Simple equations explain the effect of clouds on climate

Scientists have tested how the reflection and absorption of light by clouds affects the Earth’s climate. According to them, everything can be described by a model that relies on a few simple equations.

Clouds in the Earth’s atmosphere. Source: Earth Science and Remote Sensing Unit, NASA Johnson Space Center

How clouds affect the climate

Scientists have conducted a new analysis of the interaction of clouds in the Earth’s atmosphere with heat and light. It has reduced uncertainty about how they will affect climate change on our planet. Scientists have long known that these atmospheric formations can act on it in two opposite ways. 

On the one hand, clouds can reduce global temperatures by reflecting sunlight into space. On the other hand, on the contrary, they can retain heat at the surface of the Earth and thus make the climate hotter. Until now, scientists have not understood the proportions in which these two processes manifest themselves in the Earth’s atmosphere.

In a new study, scientists from the University of Exeter and the Laboratory of Dynamic Meteorology in Paris have created a model that predicts how changes in the surface area of anvil clouds (aka storm clouds) will affect global warming. 

By testing their model based on observations of how clouds affect warming in our time, they confirmed its effectiveness and thereby reduced uncertainty in climate forecasts.

Influence of clouds on global warming

The model shows that changes in the area of anvil clouds have a much weaker effect on global warming than previously thought. However, the brightness of clouds (which is determined by their thickness) remains insufficiently studied, and therefore is one of the biggest obstacles to predicting future global warming.

“Climate change is complex, but sometimes we can answer key questions in a very simple way,” said study lead author Brett McKim.

“In this case, we simplified clouds into basic characteristics: either high or low, their size and the temperature,” explained McKim. “Doing this allowed us to write equations and create a model that could be tested against observed clouds.”

The results obtained more than halve the uncertainty about the effect of the surface area of anvil clouds on warming. This is a big step, potentially equivalent to a difference of several years in time when we expect to reach thresholds such as the 2°C limit set by the Paris Agreement. 

Now scientists need to investigate how warming will affect the brightness of clouds. This will be the next stage of their research.

According to

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