White Cloud Distribution Has Shifted over the Last 30 Years

A recent study has found that the distribution of white clouds, which play a major role in temperature regulation planetwide, has shifted over the last three decades. And a group of scientists suspect that climate change may play some part in it.

Researchers found that white clouds moved towards the poles expanding dry tropical areas, which may make global warming even worse. The research team also detected a small rise in cloud tops over the same time period.

Lead author of the study Joel Norris, who is also a climate scientist with the University of California’s Scripps Institution of Oceanography, explained that computer models backed by observational data suggest that as climate change gets worse the storm track will gradually move closer to the poles. Additionally, dry tropical areas situated around 20 and 30 degrees latitude would also expand pole-ward.

Norris added that clouds are now located at higher altitudes in the atmosphere than they were 30 years ago. The researcher explained that the accumulation of greenhouse gases is lowering the temperatures in stratosphere while the troposhere, which is located below gets warmer. As a result, clouds can now rise higher than in previous decades.

The findings were based on satellite imagery taken between 1983 and 2009 and computer simulations. Norris said that those simulations had predicted the shift in white cloud distribution, but it is only now that theoretical data has been confronted with satellite data.

According to the paper, there were changes in cloud amount and reflectivity over the northwestern parts of the tropical Pacific Ocean, Indian Ocean, and northern regions of the Atlantic and Pacific oceans. In these areas cloud reflectivity and amount have dropped since 1983.

Scientists believe that these changes may be “positive feedbacks” linked to global warming, which could spur even higher temperatures.

Norris’s team believes that the recent shift in cloud distribution towards the poles could boost climate change in the future. If clouds move pole-ward less solar radiation is reflected in tropical regions, researchers argued.

Furthermore, the rise of cloud tops could also fuel global warming because the overall column of cloud gets thicker which prevents more heat and radiation from escaping into space. So, more heat is trapped at lower levels which could worsen global warming in unexpected ways.