Research Finds That CO2 Reduces Cloud Cover, Thus Reducing Earth’s Cooling

Stratocumulus clouds as seen from the International Space Station.NASA/Public Domain

Computer simulations reveal that cloud loss contributes significantly to rising global temperatures.

New findings published Monday in the journal Nature Geoscience report that cloud loss caused by high levels of CO2 emissions could exacerbate the effects of global climate change. Currently, clouds cover about two-thirds of the planet and serve the important role of reflecting sunlight back to space.

Researchers at the California Institute of Technology performed computer simulations and revealed that when the concentration of CO2 reached 1,200 parts per million, stratocumulus clouds, the type with the largest cooling effect, disappear entirely. When this “tipping point” was broken in the simulation, the disappearance alone caused an 8 degree Celsius increase, double the increase caused by CO2 emissions alone.

Current levels of fossil fuel burning will cause the atmosphere to reach the tipping point in about a 100 to 150 years, but rising global temperatures lead to fewer clouds, creating a dangerous feedback loop. Experts have only recently confirmed that cloud loss is one of--if not the--largest factors in determining levels of global warming.

“You can fairly confidently say that the model spread in climate sensitivity is basically just a model spread in what clouds are going to do,” said Kate Marvel from the Nasa Goddard Institute for Space Studies in New York City.

The predictions also reveal important facts about the Earth’s past. Prior models of the Paleocene-Eocene Thermal Maximum, an episode of rising global temperatures 56 million years ago, failed to accommodate for cloud loss, leaving experts puzzled. Now, it is clear that clouds heavily influence past and future periods of global warming.

Read the full story at Quanta Magazine.