Climate change impacts and vulnerability in Europe 2016

Changes in the climate system
3.3 Cryosphere
Key messages
• Consistent with a warming climate, observations confirm the decrease of snow cover, the shrinking of glaciers, increased
melting of the large polar ice sheets in Greenland and Antarctica, and the declining area and thinning of Arctic sea ice.
• Further reductions of the cryosphere are projected in the future. The projected changes vary across regions and
indicators, and there are large uncertainties in some of the projections.
• The melting of ice and snow and the thawing of permafrost cause positive feedback loops that can accelerate climate
change further.
• Changes in the cryosphere affect global sea level, many species, ecosystems and their services, freshwater supply, river
navigation, irrigation and power generation. The projected changes could increase natural hazards and the risk of damage
to infrastructure. At the same time, they could create new opportunities for navigation and the exploitation of natural
resources in the Arctic region.
3.3.1 Overview
Relevance
The cryosphere includes all permanent or seasonal
snow and ice on land, in the seas, rivers and lakes, and
in the ground (permafrost). It is the second largest
component of the climate system, after the oceans,
with regard to mass and heat capacity. Because of its
importance, the cryosphere features prominently in
climate change literature (AMAP, 2011; Barry and Gan,
2011; Olsen et al., 2012; Vaughan et al., 2013; Key et al.,
2015). The concern for the long-term and irreversible
changes in the cryosphere is receiving increasing
international attention (ICCI, 2015). Recent scientific
work has focused in particular on the Greenland and
Antarctic ice sheets (Shepherd et al., 2012; Joughin
et al., 2014; Noël et al., 2014), as the fate of the ice
sheets has major implications for long-term sea level
rise. In addition, melting of the Greenland ice sheet
can influence the Atlantic meridional overturning
circulation and thereby create a feedback that can
critically influence long-term changes in the climate
system (Blaschek et al., 2014). Another important part
of the cryosphere is the Arctic permafrost, as thawing
of permafrost can lead to major positive feedback
processes, accelerating climate change (Parmentier
et al., 2015; Schuur et al., 2015).
The scientific publications that have been published
since the previous CCIV report (EEA, 2012) confirm the
general patterns of change, but have provided new data
on the melting of the Greenland and Antarctic ice sheets,
suggesting that the mass loss may accelerate and that
there is a risk of irreversible processes at relatively low
levels of air temperature increase. This would imply a
higher rise in sea level than previously assumed.
Snow and ice are important for the global climate
system (see Section 3.1). Much of the sunlight that
hits these surfaces is reflected back into space instead
of warming the Earth. As the melting of snow and ice
leads to expansions of darker surfaces such as water
or ground, more heat is absorbed. These positive
ice-temperature feedback processes are already
accelerating the loss of sea ice in summer and autumn,
which has resulted in higher winter near-surface air
temperatures in the Arctic (Screen and Simmonds,
2010).
Ice and snow are important for many ecosystems.
Some species spend their entire life cycle in areas
dominated by the cryosphere, whereas others are
adapted to temporary snow and ice. Observed
changes in the cryosphere are already affecting
species interactions and entire ecosystems (Post et al.,
2009).
The cryosphere plays an important role in water
management. Two-thirds of the world's freshwater
resources are frozen. Seasonal melting releases water
during the warm season, thereby supporting water
supplies and hydropower. The cryosphere is also
closely linked to sea level. The melting of glaciers and
of the large ice sheets in Greenland and Antarctica is
already contributing significantly to global sea level
rise, and this contribution is expected to increase in the
future.
Changes in the cryosphere have social and economic
consequences by affecting sea ice and the distribution
of permafrost on land. Such changes affect transport
routes, building technology, tourism and recreation,
and opportunities to exploit natural resources.
Furthermore, thawing of permafrost can contribute to
90 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report