关键词: 气候变化, SPEI, 干旱, 时空变化

Abstract: Drought is an insidious，slow-onset natural hazard that produces a complex web of impacts that ripple through many sectors of economy. As vulnerability to drought increase because of mounting pressure on water and other natural resources，it is clear that the scientific community faces a significant challenge to produce more timely and more comprehensive assessment of impacts. The development of drought projection is facilitated by the general circulation model （GCM）. Based on the monthly data under SRES A1B，A2 and B1 climate scenario （2011-2050） and the baseline （1971-2010） from the third phase of the coupled model intercomparsion projection （CMIP3） multi-model datasets with resolution of 1°×1°，the standardized precipitation evapotranspiration index （SPEI），which is proved to be suited to detecting，monitoring and exploring the consequences of global warming on drought conditions，is used in the drought projection in the North China. The results indicate that the North China faces a drying trend for all scenarios in the next 40 years. The increases in precipitation are offset by increased evaporation. In general，changes under the higher emission scenarios，A2 and A1B are greater，and despite following a reduced emissions pathway relative to the present day，the B1 scenario shows smaller but still substantial increase in drought. Under the future projections，the mild and moderate drought occurs less frequently，while the severe and extreme drought occurs more frequently. Compared with the baseline of 1971-2010，the extreme drought frequency for 36%，48% and 60% of the pixels increase greater than 2 times·（10 a）-1 in 2040s under B1，A1B and A2 climate scenario，respectively. Regionally，the semi-arid regions show large increase most notably for extreme drought frequency，followed by the arid region，semi-humid region and humid region under three climate change scenarios. The spatial extent of extreme drought do not show significant increasing trend in the next 30 years. Compared with the baseline of 1971-2010，the spatial extent of extreme drought increase -0.2~2.1%，-0.87~2.7% and -0.6~2.9% during 2011 to 2040 under A1B，A2 and B1 climate scenario，respectively. However，in 2040s，the spatial extent of extreme drought increases 11.9%，11.4% and 12.1% under A1B，B1 and A2 climate scenario，respectively. The drought intensity shows an increasing trend from 2011 to 2050，especially in the 2040s. These indicated that in the 2040s，the North China will go through a phase of extreme drought increase on frequency，intensity and spatial extent. With the drought indices and GCM model，it is available to offer spatial-temporal variation characteristics of drought under climate change scenario，and these may provide scientific supports for the assessment of the impact of climate change on agriculture and its adaption countermeasures formulation.

Key words: climate change, SPEI, drought, spatial-temporal variation