A new study has shown that the world’s smallest lakes have grown significantly over the past four decades – a worrying development, considering the amount of greenhouse gases that the reservoirs produce.
Between 1984 and 2019, the world’s oceans it increased in size by more than 46,000 kilometers (17,761 square miles), researchers say. This is more than the area in Denmark.
Carbon dioxide, methane, nitrous oxide, and other gases are constantly produced in the sea, due to bacteria and fungi that feed on the bottom of the water, and eat the plants and animals that have fallen to the bottom of the sea.
In total, the expansion of the lake is equivalent to an annual increase in carbon dioxide emissions in the region of 4.8 teragrams (or trillions of grams) of CO.2 – which the continuation of the comparison of the world corresponds to the increase of CO2 it was released across the UK in 2012.
“There have been large and rapid changes in the oceans in recent decades that affect the greenhouse gas account, as well as ecosystems and water availability,” says terrestrial biologist Jing Tang, from the University of Copenhagen in Denmark.
“Among other things, our new knowledge of the size and shape of the oceans helps us better calculate how much carbon they can release.”
The researchers used satellite imagery and deep learning techniques to re-estimate the extent of the ocean. A total of 3.4 million lakes were created.
Small lakes (less than one kilometer or 0.39 square kilometers) are more important for greenhouse gas calculations because they emit more carbon relative to their size, the group says.
These shallow waters cover only 15 percent of the ocean’s surface, yet they are responsible for 45 percent of the increase in carbon dioxide and 59 percent of the increase in methane emissions from 1984 to 2019.
Tang said: “Small oceans produce a lot of carbon dioxide because they often accumulate organic matter that turns into carbon dioxide. “Also, because they are usually shallow. This makes it easier for the air to reach the surface and rise into the atmosphere.”
“At the same time, small lakes are very affected by climate and climate change, as well as human disturbance. As a result, their size and water level are very variable. Therefore, although it is important to identify and map them. it is very difficult. Fortunately, we managed to do that.”
More than half of the rate of sea level rise during the study period is due to human activity, the researchers say – in particular, newly constructed reservoirs. Some are mainly due to the melting of ice and the melting of ice, due to the warming of our planet.
The researchers hope their findings will also help future climate models, with more greenhouse gases likely to come from the oceans as melting and warming continue.
“In addition, these records can be used to better estimate the water quality of the oceans and to better assess the risk of flooding, as well as to better manage the oceans – because the ocean environment also affects biodiversity,” says Tang.
Research has been published in Nature Communications.
