Galactophagist: Should we worry about cloud cover changes?

The effect clouds have on climate has been something of a mystery to atmospheric scientists, with some researchers hoping they would provide a silver lining by acting as a brake on climate change.

A group of researchers from the University of Miami and the Scripps Institute of Oceanography studied cloud data of the northeast Pacific Ocean — both from satellites and from the human eye — over the past 50 years and combined that with climate models. They found that low-level clouds tend to dissipate as the ocean warms — which means a warmer world could well have less cloud cover. "That would create positive feedback, a reinforcing cycle that continues to warm the climate," says Amy Clement, a climate scientist at the University of Miami and the lead author of the Science study.

In research published in Geophysical Research Letters, and highlighted in the May 1 edition of Science Magazine, Adams and Pierce report the first atmospheric simulations of changes in atmospheric ions and particle formation resulting from variations in the sun and cosmic rays. They find that changes in the concentration of particles that affect clouds are 100 times too small to affect the climate.

If the amount of cloud cover reflecting sunlight back to space decreases from, say, a change in oceanic and atmospheric circulation patterns, then more sunlight will be absorbed by the ocean. As a result, there will then be an imbalance between the infrared energy lost and solar energy gained by the Earth. The ocean will warm as a result of this imbalance, causing warmer and more humid air masses to form and flow over the continents, which would then cause the land to warm, too.