A study published July 11 in the online edition of Nature may explain why storm tracks, such as the paths of hurricanes and typhoons, may be shifting as a result of a warming climate. The research results also help resolve one of the biggest gaps between predictions made by climate models and datasets and the actual degree and extent of the Greenhouse Effect.
By empirical and independent correction of satellite records measuring changes in clouds and patterns taken by weather satellites from the 1980s to 2000s, a research team found that they "exhibit large-scale patterns of cloud change...that are similar to those produced by model simulations with recent historical external radiative forcing." External radiative forcing is the scientific term for climate warming caused by humans.
Previously undetected changes in clouds
More specifically, the research team found that both the observed and predicted cloud changes over the two-decade period jibe with the movement of mid-latitude storm tracks towards the poles. They also are consistent with the expansion of dry zones in subtropical regions and the increasing height of the highest cloud tops at all latitudes.
As to the primary drivers, the researchers point to rising greenhouse gas emissions and recovery from the cooling effect of volcanic activity.
"The expansion of subtropical dry zones results in less reflection of solar radiation back to space," the researchers wrote. "As cloud tops rise, their greenhouse effect becomes stronger. Both of these cloud changes have a warming effect on climate."
More fundamentally and broadly speaking, the study results, method and techniques employed by the research team are significant in that they indicate the most consistent predictions produced by global climate models are actually taking place in nature.
The study was produced by climate scientists from the University of California (UC) San Diego's Scripps Institution of Oceanography, UC Riverside's Department of Earth Sciences, Lawrence Livermore National Laboratory's Program for Climate Model Diagnosis and Intercomparison, and Colorado State University, Fort Collins's Cooperative Institute in the Atmosphere.
*Image credits: Wunderground; Live Science