There are, however, caveats: (1) multidecadal fluctuations in Arctic — subarctic climate and
sea ice appear most pronounced in the Atlantic sector, such that the pan-Arctic signal may be substantially smaller [e.g., Polyakov et al., 2003; Mahajan et al., 2011]; (2) the sea - ice records synthesized here represent primarily the cold season (winter — spring), whereas the satellite record clearly shows losses primarily in summer, suggesting that other processes and feedback are important; (3) observations show that while recent sea - ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200
ice appear most pronounced in the Atlantic sector, such that the pan-Arctic signal may be substantially smaller [e.g., Polyakov et al., 2003; Mahajan et al., 2011]; (2) the
sea -
ice records synthesized here represent primarily the cold season (winter — spring), whereas the satellite record clearly shows losses primarily in summer, suggesting that other processes and feedback are important; (3) observations show that while recent sea - ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200
ice records synthesized here represent primarily the cold season (winter — spring), whereas the satellite record clearly shows losses primarily in summer, suggesting that other
processes and
feedback are important; (3) observations show that while recent
sea -
ice losses in winter are most pronounced in the Greenland and Barents Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200
ice losses in winter are most pronounced in the Greenland and Barents
Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 20
Seas, the largest reductions in summer are remote from the Atlantic, e.g., Beaufort, Chukchi, and Siberian
seas (National Snow and Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 20
seas (National Snow and
Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200
Ice Data Center, 2012, http://nsidc.org/Arcticseaicenews/); and (4) the recent reductions in
sea ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 200
ice should not be considered merely the latest in a sequence of AMOrelated multidecadal fluctuations but rather the first one to be superposed upon an anthropogenic GHG warming background signal that is emerging strongly in the Arctic [Kaufmann et al., 2009; Serreze et al., 2009].
Based on the understanding of both the physical
processes that control key climate
feedbacks (see Section 8.6.3), and also the origin of inter-model differences in the simulation of
feedbacks (see Section 8.6.2), the following climate characteristics appear to be particularly important: (i) for the water vapour and lapse rate
feedbacks, the response of upper - tropospheric RH and lapse rate to interannual or decadal changes in climate; (ii) for cloud
feedbacks, the response of boundary - layer clouds and anvil clouds to a change in surface or atmospheric conditions and the change in cloud radiative properties associated with a change in extratropical synoptic weather systems; (iii) for snow albedo
feedbacks, the relationship between surface air temperature and snow melt over northern land areas during spring and (iv) for
sea ice feedbacks, the simulation of
sea ice thickness.