University at Albany, USA
Title: Desert amplification and Global Warming
Liming Zhou has research interests in land-atmosphere/climate interaction, land-surface remote sensing, remote sensing of vegetation dynamics,land-surface modeling, climate modeling, andapplications of various remote sensed products in weather, climate, and environmental sciences.During the past decade, he has used satellite data, observations and climate models to understand physical processes/mechanisms and interactions of land-human-climate systems, and to improve model capability to predict climate change and assess its impacts and consequence on our climate and environment. Land surface processes related to vegetation dynamics, deforestation, afforestation, urbanization, desertification, and renewable wind energy are his emphases.
Previous research found that the warming rateobserved for the period 1979–2012 increases dramaticallywith decreasing vegetation greenness over land in mid- and low- latitudes, with the strongest warming rate seen overthe driest ecoregions such as the Sahara desert and the ArabianPeninsula, suggesting warming amplification over deserts.Here I analyze the observed and projected surface temperature anomalies over land between50°S-50°N for the period 1950–2099 by large-scale ecoregion and find strongest warming consistentlyand persistently seen over the driest ecoregions duringvarious 30-year periods, pointing to desert amplification in a warming climate (similar to polar amplification). This amplificationenhances linearly with the global mean greenhouse gases (GHGs) radiative forcing. Possible mechanisms for this amplification are explored by analyzing changes in various variablesrelated to atmospheric profiles, surface radiative forcing, landsurface properties, and surface energy and radiation budget. My results show that desert amplification islikely attributable mostly to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surfaceover drier ecoregions as a consequence of a warmer and thus moister atmosphere in response toincreasing GHGs. These results indicate that desert amplification may represent a fundamental patternof global warming associated with water vapor feedbacks over land in low- and mid- latitudes wheresurface warming rates depend inversely on ecosystem dryness. It is possible that desert amplificationmight involve two types of water vapor feedbacks that maximize respectively in the tropical uppertroposphere and near the surface over deserts, with both being very dry and thus extremely sensitive tochanges of water vapor.