Climate change impacts and vulnerability in Europe 2016

Changes in the climate system
3.3.4 Glaciers
Key messages
• The vast majority of glaciers in the European glacial regions are in retreat. Glaciers in the European Alps have lost
approximately half of their volume since 1900, with clear acceleration since the 1980s.
• Glacier retreat is expected to continue in the future. It has been estimated that the volume of European glaciers will
decline between 22 and 84 % compared with the current situation by 2100 under a moderate greenhouse gas forcing
scenario, and between 38 and 89 % under a high forcing scenario.
• Glacier retreat contributed to global sea level rise by about 0.8 mm per year in 2003–2009. It also affects freshwater
supply and run-off regimes, river navigation, irrigation and power generation. Furthermore, it may cause natural hazards
and damage to infrastructure.
Relevance
Glaciers are particularly sensitive to changes in the
global climate because their surface temperature is
close to the freezing/melting point (Zemp et al., 2006).
When the loss of ice, mainly from melting and calving in
summer, is larger than the accumulation from snowfall
in winter, the mass balance of the glacier turns negative
and the glacier shrinks.
Glaciers are an important freshwater resource and act
as 'water towers' for lower lying regions. The water
from melting glaciers contributes to water flow in rivers
during summer months and thus helps maintain water
levels for irrigation, hydropower production, cooling
water and navigation. The effects of a reduction in
glaciers are, however, complex and vary from location
to location (SGHL and CHy, 2011). Glacier melting also
contributes to global sea level rise (Marzeion et al.,
2012; Gardner et al., 2013).
Past trends
A general loss of glacier mass since the beginning
of the measurements has occurred in all European
glacier regions, except some glaciers in Norway
(Figure 3.12). The Alps have lost roughly 50 % of their
ice mass since 1900 (Zemp et al., 2008, 2015; Huss,
2012). Norwegian coastal glaciers were expanding
and gaining mass up to the end of the 1990s owing
to increased winter snowfall on the North Atlantic
Coast; now these glaciers are also retreating (Nesje
et al., 2008; Engelhardt et al., 2013; Hanssen-Bauer
et al., 2015). Some ice caps at higher elevations
in north-eastern Svalbard, Norway, seem to be
increasing in thickness, but estimates for Svalbard as
a whole show a declining mass balance (Bevan et al.,
2007; Lang et al., 2015). The centennial retreat of
European glaciers is attributed primarily to increased
summer temperatures. However, changes in winter
precipitation, reduced glacier albedo due to the lack
of summer snowfall and various other feedback
processes, such as the increasing debris cover on the
glacier, can influence the behaviour of glaciers, in
particular on regional and decadal scales.
The melting of glaciers is contributing significantly
to global sea level rise. For the period 2003–2009,
the global contribution was 0.71 ± 0.08 mm per year,
accounting for 29 ± 13 % of the observed sea level rise
(Gardner et al., 2013; Vaughan et al., 2013).
Projections
The retreat of European glaciers is projected to
continue throughout the 21st century (Figure 3.13).
One study estimates that the volume of European
glaciers will decline between 22 and 84 % relative to
their extent in 2006 under a moderate greenhouse gas
forcing scenario (RCP4.5) and between 38 and 89 %
under a high forcing scenario (RCP8.5) (all European
regions combined) (Radić et al., 2014). The relative
volume loss is largest in central Europe (83 ± 10 % for
RCP4.5 and 95 ± 4 % for RCP8.5). Similar results were
achieved in other studies (Marzeion et al., 2012; Huss
and Hock, 2015). In Norway, nearly all smaller glaciers
are projected to disappear and, overall, glacier area as
well as volume may be reduced by about one-third by
2100, even under the low SRES B2 emissions scenario
(Nesje et al., 2008).
Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report
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