Extended Abstract (1012K)9.1
Has the Recent Global Warming Caused Increased Drying over Land?
Aiguo Dai, NCAR, Boulder, CO; and T. Qian and K. E. Trenberth
Most climate models predict increased drying over inland areas due to enhanced evaporation associated with increased surface temperatures. Surface air temperatures over global land areas have increased sharply since the late 1970s. Has this warming caused any drying trends over global land areas? Because of a lack of historical records of soil moisture, here we address this question by analyzing various proxy data, which include the Palmer Drought Severity Index (PDSI) calculated using observed monthly precipitation and temperature, stream-flow records, observed surface relative humidity, and historical simulations using a comprehensive land surface model forced with observed precipitation and other atmospheric forcing. Preliminary results suggest that global very dry (PDSI < -3.0) areas have more than doubled since the 1970s primarily due to the recent surface warming, even though some regions such as the U.S., Argentina, and Ukraine have become wetter because of increased precipitation. In this paper we describe how PDSI results are combined with the other data to explore the potential drying effect associated with the recent global warming.
Supplementary URL: http://www.cgd.ucar.edu/cas/adai/
Session 9, Living With a Limited Water Supply (parallel with Session 8)
Wednesday, 12 January 2005, 8:30 AM-9:30 AM
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