估报告对我国21世纪极端降水指数变化的预估结果。     

IPCC AR6报告解读：极端天气气候事件变化

与IPCC第五次评估报告（AR5）相比,在第六次评估报告（AR6）评估中,观测的极端天气气候事件变化证据,特别是归因于人为影响的证据加强。人类活动造成的气候变化已影响到全球每个区域的许多极端天气气候事件。随着未来全球变暖进一步加剧,预估极端热事件、强降水、农业生态干旱的强度和频次以及强台风（飓风）比例等将增加,越罕见的极端天气气候事件,其发生频率的增长百分比越大。这些结论再次凸显了应对气候变化和极端天气气候事件的必要性和紧迫性。     

石家庄极端冷暖天气气候事件及其与气候变暖

用石家庄市1955～2002年逐日气温资料，取其第95个和第5个百分位值作为确定极端高(低)温日的阈值来检测极端冷暖事件。对发生在2002年的极端冷暖事件进行检测分析证明，上述方法能比较有效地检测极端冷暖事件的发生。计算气温趋势变率表明，石家庄气候有明显的增暖趋势，随气候变暖夏季持续性强高温和破记录高温事件的出现频次增加；寒冷期趋于缩短；极端冷日趋于减少，极端暖日趋于增加。用季极端冷(暖)日数与气温求取相关的方法，分析各季极端冷暖事件与气候变暖的联系发现，气候变暖对冬季极端冷日减少的影响最甚。城市化效应使城市变暖趋势速率高于郊区，尤以最低气温表现明显；暖事件增多、冷事件减少的趋势速率也是城市高于郊区，且冷事件减少速率高于暖事件增多速率。在气候变暖背景下应特别重视冬季冷事件减少给人类带来的潜在影响。     

极端事件对人类系统的影响

在IPCC特别报告《管理极端事件和灾害风险,推进气候变化适应》中,极端天气气候事件对人类系统的影响是最重要的影响评估内容之一,其评估结果为：极端影响可能缘于极端天气气候事件,但也可能并非极端事件的后果。暴露度和脆弱性是灾害风险的重要决定因素;极端和非极端天气气候事件的严重程度和影响在很大程度上取决于对这些事件的脆弱性和暴露度水平;人居模式、城市化和社会经济状况的变化已经影响观测到的脆弱性和暴露度的变化趋势;无论在发达国家还是发展中国家,沿海人居环境均暴露于极端事件,并受其影响,如小岛屿国家和亚洲大三角洲地区;脆弱人口还包括难民、国内流离失所的人和那些生活在边远地区的人;极端事件将极大地影响与气候联系密切的部门,如水、农业、食物安全、健康和旅游业。     

全球气候变化对我国气候安全影响的思考

依据政府间气候变化专门委员会 (IPCC) 第5次评估报告以及国内相关科学研究成果,使用最新的观测资料凝练了对全球气候变化的有关认识;从极端天气气候事件和气候承载力角度,分析了气候变化给我国带来的气候风险。研究发现:1961—2015年我国平均高温日数增加了28.4%,暴雨日数增加了8.2%。21世纪以来,登陆我国热带气旋的强度明显增加。在全球气候变暖的背景下,我国气候承载力将发生明显变化,未来面临的气候风险将加大。因此,保障我国气候安全,需要科学认识气候,提高气候风险意识; 主动适应气候,提高应对极端事件能力;努力保护气候,减缓气候变化的影响。     

写在IPCC关于极端气候事件评估特别报告发表之际

极端天气气候事件对社会经济与人类活动有明显影响,因此政策制定者和公众都很关心极端气候事件的变化。政府间气候变化专门委员会(IPCC)发表的4次评估报告都非常重视评估这方面的研究,自2007年第四次评估报告发表以来,对极端气候事件     

内蒙古地区2007年度气候异常诊断分析

IPCC第四次评估报告指出,全球气候正经历一次以变暖为主要特征的显著变化．位于中高纬度的内蒙古地区为响应最为积极区域之一。内蒙古地区处于东南季风影响的边缘地区．气候要素的年际间变化较大．易发生某些异常突变和出现极值,成为极端天气气候事件出现频率较高地区之一。通过对2007年气象要素的时、空变化分析,探讨在全球和中国气候变暖的背景下,内蒙古自治区气候异常特征．旨在为了解内蒙古地区气候变化区域响应提供依据。     

极端天气与气候事件受到全球变暖影响吗?

<正>极端天气与气候事件对社会与经济和公众生活与生命的影响很大,因此受到公众和政策制定者的极犬关注。近些年的热点问题是:在全球变暖的背景下,极端天气与气候事件是否会受到影响?要回答这个问题,首先需要了解近些年使用的耦合模式比较计划第五阶段(CMIP5)气候模式对极端天气与气候事件的模拟效果,其次是利用CMIP5气候模式评估观洲到的极端天气与气候事件的变化是否是由全球变暖造成的,最后是利用CMIP5气候模式考     

自然气候变异与人为气候变化对径流影响研究进展

 在回顾IPCC于1990-2007年4次关于气候变化对径流影响的评估报告进展的基础上,将第一次与第二次评估报告归纳为第一代--以气候均值变化对径流影响及其适应为主要特征;第三次与第四次评估报告为第二代--突出人为气候变化与自然气候变异对径流影响及其适应问题,分析了常规的气候变化对水文水资源影响评估方法的发展过程及存在的问题。研究结果反映了年代际时间尺度的自然气候变异的影响,而未能考虑与极端事件发生频次和强度变化密切相联的日、季和年际尺度的气候变异的影响,从而低估了气候变暖对洪水、干旱以及农业灌溉需水的负面作用。在介绍国内外研究的基础上,为第五次IPCC评估报告提出了加强交叉学科综合研究的建议。     

IPCC SREX报告中来自专门机构的引文分析

IPCC于2012年发布了《管理极端事件和灾害风险推进气候变化适应特别报告》（简称SREX,图1）。该报告通过IPCC第五次评估报告第一、二工作组的通力合作,第一次将气候科学和社会经济科学相结合,综合评估了气候变化背景下极端灾害的情况及灾害风险管理和适应措施的进展,为各国科学应对气候变化、有效降低灾害风险提供了重要的参考信息。     

京津冀城市群气候变化及影响适应研究综述

本文对2000年以来京津冀城市群气候变化及影响适应的研究成果进行了综述。研究表明：20世纪60年代以来,京津冀城市群年平均气温和极端高温指数显著升高,年降水量波动减少,到21世纪10年代,极端强降水指数降低。京津冀气候变化是全球变暖和城市化共同作用的结果,城市化加速了京津冀变暖趋势,增加了极端高温和极端强降水的频率和强度,气候风险高。未来京津冀城市群协同发展,面临高温热浪、强降水、水资源短缺和海平面上升等风险将更严峻,气候变化适应是京津冀城市群可持续发展面临的紧迫问题,适应策略等方面研究已取得了明显进展,但适用性和针对性还存在不足。本文提出了未来研究展望：深入研究城市化对气候变化的反馈,发展全球气候变化和城市化共同作用下的气候风险精细化预估技术,系统研究气候变化对城市的影响和不同行业的脆弱性,加强温室气体监测评估技术研究,加强适应气候变化的策略、路径和技术研究。     

气候变化国家评估报告(Ⅰ):中国气候变化的历史和未来趋势

The climate change in China shows a considerable similarity to the global change, though there still exist some significant differences between them. In the context of the global warming, the annual mean surface air temperature in the country as a whole has significantly increased for the past 50 years and 100 years, with the range of temperature increase slightly greater than that in the globe. The change in precipitation trends for the last 50 and 100 years was not significant, but since 1956 it has assumed a weak increasing trend. The frequency and intensity of main extreme weather and climate events have also undergone a significant change. The researches show that the atmospheric CO2 concentration in China has continuously increased and the sum of positive radiative forcings produced by greenhouse gases is probably responsible for the country-wide climate warming for the past 100 years, especially for the past 50 years. The projections of climate change for the 21st century using global and regional climate models indicate that, in the future 20-100 years, the surface air temperature will continue to increase and the annual precipitation also has an increasing trend for most parts of the country.     

Recent Progress in Studies of Climate Change in China

An overview of basic research on climate change in recent years in China is presented. In the past 100 years in China, average annual mean surface air temperature (SAT) has increased at a rate ranging from 0.03℃ (10 yr)-1 to 0.12℃ (10 yr)-1 . This warming is more evident in northern China and is more significant in winter and spring. In the past 50 years in China, at least 27% of the average annual warming has been caused by urbanization. Overall, no significant trends have been detected in annual and/or summer precipitation in China on a whole for the past 100 years or 50 years. Both increases and decreases in frequencies of major extreme climate events have been observed for the past 50 years. The frequencies of extreme temperature events have generally displayed a consistent pattern of change across the country, while the frequencies of extreme precipitation events have shown only regionally and seasonally significant trends. The frequency of tropical cyclone landfall decreased slightly, but the frequency of sand/dust storms decreased significantly. Proxy records indicate that the annual mean SAT in the past a few decades is the highest in the past 400-500 years in China, but it may not have exceeded the highest level of the Medieval Warm Period (1000-1300 AD). Proxy records also indicate that droughts and floods in eastern China have been characterized by continuously abnormal rainfall periods, with the frequencies of extreme droughts and floods in the 20th century most likely being near the average levels of the past 2000 years. The attribution studies suggest that increasing greenhouse gas (GHG) concentrations in the atmosphere are likely to be a main factor for the observed surface warming nationwide. The Yangtze River and Huaihe River basins underwent a cooling trend in summer over the past 50 years, which might have been caused by increased aerosol concentrations and cloud cover. However, natural climate variability might have been a main driver for the mean and extreme precipitation variations observed over the past century. Climate models generally perform well in simulating the variations of annual mean SAT in China. They have also been used to project future changes in SAT under varied GHG emission scenarios. Large uncertainties have remained in these model-based projections, however, especially for the projected trends of regional precipitation and extreme climate events.     

Quantifying Changes in Extreme Weather Events in Response to Warmer Global Temperature

Global warming is expected to affect both the frequency and severity of extreme weather events, though projections of the response of these events to climate warming remain highly uncertain. The range of changes reported in the climate modelling literature is very large, sometimes leading to contradictory results for a given extreme weather event. Much of this uncertainty stems from the incomplete understanding of the physics of extreme weather processes, the lack of representation of mesoscale processes in coarse-resolution climate models, and the effect of natural climate variability at multi-decadal time scales. However, some of the spread in results originates simply from the variety of scenarios for future climate change used to drive climate model simulations, which hampers the ability to make generalizations about predicted changes in extreme weather events. In this study, we present a meta-analysis of the literature on projected future extreme weather events in order to quantify expected changes in weather extremes as a function of a common metric of global mean temperature increases. We find that many extreme weather events are likely to be significantly affected by global warming. In particular, our analysis indicates that the overall frequency of global tropical cyclones could decrease with global warming but that the intensity of these storms, as well as the frequency of the most intense cyclones could increase, particularly in the northwestern Pacific basin. We also found increases in the intensity of South Asian monsoonal rainfall, the frequency of global heavy precipitation events, the number of North American severe thunderstorm days, North American drought conditions, and European heatwaves, with rising global mean temperatures. In addition, the periodicity of the El Niño–Southern Oscillation may decrease, which could, in itself, influence extreme weather frequency in many areas of the climate system.     

1.5℃增暖对全球和区域影响的研究进展

《巴黎协定》明确提出将全球平均升温控制在相对于工业化前水平2℃以内,并努力将其控制在1.5℃以内,以降低气候变化的风险与影响。随后,《联合国气候变化框架公约》（UNFCCC）邀请IPCC筹备关于1.5℃增暖影响及温室气体排放途径的特别报告,为UNFCCC谈判提供科学依据。通过回顾近期发表的一些成果发现,在1.5℃到2℃的不同升温条件下,很多极端天气事件发生的概率将增加。2℃条件下一些易受威胁的系统,如生态系统和农业系统,将承受全球变暖带来的严重后果;海平面明显上升,珊瑚礁锐减,季风降水减弱等影响将进一步加强。同时,不同地区对全球不同程度增暖的响应也存在很大差异。总的说来,相较于2℃增暖而言,将增暖控制在1.5℃以内能进一步减小气候变化影响的风险。然而,要把全球增暖控制在1.5℃内具有极大的挑战性,并且目前对1.5℃增暖的影响认识仍然十分不足。定量分析2℃和1.5℃增暖对不同区域自然和人类系统造成的影响差异,需要更高分辨率的模式以及更多针对2℃和1.5℃增暖影响而设计的专门试验支持。     

气候变化国家评估报告（Ⅰ）：中国气候变化的历史和未来趋势

 中国的气候变化与全球变化有相当的一致性，但也存在明显差别。在全球变暖背景下，近100 a来中国年平均地表气温明显增加，升温幅度比同期全球平均值略高。近100 a和近50 a的降水量变化趋势不明显，但1956年以来出现了微弱增加的趋势。近50 a来中国主要极端天气气候事件的频率和强度也出现了明显的变化。研究表明，中国的CO2年排放量呈不断增加趋势，温室气体正辐射强迫的总和是造成气候变暖的主要原因。对21世纪气候变化趋势做出的预测表明：未来20～100 a，中国地表气温增加明显，降水量也呈增加趋势。     

气候变暖背景下降水持续性与相态变化的研究综述

持续性降水和固态降水（或近地面气温为0℃左右的降水）都能导致洪涝和低温雨雪冰冻等灾害性的极端事件,对人民群众生命和财产安全以及社会经济发展也会造成严重危害。目前中外围绕降水量、极端降水事件变化等已开展了大量研究,但在降水持续性和相态变化的特征及其影响机理方面的研究仍显不足。因此,围绕降水持续性和相态变化的相关研究,对近20余年来取得的一些重要研究进展进行回顾。研究指出,在气候变暖背景下降水持续性和相态变化的特征在全球范围内表现出了区域上的不一致性。有关降水持续性变化方面,中国南方地区持续性降水过程及其产生的降水量呈现增多趋势,但北方地区呈现减少的趋势,而西南地区长持续性降水呈下降趋势。至于降水相态变化方面,中国南方地区持续性雨雪冰冻事件在气候变暖背景下总体呈减少趋势。这些变化除了与气候变暖有关外,可能还与大气遥相关模态、低频振荡及ENSO事件等引起的大气环流异常有关。今后应该更多开展气候变暖背景下降水持续性和相态变化的特征、可能机理以及其与气候变暖的可能联系方面的研究,以期通过相关研究深入理解中国降水持续性与相态变化的规律、成因及其与旱涝、低温雨雪灾害等的联系,进一步加深对气候变暖背景下中国天气、气候的影响及其机理的认识。      

Detection, Causes and Projection of Climate Change over China： An Overview of Recent Progress

This article summarizes the main results and findings of studies conducted by Chinese scientists in the past five years.It is shown that observed climate change in China bears a strong similarity with the global average.The country-averaged annual mean surface air temperature has increased by 1.1℃over the past 50 years and 0.5-0.8℃over the past 100 years,slightly higher than the global temperature increase for the same periods.Northern China and winter have experienced the greatest increases in surface air temperature.Although no significant trend has been found in country-averaged annual precipitation, interdecadal variability and obvious trends on regional scales are detectable,with northwestern China and the mid and lower Yangtze River basin having undergone an obvious increase,and North China a severe drought.Some analyses show that frequency and magnitude of extreme weather and climate events have also undergone significant changes in the past 50 years or so. Studies of the causes of regional climate change through the use of climate models and consideration of various forcings,show that the warming of the last 50 years could possibly be attributed to an increased atmospheric concentration of greenhouse gases,while the temperature change of the first half of the 20th century may be due to solar activity,volcanic eruptions and sea surface temperature change.A significant decline in sunshine duration and solar radiation at the surface in eastern China has been attributed to the increased emission of pollutants. Projections of future climate by models of the NCC(National Climate Center,China Meteorological Administration)and the IAP(Institute of Atmospheric Physics,Chinese Academy of Sciences),as well as 40 models developed overseas,indicate a potential significant warming in China in the 21st century,with the largest warming set to occur in winter months and in northern China.Under varied emission scenarios,the country-averaged annual mean temperature is projected to increase by 1.5-2.1℃by 2020,2.3-3.3℃by 2050, and by 3.9-6.0℃by 2100,in comparison to the 30-year average of 1961 1990.Most models project a 10% 12% increase in annual precipitation in China by 2100,with the trend being particularly evident in Northeast and Northwest China,but with parts of central China probably undergoing a drying trend.Large uncertainty exists in the projection of precipitation,and further studies are needed.Furthermore,anthropogenic climate change will probably lead to a weaker winter monsoon and a stronger summer monsoon in eastern Asia.