中文摘要：

相对于工业化革命前期,全球年平均地表气温上升2℃的时间和相应的气候变化受到了广泛关注,特别是包括欧盟成员国在内的许多国家和国际组织已经将避免2℃全球变暖作为温室气体减排的首要目标。为此,本文作者基于16个气候模式在20世纪气候模拟试验和SRESB1、A1B和A2温室气体和气溶胶排放情景下的数值模拟试验结果,采用多模式集合方法预估研究了2℃全球变暖发生的时间、对应的大气中主要温室气体浓度以及中国气候变化情况。根据模式集合平均结果,三种排放情景下2℃全球变暖分别发生在2064年、2046年和2049年,大气二氧化碳当量浓度分别为625ppm、645ppm和669ppm（1ppm=10-6）。对应着2℃全球变暖,中国气候变暖幅度明显更大。从空间分布形势上看,变暖从南向北加强,在青藏高原地区存在一个升温大值区;就整体而言,中国区域平均的年平均地表气温上升2.7～2.9℃,冬季升温幅度（3.1～3.2℃）要较其他季节更大。年平均降水量在华南大部分地区减少0～5%,而在其余地区增加0～20%,中国区域年平均降水增加3.4%～4.4%,各季节增加量在0.5%～6.6%之间。

英文摘要：

Timing and climate change with a 2℃ global warming, with reference to the pre-industrial period, have been paid more attention to worldwide. In particular, many countries, including the member states of the European Union, and international organizations have set the greenhouse-gas emission targets for limiting global warming to 2℃. In this study, two sets of simulations performed with 16 atmospheric-ocean general circulation models, i.e.,the model outputs from the 20th Century Climate in Coupled Models （20C3M） and from the Special Report on Emission Scenarios （SRES） emission scenarios B1, A1B, and A2, are used to analyze the timing, atmospheric concentration of greenhouse gases, and climate change over China with a 2℃ global warming. Based on the multi-model ensemble mean, a 2℃ global warming is expected to occur in 2064, 2046, and 2049, with equivalent atmospheric CO2 concentrations of 625 ppm, 645 ppm, and 669 ppm, under the SRES B1, A1B, and A2, respectively. At that time, warming is stronger overall in China. Where the spatial pattern is concerned, warming is stronger towards the north and on the Qinghai-Tibetan Plateau. At the national scale, annual mean surface air temperature is elevated by 2.7-2.9°C, and the winter temperature is elevated by 3.1-3.2℃, which is the strongest among the seasons. Annual mean precipitation is reduced by 0-5% in most parts of South China, but increased by 0-20% in the rest of the country. Annual （seasonal） mean precipitation is increased on average by 3.4%-4.4% （0.5%-6.6%） over China