Climate change, impacts and vulnerability in Europe ... - MemoFin.fr

Changes in the climate systemBox 2.5Lowland permafrost in sub-arctic palsa miresLowland permafrost in Europe mainly exists in thenorthern parts of Norway, Sweden, Finland and Icelandin palsa mires. Palsas are peat mounds with an icecore that is frozen throughout the year. Palsa mires arediverse environments with unique geomorphologicalprocesses and a rich diversity of, for example, birdspecies. The extent and abundance of palsa mireshave declined since the 1960s in Sweden, Finlandand Norway (Zuidhoff and Kolstrup, 2000; Luoto andSeppälä, 2003; Direktoratet for Naturforvaltning,2012). The depth of the active layer has increasedin northern Sweden during the period 1978–2006(Åkerman and Johansson, 2008).The spatial distribution of palsa mires is stronglycorrelated with climate. Projections of the locationsof palsa mires in northern Fennoscandia for the21st century suggest it to be likely (> 66 %) thatpalsa mires will disappear completely by the end of the21st century under medium (A1B; see Figure 2.18)and moderately high (A2) emissions scenarios (Fronzeket al., 2010). For a low emissions (B1) scenario, it wasmore likely than not (> 50 %) that conditions wouldremain suitable over a small fraction of the currentpalsa distribution until the end of the 21st century.A decline in extent and abundance of palsa miresis expected to have a significant influence on thebiodiversity of sub-arctic mires and on regional carbonbudgets.Figure 2.18 Probability of complete lossof northern Fennoscandianareas suitable for palsas in the21st centuryProbability (%)1009080706050403020100201020202030204020502060207020802090Note:Probability of complete loss of northernFennoscandian areas suitable for palsas duringthe 21st century estimated using a probabilisticprojection of climate change for the SRES A1Bscenario.Source: Adapted from Fronzek et al., 2010.Climate change, impacts and vulnerability in Europe 201285