...Pedro DiNezio of the University of Hawaii and Jessica Tierney of Woods Hole Oceanographic Institution investigated preserved geological clues (called "proxies") of rainfall patterns during a time when the planet went into opposite gear and cooled dramatically in the last ice age. Land clues included charcoal from fires, and evidence of more sand dune activity and desiccated lakes, all indicating drier conditions, and evidence for higher lake levels and more pollen, indicating wetter conditions.
They also looked at records of seafloor sediments containing preserved shells of dead marine organisms; the shells contain higher or lower levels of a heavier isotope of oxygen, depending on the relative salinity of surface waters when the organisms were alive (less salty waters indicate more rainfall over the ocean).
...They then compared this evidence with results from 12 different mathematical climate models that simulate Earth's climate, which incorporate basic laws of physics, chemistry, and fluid dynamics surrounding air-sea-land-ice interactions. ...Their results surprised them: Only one model, developed by the Hadley Centre for Climate Prediction and Research in the England, reproduced the rainfall patterns they found from the geological evidence....
..."The good news is, the Hadley model combined with the geological evidence show a pathway to improve our ability to simulate and predict tropical rainfall in the future," Tierney said....
Rainfall from Cyclone Gonu in 2005, via NASA
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