Water Evaporated from Trees Might Cool Our Planet

A research team Carnegie’s Department of Global Ecology has recently performed a study that proves the impact that evaporation of water from trees and lakes has on the global climate.

The fact that the Earth is getting warmer and warmer each decade is no news for us. This mostly happens as a result of the emissions of carbon dioxide from the burning of coal, oil, and gas, as well as the clearing of forests.

It is well known that creating new urban areas and deforestation can contribute massively to local warming by decreasing local evaporative cooling, but it was not understood whether this decreased evaporation would also contribute to global warming.

According to the findings published in Environmental Research Letters, the water evaporated from vegetation helps cooling down the planet. The effect does not just apply in the local area of evaporation, but spread over the entire atmosphere.

This comes to contradict previous presumptions which stated the fact that evaporation could have a warming effect on global climate, because water vapor acts as a greenhouse gas in the atmosphere.

Also, it was thought it was possible that the energy taken up in evaporating water is released back into the environment when the water vapor condenses and returns to earth, mostly as rain. However, evaporation cannot directly affect the global balance of energy on our planet.

In fact, increased evaporation tends to cause clouds to form low in the atmosphere, which act to reflect the sun’s warming rays back out into space, thus creating the cooling effect.

“This shows us that the evaporation of water from trees and lakes in urban parks, like New York’s Central Park, not only help keep our cities cool, but also helps keep the whole planet cool,” Ken Caldeira, a member of the research team, said in a statement.

“Our research also shows that we need to improve our understanding of how our daily activities can drive changes in both local and global climate. That Steam coming out of your tea-kettle may be helping to cool the Earth, but that cooling influence will be overwhelmed if that water was boiled by burning gas or coal,” he added.