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To help quantify changes in carbon absorption, ESA’s GlobSnow project produced daily snow cover maps over the whole northern hemisphere from 1979 to 2015 using satellites.  

A team of climate and remote sensing scientists led by the Finnish Meteorological Institute recently analysed the information and found that the start of plant growth in the spring has shifted earlier by an average of eight days over the last 36 years.

By combining this information with ground-based observations of the atmosphere–ecosystem  carbon dioxide exchange from forests in Finland, Sweden, Russia and Canada, the team found that this earlier start to spring growth has increased the forest uptake of  carbon dioxide from the atmosphere by 3.7% per decade. This acts as a brake on the growth of atmospheric carbon dioxide, helping to mitigate the rapid increase of carbon dioxide from man-made emissions.

The scientists also found that the shift in spring recovery is much larger in Eurasian forests, leading to double the increase in carbon uptake compared to North American forests.

“Satellite data played an essential role in providing information on variability in the carbon cycle,” said Prof. Jouni Pulliainen, who led the research team at the Finnish Meteorological Institute.

“By combining satellite- and ground-based information, we were able to turn observations of melting snow into higher-order information on springtime photosynthetic activity and carbon uptake.”

These new results will now be used to improve climate models and help to increase the accuracy in predictions of global warming.

Next year, ESA plans to improve the satellite-based record of global snow cover with the upcoming Snow_cci project of ESA’s Climate Change Initiative.