LEDLEY, TAMARA SHAPIRO. TERC, Cambridge, MA 02140. - Global climate change: An Earth system perspective.
The Earth system, encompassing the atmosphere, hydrosphere, geosphere,
cryosphere, and biosphere, is very complex with each component
affecting and being affected by every other component on a wide range
of time and space scales ranging from seconds to the age of the Earth
and from microscopic to thousands of kilometers. As a result of this
complexity the implications of particular climate changes for each of
the components of the Earth system, the predication of future climate
change, and the identification of causes of climate change are very
difficult to determine.
Worldwide temperature measurements
indicate that there has been a warming of the global annual mean
surface temperature of between 0.3oC and 0.6oC
over the last 150 years. However, this warming has not been steady,
with fluctuations amounting to a significant fraction of the overall
warming. Such changes in the surface temperature have implications
for other parts of the climate system including precipitation,
evaporation, sea level, and the biosphere. In this talk the kinds of
changes that have been observed over the last 150 years and
predictions of changes for the next 100 years will be discussed. We
will explore the impacts and potential impacts of these changes on the
different components of the Earth system. Finally, the possible
causes of the observed and predicted climate changes and the
difficulty of identifying the causes with respect to natural
variability and anthropogenic influences will be discussed.
Key words: climate change, Earth system science