Changes in mean and extreme climates over China with a 2°C global warming

Based on a 153-year (1948-2100) transient simulation of East Asian climate performed by a high resolution regional climate model (RegCM3) under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario, the potential future changes in mean and extreme climates over China in association with a global warming of 2℃ with respect to pre-industrial times are assessed in this study. Results show that annual temperature rises over the whole of China, with a greater magnitude of around 0.6℃ compared to the global mean increase, at the time of a 2℃ global warming. Large-scale surface warming gets stronger towards the high latitudes and on the Qinghai-Tibetan Plateau, while it is similar in magnitude but somewhat different in spatial pattern between seasons. Annual precipitation increases by 5.2%, and seasonal precipitation increases by 4.2%-8.5% with respect to the 1986-2005 climatology. At the large scale, apart from in boreal winter when precipitation increases in northern China but decreases in southern China, annual and seasonal precipitation increases in western and southeastern China but decreases over the rest of the country. Nationwide extreme warm (cold) temperature events increase (decrease). With respect to the 1986-2005 climatology, the country-averaged annual extreme precipitation events R5d, SDII, R95T, and R10 increase by 5.1 mm, 0.28 mm d -1 , 6.6%, and 0.4 d respectively, and CDD decreases by 0.5 d. There is a large spatial variability in R10 and CDD changes.     

Urbanization and heterogeneous surface warming in eastern China

With the homogeneity-adjusted surface air temperature (SAT) data at 312 stations in eastern China for 1979-2008 and the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) nighttime light data, the spatial heterogeneities of the SAT trends on different scales are detected with a spatial filtering (i.e. moving spatial anomaly) method, and the impact of urbanization in eastern China on surface warming is analyzed. Results show that the urbanization can induce a remarkable summer warming in Yangtze River Delta (YRD) city cluster region and a winter warming in Beijing-Tianjin-Hebei (BTH) city cluster region. The YRD warming in summer primarily results from the significant increasing of maximum temperature, with an estimated urban warming rate at 0.132-0.250℃ per decade, accounting for 36%-68% of the total regional warming. The BTH warming in winter is primarily due to the remarkable increasing of minimum temperature, with an estimated urban warming rate at 0.102-0.214℃ per decade, accounting for 12%-24% of the total regional warming. The temporal-spatial differences of urban warming effect may be attributed to the variation of regional climatic background and the change of anthropogenic heat release.     

气候变化对中国农业的影响

 在全球气候变化背景下，中国的气温不断增高，近50年中国年平均地表气温增加了1.1℃，明显高于全球；降水变化趋势不明显，年代际波动较大，也存在明显的地区差别；极端天气气候事件不断增多。未来气候变化情景，预计中国北方增温幅度高于南方，青藏高原增温最明显，年降水量增加显著区域为华北、西北及东北地区，长江中下游沿岸及其以南地区有小幅度增加。气候变暖将使粮食作物水稻、玉米和小麦的生育期缩短，产量下降；有利于棉花生产，能提高北方棉花产量和品质；三熟区面积将扩大约22.4%，一熟区面积约缩小23.1%，作物种植结构和作物品种的布局将发生变化；主要农作物病虫害呈加重趋势；对温带和寒带的家畜生长是有利的，对热带和亚热带家畜和牧草生长不利；中国四大海区主要经济鱼种的产量和渔获量有不同程度的降低；气候变暖将使中国各类自然植被发生明显北移，土地荒漠化危害范围加大，土壤肥力下降，并增加农业灌溉的需水量，农业水资源供需矛盾加剧。中国农业应对气候变化包括减缓和适应两个方面，应减缓和适应并重。     

Uncertainty in crossing time of 2 °C warming threshold over China

The 2 °C warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature (SAT) change over China will reach 2 °C relative to the pre-industrial era. To understand the uncertainties, we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Representative Concentration Pathways (RCP4.5 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5. The 2 °C threshold-crossing time (TCT) of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a ±1σ range of intermodel SAT change, the upper and lower bounds of the 2 °C TCT could differ by about 25 years or even more. Uncertainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensitivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 °C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a climate more sensitive to CO₂ forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region, and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radiation, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT.     

1951—2014年淮河流域典型等值线变化特征

利用1951—2014年淮河流域29个站点月平均气温和月降水量数据,运用线性倾向估计、累积距平、Mann-Kendall检验及空间分析等方法,分析了1月均温和年降水量的时空变化特征.结果表明:过去64 a,1月均温呈显著升高趋势,升高速率为0.3℃/10a,1986年以后升温趋势显著,并于1973年发生升温突变;年代际方面,20世纪50年代均温最低,20世纪90年代均温最高.年降水量呈不显著减少趋势,减少速率为5.9 mm/10a;年代际降水量波动幅度不大,其中21世纪00年代平均降水量最高,21世纪10年代平均降水量最少.相较于淮河流域年均温变化,1月均温发生暖化突变时间早于年均温,说明1月均温在响应全球变暖方面更加敏感.过去64 a,1月0℃等温线和800 mm等降水量线与秦岭—淮河一线不重合,其主要原因是全球变暖导致的自然带显著北移.     

How would global-mean temperature change in the 21st century?

The time series of HadCRUT3 global-mean surface air temperature (GSAT) anomaly, Pacific decadal oscillation (PDO) index, and the equatorial Pacific sea surface temperature (SST) were utilized, and their long-term trends and multiple time-scale periodic oscillations were explored in this study. A long-term trend with a warming rate about 0.44°C /century during 1850–2008, two cool floors occurred respectively around 1910 and during 1950–1970, and three warm flats happened in the 1870s, 1940s and since the year 1998 were found in the GSAT. In this duration, the variability of GSAT can be well reconstructed by the quasi-21-year, the quasi-65-year, and century-scale oscillations. The recent decadal warm flat is caused by their positive phase overlapping from these three oscillations. The maximum rising temperature reached 0.26°C was simulated in 2004 by the three oscillations. The quasi-21-year and the quasi-65-year oscillations were possibly caused by solar radiation and internal variability of the ocean-atmosphere system. Therefore, an outlook of GSAT for the 21st century was made based on the long-term trend and these three oscillations. It was expected that a cool floor and a warm flat of the GSAT would appear in the 2030s and 2060s, respectively. However, the highest warming range is predicted about 0.6°C, it is less than the threshold 2°C and IPCC projection.     

河南大别山北坡商城金刚台的植被

<正> 一、自然概况: 商城县位于河南东南部,金刚台山区又位于商城县东南隅,东南与安徽省金寨县接圵,西北及东北与我省平川相接,是豫、皖二省的界岭,岭内朝阳洞曾是鄂、豫、皖革命根据地指挥部所在地之一。金刚台地处北纬31°42′—31°45′,东径约113°38′—115°29′,属淮河流域水系,是大别山主要山峰之一,其主脉走向由西南向东北。金刚台海拔1584米,是本     

我国极端温度事件的定义和趋势分析

 利用1961-2005年45 a中国日平均温度的站点资料和累积频率的统计方法,确定了以90%（10%）累积频率为标准的日、旬、月和季四种不同时间尺度的极端高（低）温事件的阈值。分析表明,日尺度阈值（简称“日阈值”）用于检测极端高（低）温事件最为合理。但在日阈值的季节变化中包含系统性的天气扰动,因此需对其进行低通滤波,滤去8日以下的波动,最终可得到较为合理的检测极端温度事件的日阈值。对用日阈值检测出的全国极端温度事件,定义频数（日平均温度等于或超过高阈值的次数）和平均强度（极端温度事件的日平均温度总和与频数的比值）两个参数进行分析,发现频数的线性趋势表现为：高温事件（大于等于高阈值）中,内蒙古和新疆北部均为大趋势区,而西南地区为小趋势区,低温事件（小于等于低阈值）则相反,趋势显著的地区为高温事件中的东北、华北和青藏高原一带。平均强度的线性趋势表现为：高温事件中,我国东北地区为负趋势的大值区,云南西北部和海南省大部分地区为正趋势的大值区。低温事件则相反,趋势显著区则为高、低温事件中25°N的以南地区。     

Simulation of historical and projected climate change in arid and semiarid areas by CMIP5 models

Based on Climatic Research Unit Time Series3.1 temperature and Global Precipitation Climatology Center full data reanalysis version 6 precipitation data,the abilities of climate models from the fifth phase of the Coupled Model Intercomparison Project to simulate climate changes over arid and semiarid areas were assessed.Simulations of future climate changes under different representative concentration pathways(RCPs)were also examined.The key findings were that most of the models are able to capture the dominant features of the spatiotemporal changes in temperature,especially the geographic distribution,during the past 60 years,both globally as well as over arid and semiarid areas.In addition,the models can reproduce the observed warming trends,but with magnitudes generally less than the observations of around0.1–0.3°C/50a.Compared to temperature,the models perform worse in simulating the annual evolution of observed precipitation,underestimating both the variability and tendency,and there is a huge spread among the models in terms of their simulated precipitation results.The multimodel ensemble mean is overall superior to any individual model in reproducing the observed climate changes.In terms of future climate change,an ongoing warming projected by the multi-model ensemble over arid and semiarid areas can clearly be seen under different RCPs,especially under the high emissions scenario(RCP8.5),which is twice that of the moderate scenario(RCP4.5).Unlike the increasing temperature,precipitation changes vary across areas and are more significant under high-emission RCPs,with more precipitation over wet areas but less precipitation over dry areas.In particular,northern China is projected to be one of the typical areas experiencing significantly increased temperature and precipitation in the future.     

Sea surface temperature record from the north of the East China Sea since late Holocene

Using the alkenone paleotemperature index U37^k, a high-resolution sea surface temperature （SST） record since 3600 a BP was reconstructed from the mud area in the north of the East China Sea. Combining with the grain size distribution curve of sensitive grain size group, which may reflect the East Asia Winter Monsoon activity, the palaeoenvironmental evolution cycle throughout the late Holocene in the area was obtained. The marine environment evolution during the last 3600 years displays a five-stage trend. （1） Temperature descending period from 0.85 cal. ka BP to present. The maximum temperature decrease amplitude is 2℃. The winter monsoon intensified and ＇Little Ice Age＇ were recorded in this period. （2） Warming period from 1.90 to 0.85 cal. ka BP. The mean temperature increase amplitude is 0.8℃. The Sui-Tang warming period was recorded at about 0.85--1.35 cal. ka BP and a prominent cooling event was recorded at 1.4 cal. ka BP in this period. （3） Temperature descending period from 2.55 to 1.90 cal. ka BP. Temperature cooling amplitude is 0.9℃. This period is coincident with an integrated temperature circle recorded in the Antarctic ice core, with the temperature changes from a slow cooling stage to a rapid warming stage. （4） Temperature comparatively stable with a little ascending period from 3.2 to 2.55 cal. ka BP. Temperature warming amplitude is 0.3℃. This period is coincident with the temperature fluctuant ascending period recorded in Antarctic ice core. （5） Temperature comparatively stable with little descending period from 3.6 to 3.2 cal. ka BP. This period corresponds with the temperature fluctuant cooling period recorded in Antarctic ice core. Basically, those five periods were coincident with the Antarctic ice core record. During the global cooling stage, the SST change in the continental shelf sea can be adjusted simultaneously.