Permafrost thermal state in the polar Northern Hemisphere during the international polar year 2007–2009: a synthesis

Abstract

The permafrost monitoring network in the polar regions of the Northern Hemisphere was enhanced during the International Polar Year (IPY), and new information on permafrost thermal state was collected for regions where there was little available. This augmented monitoring network is an important legacy of the IPY, as is the updated baseline of current permafrost conditions against which future changes may be measured. Within the Northern Hemisphere polar region, ground temperatures are currently being measured in about 575 boreholes in North America, the Nordic region and Russia. These show that in the discontinuous permafrost zone, permafrost temperatures fall within a narrow range, with the mean annual ground temperature (MAGT) at most sites being higher than À28C. A greater range in MAGT is present within the continuous permafrost zone, from above À18C at some locations to as low as À158C. The latest results indicate that the permafrost warming which started two to three decades ago has generally continued into the IPY period. Warming rates are much smaller for permafrost already at temperatures close to 08C compared with colder permafrost, especially for ice-rich permafrost where latent heat effects dominate the ground thermal regime. Colder permafrost sites are warming more rapidly. This improved knowledge about the permafrost thermal state and its dynamics is important for multidisciplinary polar research, but also for many of the 4 million people living in the Arctic. In particular, this knowledge is required for designing effective adaptation strategies for the local communities under warmer climatic conditions.

Modeling the temperature evolution of Svalbard permafrost during the 20th and 21st century

“…Lütschg et al, 2008), while Engelhardt et al (2010) showed that differences in the timing of a thick snow cover have a similar influence on ground temperature as different forcing climate scenarios. Recently, Christiansen et al (2010) and Romanovsky et al (2010b) demonstrated the large differences of nearsurface ground temperatures between two adjacent boreholes with different snow cover in Svalbard. Deeper ground temperatures will, however, become more similar because of the lateral heat transfer, causing temperatures at greater depths to be integrated over larger surface areas.…”

Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta

“…Deposits of the Holocene cover exposed on top of the Ice Complex unit consist of brownish-black, cryoturbated silty sand with numerous small peat inclusions and are characterized by smaller ice wedges. Deposits of thermokarst depressions are composed of cryoturbated silty sands, numerous plant remains, and peat inclusions, and contain syn- genetic ice wedges about 3 to 5 m wide (Schirrmeister et al, 2003).…”

“…According to Schirrmeister et al (2003) and Wetterich et al (2008) we assume that the average boundary between Ice Complex deposits and underlying fluvial sands lies between 15 and 20 m a.r.l. For calculation purposes in the GIS we set the height of the boundary to 17 m a.s.l.…”

“…During a field campaign in summer 2008, the relief characteristics and lake bathymetries were investigated in detail www.the-cryosphere.net/5/849/2011/ The Cryosphere, 5, 849-867, 2011 in one thermokarst basin with three large lakes located in the south of Kurungnakh Island (Morgenstern et al, 2008b;Ulrich et al, 2010).…”

“…Climate warming in most northern high-latitude permafrost regions (ACIA, 2004) has resulted in widespread warming of permafrost, and also, in some cases, permafrost degradation during the last few decades (Romanovsky et al, 2010). Thawing of permafrost soils and sediments is often accompanied by the release of old organic carbon (Anisimov and Reneva, 2006;Zimov et al, 2006b;Schuur et al, 2008;Grosse et al, 2011a) and changes in water and land surface energy balances , which may influence atmospheric processes via feedback mechanisms (Chapin et al, 2005;Walter et al, 2006;Schuur et al, 2009).…”