Mapping global lake dynamics reveals the emerging roles of small lakes

Small lakes are big emitters of greenhouse gases

28 February 2023

A stocktake of the world’s lakes reveals that small lakes make an oversized contribution to greenhouse-gas emissions.

Lakes are important ecosystems, but they also emit greenhouse gases due to the breakdown of plant and animal material on their beds.

Human activities and climate warming have been altering lake sizes in recent decades, but this has been hard to quantify since it can be tricky to distinguish lakes from rivers in satellite images.

Now, a team led by researchers from SUSTech in Shenzhen, China, has mapped 3.4 million lakes using satellite imaging and deep learning, and determined how their sizes have changed over the past 40 years.

The results show that global lake area has increased by roughly the area of Denmark and that half of this increase is due to reservoirs.

While lakes smaller than 1 square kilometre make up only 15% of the global lake area, they make a disproportionate contribution to greenhouse gases, accounting for 25% of carbon dioxide and 37% of methane emitted.

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References

1. Nature Communications 13, 5777 (2022). doi: 10.1038/s41467-022-33239-3