中国西北地区气候转型的新认识

近年来,中国西北地区的气候变化问题引起了社会各界的广泛关注,施雅风曾在2002年提出中国西北气候可能会从暖干向暖湿转型,自此学者们对中国西北气候“变暖变湿”现象的关注也逐渐增多,对于近20 a来气候转型的时间、范围和程度有了一些新的认识。基于此,选用1960—2019年逐月气温和降水量资料对中国西北地区气候变化特征进行了再分析。结果表明：（1） 1960—2019年中国西北地区平均气温和降水量均呈上升趋势,增暖趋势显著,增湿趋势较弱。（2） 自1997年后气温和降水量迅速增加,尤其是中国西北地区的东部地区降水量的增加速率超过同时期的西部地区。且研究初步认为,1997年以来中国西北气候的确出现了向暖湿转型的趋势且转型时间较前人预期的更早。（3） 气候转型的范围相较前人研究也有所变化,甘肃陇东地区由未转型区转变为显著转型区,青海东、西部地区由原来轻度转型区转变为显著转型区,而祁连山中西段地区由之前的显著转型区转变为轻度转型区。

New insights into climate transition in northwest China

In recent years, the issue of climate change in northwest China has aroused widespread concern from many walks of life. Shi Yafeng proposed in 2002 that the climate in northwest China may be changing from warm and dry to warm and wet. Since then, scholars have gradually paid more attention to the phenomenon of “warmer and wetter” in the northwest climate. From the beginning of the 21^st century, a trend of increasing temperatures has become more pronounced, and changes in precipitation have diverged from the predictions of previous studies. Against this background, what recent changes have taken place in temperature and precipitation in northwest China? In particular, has the climate undergone a dry-wet transition in the past 20 years due to rising temperatures and increased precipitation? Has the region itself changed in response? This contribution analyzed average temperature and precipitation data for northwest China from 1960 to 2019. From this, temporal and spatial characteristics of climate change were assessed, revealing more about the possible transformation to warm, humid conditions. Such changes are significant to the ecological environment, social and economic development, human production, and life practices in northwest China, and their understanding provides a basis for responding to climate change and disaster prevention or mitigation across northwest China. The study found that: (1) Average temperature and precipitation both showed an upward trend in northwest China from 1960 to 2019, with a significant warming trend and a weaker humidification trend. (2) Since 1997, both temperature and precipitation have risen rapidly, especially in the eastern part of northwest China, where the rate of increase in precipitation has exceeded that of the western part over the same period. Moreover, this research suggests that, since 1997, northwest China has indeed experienced a warm and humid climatic transition; the onset of this transition was earlier than previously recognized. (3) Compared with previous studies, the geographic character of the climate transition has also changed: east Gansu Province has changed from a non-transition area to an area of significant climatic transition; and the eastern and western areas of Qinghai Province have changed from mild transition areas to areas of significant transition.