Geoscience Reference
In-Depth Information
4.2.1 Temperature
According to the fourth assessment report of the Intergovernmental Panel on Climate
Change (IPCC,
2007
), the global mean surface air temperature increased by 0.74 °C while
the global mean sea surface temperature rose by 0.67 °C over the last century (Trenberth and
Josey,
2007
). Models predict that the effect of increased amounts of climate-altering gases
will lead, before the end of this century, to an increase in air temperature ranging between
1.4and5.8°C(IPCC,
2007
).Duringthelast10-15years,seawatertemperaturesthroughout
much of the globe have changed at unprecedented rates. The direct consequences of these
changes have been: the rapid disappearance of sea ice covering the Arctic; the melting of
glaciers; a reduction in the volume of Antarctic ice sheets; raising of sea levels and increas-
ing storm events in the seas; high variability of precipitation and more frequent occurrences
However, temperature variations do not only affect important environmental variables such
as local currents, water column stratification, nutrient cycling, and primary production, but
also metabolic rates of marine organisms (McGowan
et al.,
1998
). All of these changes,
induced by variability in temperature, strongly affect population and community dynamics
and, over time, community structure and function. Moreover, temperature appears as the
primary environmental factor in driving diversity at the large geographic scale (Tittensor
et
tensor
et al.,
2010
).