Clouds double El Nino amplitude

The influence of clouds on the atmospheric circulation accounts for more than half of the strength of El Nino and La Nina events, suggests a study published online in Nature Geoscience this week. The findings indicate that incorporating changes in cloud dynamics into climate models may improve our understanding of the response of El Nino/Southern Oscillation (ENSO) to climate change.

ENSO is the most significant source of weather variability on timescales of three to seven years. However, the relative importance of atmospheric and oceanic processes, and the interactions between the two, is the subject of debate.

Thorsten Mauritsen and colleagues compared climate model simulations that accounted for the interactions between clouds and atmospheric circulation with climate model simulations that did not account for these interactions. They find that the variability in sea surface temperatures associated with ENSO is at least twice as strong in the simulations that fully account for the interactions between clouds and atmospheric circulation.