Why the increase in small lakes on Earth is bad news

The number of small lakes in the world has exploded over the past 35 years, according to a study by the universities of Copenhagen (Denmark) and Shenzhen (China) published in

on October 1 and relayed by the 

.

Over the period, their area increased by 46,000 km², the equivalent of Denmark.

However, this transformation increases the quantities of greenhouse gases released into the atmosphere.

Greenhouse gas plants

According to this team of researchers, water bodies of less than 1 km² produce large quantities of CO2, methane, or even nitrous oxide due to the large quantity of bacteria and fungi that are there.

By way of comparison, while small lakes represent only 15% of the total surface area of ​​lakes, they are responsible for 25% of CO2 emissions and 37% of methane emissions from lakes.

The development of small lakes would thus be at the origin of 45% and 59% of the increase in CO2 and methane emissions from lakes between 1984 and 2019. “These lakes act like greenhouse gas factories”, summarizes the study.

A vicious circle

But why is the number of small lakes constantly increasing?

According to the researchers, this increase is primarily linked to the intensive creation of artificial lakes by man.

But it is also explained by the melting of the permafrost which causes the formation of many small lakes in the layers of ice of the northern hemisphere.

This phenomenon therefore constitutes one of the many vicious circles of global warming: the more there are small lakes, the more the ice melts and the more there are small lakes... At the same time, due to drought and human consumption and water agriculture, many lakes have dried up all over the world.

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