The mainstream and long-held view of clouds in relation to climate change is that clouds are acting as a feedback in response to temperature changes caused by human activity. Some sceptics however argue that it is the other way around and that clouds are actually the cause of global warming.

A new study that was published in the peer-reviewed journal Geophysical Research Letters now puts an end to the discussion in favour of the former view, hopes Andrew Dessler, atmospheric sciences Professor of Texas A&M University.

To reach this conclusion Dessler analysed data of El Niño and La Niña cycles obtained between 2000 and 2010.

El NiNò and La Niña

El Niño and La Niña go through 2 to 7 year long cycles and their state strongly influences global weather systems. Clouds however play just a minimal role in initiating these climatic variations as the study shows.

Calculations into energy budget show that the energy trapped by clouds and the lag in energy distribution from the top of the atmosphere to the earth’s surface caused by clouds can account for just a small part of the observed climate variations. In fact the calculations showed that the influence of oceans on the Earth’s climate was 20 times larger than that of cloud cover. This means that increased cloud cover cannot be responsible forthe recent rise in global temperatures.

Amplifying effects

Clouds can however amplify the effects of already rising temperatures thus speeding up global warming. But without another influence, like let’s say human activities, to raise temperatures, clouds do not play this feedback role.

© Jorn van Dooren | www.bitsofscience.org