Small lakes continue to grow all over the planet, creating a serious problem!

A new study shows that the number of small lakes on Earth has increased dramatically over the past four decades, which is alarming given the amount of greenhouse gases emitted by freshwater bodies.

The researchers say that between 1984 and 2019, the surface of the world’s lakes increased by more than 46,000 square kilometers (17,761 square miles). This is slightly larger than Denmark area.

Carbon dioxide, methane, nitrous oxide and other gases are constantly emitted from the lakes, caused by bacteria and fungi that feed on dead plants and animals washed down to the bottom of the lake.

Taken together, the spread of these lakes equates to an annual increase in carbon dioxide emissions of around 4.8 teragrams (or trillion grams) of CO2, and for international comparison, this is equal to the increase in CO2 emissions of the whole of the UK in 2012.

Terrestrial ecologist Jing Tang from the University of Copenhagen in Denmark says: “In recent decades, lakes have experienced large and rapid changes that have affected greenhouse gas accounting as well as ecosystems and access to water resources. Among other things, our new knowledge about size and dynamics lakes allow for a better calculation of potential carbon emissions.”

The researchers used a combination of satellite imagery and deep learning algorithms to estimate lake coverage. There are 3.4 million lakes in total.

The team says that small lakes (less than 1 square kilometer or 0.39 square miles) are very important for calculating greenhouse gases because they produce a large amount of emissions for their size.

These less extensive bodies of water account for only 15% of the lake’s total area, but are responsible for 45% of the increase in carbon dioxide production and 59% of the increase in methane emissions from 1984 to 2019.

“Small lakes emit a disproportionate amount of greenhouse gases because they tend to collect more organic matter, which is then gasified,” says Tang, “and also because they are often shallow. This facilitates the penetration of gases to the surface and upwards. in atmosphere”. At the same time, small lakes are more sensitive to climate and weather changes, as well as to human disturbances. As a result, their volumes and the chemical composition of water fluctuate greatly. So while it’s important to identify and map them, they’re also more demanding. Luckily, we were able to. Who exactly did this?”

The researchers say that more than half of the increase in lake cover over the study period was due to human activities, that is, mainly from newly built reservoirs. The rest is mainly due to the melting of glaciers and the melting of permafrost caused by the warming of our planet.

The researchers hope their data will prove useful for future climate models, as much of the greenhouse gases are likely to come from lake surfaces as the lakes melt and warm further.

Research published in the journal Connection with nature.

Source: Science Alert

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