Geoscience Reference
In-Depth Information
variables such as temperature, precipitation, altitude, geogra-
phy and the presence of other species.
16.2
Climate change
Climate change is the long-lasting and significant change in the
statistical distribution pattern of weather over a long period of
time that can range from decades to millions of years. The sig-
nificant factors responsible for climate change include oceanic
processes (such as oceanic circulation), variations in radiation
received by Earth, plate tectonics and volcanic eruptions and
human-induced alterations of the natural world. The most gen-
eral definition of
climate change
is a change in the statistical
properties of the climate system when considered over long
periods of time, regardless of cause. Nowadays, in most cases,
climate change specifically refers to climate change caused by
human activity, as opposed to changes in climate that may have
resulted as part of Earth's natural processes. Under this sce-
nario, climate change has become synonymous with anthropo-
logical global warming. This climate change is being chiefly
expressed in terms of fluctuating weather variables including
temperature, precipitation, humidity, cyclone, storms and so on.
Causes of
climate change
Factors that are responsible for climate change are known as cli-
mate forcing or 'forcing mechanisms' including processes such
as variations in solar radiation, deviations in the Earth's orbit,
mountain building and continental drift, and changes in green-
house gas concentrations. Forcing mechanisms can be either
'internal' or 'external'. Internal forcing mechanisms are natu-
ral processes within the climate system itself. External forcing
mechanisms can be either natural (e.g. changes in solar output) or
anthropogenic (e.g. increased emissions of greenhouse gasses).
16.3
Impacts of climate change on biodiversity
At present-day, climate change has become a major challenge to
the sustainability of biodiversity worldwide. In the atmosphere,
gasses such as water vapour, carbon dioxide and methane act
like the glass roof of a greenhouse by trapping heat and warm-
ing the planet. These gasses are known as greenhouse gasses.
As a result of human activities (such as farming activities, land
use changes, burning of fossil fuels etc.), the normal level of
