The sea surface temperature threshold above which the tropical atmosphere becomes unstable and open to the formation of deep thunderclouds has risen in line with surface ocean warming, suggests a study published online this week in Nature Geoscience.

Nathaniel Johnson and Shang-Ping Xie analysed satellite data recording rainfall and sea surface temperatures in the tropics, and found that sea surface temperatures have risen by 0.1℃ per decade over the past 30 years. They went on to estimate the sea surface temperature threshold for deep convection which affects the regions of cyclone formation, tropical atmospheric temperature and rainfall. This threshold had risen at the same rate, suggesting that the stability of the tropical atmosphere has been unaffected by climate change.