What is a carbon sink?

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With regard to forests, the term "carbon sink" means that a forest stores more carbon dioxide than it releases into the atmosphere. But why is all of Europe so interested in this basic biological phenomenon at the moment?

Carbon dioxide is a vital gas. It is necessary for photosynthesis: plants use sunlight to turn water and carbon dioxide into oxygen and a sugar called glucose. Trees turn glucose into other substances, such as cellulose. Trees take in carbon dioxide from the air and store it as carbon.

Carbon dioxide is created when carbon-containing substances are burned or when they decompose in other ways. Breathing also generates carbon dioxide. According to a popular saying, "Forests are the lungs of the earth". This is actually incorrect, as forests produce oxygen, whereas the lungs generate carbon dioxide. Nevertheless, plants that produce oxygen are vital to life.

As trees grow, they store carbon in their trunks, branches, roots and leaves. Plant litter stores carbon in the soil. Carbon is released back into the air as carbon dioxide when wood and plant litter decompose. When wood is being used, the carbon is stored or released, depending on what is being made from the wood.

A wooden house provides long-term carbon storage, whereas a piece of firewood or a newspaper stores carbon only for a short period of time. Wooden products can be burned to produce energy or recycled. Pulp processes also generate wood-based energy as a by-product.

The Finnish forests are a carbon sink, as their growth stores more carbon than is released through their use and natural drain. Finland's growing forest assets have been helping to reduce the amount of carbon dioxide in the atmosphere for decades.

Why does atmospheric carbon dioxide matter?

Carbon dioxide is a greenhouse gas, meaning that it traps the heat of the sun. For this reason, an increase in atmospheric carbon dioxide means an increase in global temperatures. The amount of carbon dioxide in the atmosphere varies naturally. The amount of atmospheric carbon has increased as a result of human activity, as fossil carbon – that is, oil, coal and natural gas – has been burned to produce energy. We have released carbon dioxide that would otherwise have remained stored forever. In so doing, we have facilitated global warming.

How do we know this? The amount of atmospheric carbon dioxide is measured continuously. Carbon dioxide contents from hundreds, thousands and even millions of years ago have been estimated based on seabed sediments and plant fossils.

The size of the carbon sinks that forests create varies by season and year. Trees serve as carbon sinks during the growing season. If the autumn is warm, the forests are a source of carbon: the soil decomposes, but the growth has already stopped for the year.

The availability of the light, heat and water needed by trees varies, which is why forests store different amounts of carbon in different years. A warm, sufficiently rainy summer spurs forest growth, and the carbon sink is considerable. During a dry summer, growth and the carbon sink are more modest.

During an intense growth period, trees store more carbon than older forests, where growth is slower. Above all, old forests serve as carbon storage. Active forest management has increased the size of Finnish carbon sinks, as Finnish forests on average are younger and grow better than before, as well as increasing the amount of carbon storage, as there are more trees in the forests than a hundred years ago, for example. The trees are sturdier and grow more densely.

At the same time, forests have been used as a source of raw material, and wood has been processed to manufacture various products. These products have been used to replace products containing fossil carbon and reduce fossil carbon dioxide emissions. This phenomenon is known as the substitution effect.

EU wants to lead the way

International climate policy aims to reduce emissions that cause global warming. The European Union wants to lead the way in fighting climate change. To serve this purpose, it has created an emissions trading mechanism: the number of industrial emission rights in Europe is limited and is decreasing in line with the climate targets.

Industrial plants that have reduced their emissions may sell their emission rights to plants that have failed to do so. This is believed to facilitate low-emission production. Emission trading only concerns part of industry.

There are also goals for increasing the use of renewable energy. By 2020, Finland must use renewable sources to produce 38 per cent of the energy it consumes.

In addition, targets have been suggested for reducing emissions in sectors not included in the emissions trading system. Such industries include construction, agriculture, waste management and traffic, among others. The EU classifies Finland as a wealthy country. Accordingly, at 39 per cent by 2030, the target for Finland for reducing emissions is one of the strictest within the EU.

This target only concerns the sectors not included in the emissions trading system. At the moment, the EU is trying to find ways to integrate the land-use sector and forests into the target.

Historical data to be used to determine the carbon sink size

The European Commission is building a calculation model for determining the target size of the carbon sinks for the member states. The Commission has been calculating the target size within the framework of the proposed LULUCF Regulation. "LULUCF" is an abbreviation of "land use, land-use change and forestry".

The Commission presented its proposal in July 2016. It suggests that member states prepare forestry accounting plans and not allow their intensity of forest use to exceed the levels of 1990–2009.

"The proposal does not explicitly specify a year or figure for comparison purposes. The member states are expected to determine a comparison figure based on the criteria indicated in the proposal. The Commission would like to determine the eventual carbon sink target," says Ahti Fagerblom, Manager, Energy and Climate Policy at Finnish Forest Industries.

Regarding Finland, it is problematic that our bioeconomy is based on increasing the use of wood, but the level of felling has been low in recent years and was at a record low in 2009.

According to an estimate provided by the Natural Resources Institute Finland (Luke), Finland's forests would be a source of emissions regardless of the fact that they store more carbon than their use releases. "Higher levels of felling would enable the forests to remain a carbon sink, albeit a smaller one. The forests will continue to have a cooling effect on the climate, and there should be no sanctions for that," Fagerblom points out.

Fagerblom wonders why the emission reduction targets for Finland are so strict and why, at the same time, there seems to be a tendency to limit the emission reductions that using wood makes possible.

"There is still time to make a difference. The Commission's proposal is just that: a proposal. The end result is still being discussed. There are still many opportunities to make an impact, but those opportunities must be seized," says Fagerblom.

The carbon sink decision is significant for the national economy

"Even if the level of felling increased considerably, the forests would remain a significant carbon sink. In the Commission's proposal, a biological carbon sink is turned into carbon emissions using various calculation methods. This is pure politics," says Juha Hakkarainen, Forest Director at the Central Union of Agricultural Producers and Forest Owners (MTK).

If the Commission's proposal were approved in its current form, Finland would only have poor options. "We would either need to limit our forest use, or the state would need to purchase compensation somewhere at some price. We would need to pay for non-existent emissions," says Hakkarainen.

Failure to reach the carbon sink target would compromise Finland's reputation. Combined with payments, it could also lead back to the first option: limited felling.

"The proposed LULUCF Regulation would cast a shadow over the future of the entire forest sector. Finland swears by the bioeconomy, but the regulation would turn the bioeconomy into a hindrance. We would need to limit the manufacture of the very products that we could use to replace fossil products," Hakkarainen points out.

The forest sector is the engine of the Finnish economy. Last year, it regained its position as the largest generator of export revenues. "Limiting the forest sector means limiting the entire national economy," says Hakkarainen.

Text: Krista Kimmo
Illustration on the video: Kanerva Karpo