How clouds affect global warming, and vice versa

Clouds seem to be amplifying global warming, according to a recent study. Photo: AFP

Global warming may lead to changes in the Earth's cloud cover, which itself may amplify climatic disruption, according to a new study.

Clouds have a significant influence on climate, and vice versa. As the Earth's global temperature increases, the number, density and altitude of cumulus, cirrus, nimbus and other clouds should change.

If, up until now, it has been difficult to predict the magnitude of these changes on global warming, this new study published in the Proceedings of the National Academy of Sciences has now quantified the phenomenon.

According to the researchers, the probability that these changes will worsen global warming is 97.5%.

The explanations are complex. There are two types of clouds: the so-called "low clouds", located at less than two kilometers of altitude and having a cottony appearance, and the "high clouds", located in higher atmospheric layers.

While the former cool the planet, the latter prevent heat from escaping from the atmosphere.

The increase in global warming could come from a double phenomenon. The "umbrella effect" of low clouds is diminished, leading to a decrease in the fraction of land covered by them.

At the same time, the "cover effect" of high clouds may tend to increase, and these clouds will be higher up in the sky. Which spells bad news in the view of the study authors whose work suggests that the higher these clouds are, the greater the greenhouse effect.

According to the research, the combination of these two dynamics would amplify global warming. While the study is not groundbreaking, it does provide evidence for cloud feedback, the main source of uncertainty in climate change.

While the debate is not yet settled, this latest study has certainly moved it forward. According to the experts, a doubling of the concentration of CO2 in the atmosphere can warm the planet by 3.2°C. A temperature with catastrophic consequences for human beings. – AFP Relaxnews

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