The thawing permafrost in the northern hemisphere leads to large greenhouse gas emissions. But so far, there have been no precise measurements of how the lakes and rivers formed affect the extent of the emissions. This is a shortcoming in today's climate models.

In a doctoral dissertation soon to be presented at Umeå University, which is based on long-term field studies and accurate measurements in western Siberia, Svetlana Serikova shows that greenhouse gas emissions from watercourses are significantly greater than the researchers have so far expected.

Twice Sweden's emissions

In total, greenhouse gas emissions from the waterways of western Siberia correspond to 100 million tonnes of carbon dioxide equivalent. This can be compared to Sweden's emissions, which is just over 50 million tonnes.

- Previous estimates have been based on coarser measurements and are therefore not entirely easy to compare with. But I would say that emissions are at least twice as large as previously thought, says Svetlana Serikova to TT.

She is a researcher at the Department of Ecology, Environment and Earth Sciences at Umeå University and, together with her colleagues, has spent several years measuring emissions from water surfaces in different parts of western Siberia using box-like measuring instruments.

-It's a fantastic landscape. But the heating is very concrete. You see how new lakes are being formed year on year as the permafrost melts, says Svetlana Serikova.

Both thawed and frozen ground

Measurements have been made along a 1,000 kilometer stretch, with completely frozen areas in the north and thawed areas in the south. The results show that it is mainly from the rivers that the emissions increase when the permafrost thaws. Emissions from the lakes are greatest in areas where the permafrost is still intact. Thus, it seems to involve two different mechanisms.

-The overall picture is that the emissions are greater than we previously thought. But the most important message is that more knowledge is needed. Conditions are affected quickly and we need to know more to be able to make reliable climate models, says Svetlana Serikova.