Mires and peatlands modify global climate

In total the carbon uptake from the atmosphere of northern mires and peatlands exceed their emissions. Therefore, these lands have a cooling effect on climate.

"If there were no mires or peatlands, the world would be warmer. It is estimated that they provide a cooling effect equivalent to 0.5 W per square meter", says Mats Nilsson, Professor at the Swedish University of Agricultural Sciences (SLU) and speaker at the International Peat Congress 2012 (IPC2012).

Mats Nilsson also chairs the theme of IPC2012 dealing with the role of mires and peatlands in the greenhouse gas exchange between land and atmosphere.

The fens can become sources of greenhouse gases

In research studies Mats Nilsson and his Canadian research partner Nigel Roulet have seen that different types of mires respond differently to changes in the water balance. The latter is expected to be impacted by the current climate change. By the water balance we mean the relationship between the amount of water supplied to and departing from a mire and the storage change for a given time period.

Their results, not yet published, show that bogs can adapt to a changing water balance in a gradual manner. This means that bogs continue to absorb carbon from the atmosphere despite a major change in water balance. Fens however, react completely different.

" We see that a drastic change in water balance will cause fens to stop their carbon uptake. Instead they become sources of greenhouse gases to the atmosphere. The transition occurs in an abrupt manner, when the change in the water balance has reached a certain threshold", says Mats Nilsson.

This new knowledge will, together with the many other presentations during IPC2012, give a basis for revising the two-year old Strategy for Responsible Peatland Management. The proposed revisions will be discussed and presented at the end of the congress.