Geoscience Reference
In-Depth Information
significantly from the global mean curve.
Some areas have actually experienced tem-
perature drops and others have remained
the same, but most have experienced a
warming atmosphere.
Until recently Antarctica appeared to be
the only continent that was not warming.
Because of the size of the continent and
the sparse number of weather stations,
this was never a certainty. In 2009 two
separate, peer-reviewed reports indicated
that the Antarctic continent had warmed
considerably over the preceding fifty years.
One study based on ice cores on the Ant-
arctic Peninsula showed a warming of 2.7
degrees Celsius (4.9 degrees Fahrenheit)
during that period. A second study based
on satellite observations on the West Ant-
arctic Ice Sheet suggested a warming rate
of 0.1 degree Celsius (0.2 degree Fahren-
heit) per year over the preceding decade.
Both these rates of temperature increase
are much higher than the global warming
average.
The atmosphere is not the only Earth
body that is warming. In fact, 80% of the
Earth's heat gain over the last fifty years
has been stored in the uppermost two
thousand feet of the ocean and not in the
atmosphere, which accounts for the other
20%. The difference is due to the far greater
capacity of ocean waters to absorb heat.
The physics of air, water, and heat dictate
that the increase in heat content of the
oceans produces a much smaller rise in
temperature than a similar amount of heat
absorption in the atmosphere. Nonetheless
the volume of water in the oceans is so im-
mense that a small rise in temperature can
cause a significant expansion of the water,
which has been the cause of most of the sea
level rise that we have experienced over the
last hundred years. This is discussed fur-
ther in chapter 6.
The bottom line:
the entire globe is warming.
Global climate changes
The impact of global warming on local and
even regional scales is difficult to predict
and remains in the realm of educated guess-
work. It is certain that the Earth's ecosys-
tems will shift as new species are added
(or subtracted), but uncertainties abound.
Unknowns that could produce surprises
include changes in major ocean currents
(such as the Gulf Stream), patterns of cloud
distribution, and storm patterns. How the
human population grows and shifts about
and how land use patterns change will also
greatly influence future climates.
In a very general way, wet regions will
become wetter and dry regions will be-
come drier. As the atmosphere warms, it
will contain more water vapor, leading to
more rainfall globally. Also, as the air gets
warmer, evaporation will increase, snatch-
ing water up from the land. Probable re-
gional trends include increasing aridity
around the Mediterranean, South Africa,
Southern and Central Australia, Chile and
Argentina, Pakistan, Mexico, and the south-
