According to NASA satellite measurements, Finland's carbon dioxide balance is positive, contrary to the greenhouse gas calculations made by the Natural Resources Institute Finland (Luke).

According to official data and the greenhouse gas inventory published by Statistics Finland and compiled by Luke, at the beginning of 2020 Finland was considered a source of roughly 20 million tonnes of CO₂ emissions. That figure represents the share of emissions that Finland's carbon sinks, such as its forests, were theoretically unable to absorb.

A completely contrasting picture emerges from the atmospheric carbon dioxide concentration measurements taken by the NASA OCO-2 satellite. NASA is the United States' aeronautics and space administration agency, and according to its data Finland's annual greenhouse gas balance was roughly 50 million tonnes on the absorption “side”, not the other way round...

How is such a difference possible?

According to Professor Jouni Pulliainen, a researcher at the Finnish Meteorological Institute, the satellite measures the actual carbon dioxide concentration in the atmosphere. On the basis of the measurement data, it is possible to calculate the absorption and emission sources of the soil. The Luke calculations are based on models adopted in the European Union and the UN – so these calculation principles have been developed politically.

Professor Pulliainen believes that the discrepancy in the results is due, first, to the fact that Luke calculates only the sinks and emissions within the land-use zone, but does not take into account natural bogs and wetlands, which are significant carbon absorbers. Second, the calculations do not fully account for the carbon locked up in timber exported from Finland abroad. The imprecision of the statutory methods used in the calculations when modelling wetland emissions can explain these widely differing results.

Consistency with carbon sequestration measurements in forests

Pulliainen stresses that, on the basis of field measurements carried out by the University of Helsinki and the Meteorological Institute, it can be established that the satellite measurements of carbon sequestration in forests agree with them. In so-called in situ studies, the photosynthesis and respiration of plants and soil organisms are measured right down to cell level. The professor emphasises: “Our field measurements give no indication that carbon sequestration in forests is declining.”

The forest measurements were carried out by the Meteorological Institute and the University of Helsinki at various sites: Juupajoen Hyytiälässä, Pallasjärvellä, Sodankylässä and Värriössä. In an international review, the field measurement results were used to refine the satellite estimates.

Professor Pulliainen stresses that carbon absorption depends very much on the weather. Carbon sequestration is most efficient when the winter is cold, spring begins early, the summer is warm and rainy and the autumn frosts arrive earlier – in that case plants photosynthesise efficiently, while the processes by which they release carbon dioxide are halted for as long as possible over the winter. As the professor points out, the CO₂ calculations do not properly take into account the fluctuations in carbon sequestration over the course of the year.

Even more precise data will be available in 2027

The NASA OCO-2 satellite already provides accurate information on the concentration of carbon dioxide in the atmosphere. From 2027, when the new European CO2M satellite begins operating, even more accurate information will be available on carbon sequestration and on the scale of the human-induced impact. In future, the information provided by this new European satellite could replace the contradictory calculations.

“In the first stage, I can see the information provided by the CO2M satellite being used to verify the Luke calculations,” Professor Pulliainen emphasises. In his view, the timing of the new European Union satellite is very well suited to the situation. Under the current US administration, NASA's capacity to map atmospheric carbon dioxide concentrations has been considerably reduced. The European Union satellite will map the situation worldwide.

“An independent emissions calculation is needed”

In the winter, Metsälehti reported that, according to Sweden's greenhouse gas inventory, Sweden's forests have accumulated tens of millions of tonnes of carbon, whereas Finland's forests, on the basis of the aforementioned Luke calculations, have become a source of emissions. It should be stressed that the NASA satellite mapping results agreed with the carbon calculations carried out by the Swedish University of Agricultural Sciences.

Pulliainen believes that Finland should carry out satellite mapping calculations of the greenhouse gas balance, which would provide an independent and objective comparison with the calculations made by Luke.

“Given the uncertainties associated with the current calculation methodology, and how great an impact the results of carbon calculations can have on the Finnish economy, an independent so-called “second opinion” assessment is needed.”