AGU: Geophysical Research Letters

 

Editors' Highlight

Solar and human-induced climate forcing on tropical hydrology

Changes in the hydrologic cycle, including droughts and flooding, are among the most immediate projected consequences of global warming for human society. However, the relationship between climate change and hydrologic change is poorly understood on a global scale. Noting that past research has suggested substantial correlations between tropical meteorology and solar variations over the past 8000 years, Shindell et al. (2006) used a coupled ocean-atmosphere model forced by sustained multidecadal irradiance increases. Their data show that warmer tropical temperatures alter the hydrologic cycle, enhancing precipitation in the tropics while drying subtropical regions. This response mimics patterns seen in a wide variety of paleoclimate proxy records. The authors noted that the shift in climate that they described likely affected past civilizations, including the Maya and ancestral Puebloans who experienced drought coincident with increased irradiance during late medieval times. Because projections of 21st century climate change, driven by increased greenhouse gas concentrations, yield hydrologic changes through similar processes, the authors expect increased subtropical drought as climate warms.

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