Geoscience Reference
In-Depth Information
The magnitude of the response of global temperature to a radiative forcing of given magnitude,
or set of forcings in combination, depends on the climate feedbacks. Positive feedbacks dominate,
and hence act to amplify the temperature response to a forcing. In terms of human-induced climate
change, the most important are the fast water vapor and ice-albedo feedbacks.
Climate projections through the twenty-first century, assuming a variety of emission scenarios
for greenhouse gases and aerosols, indicate a mean global temperature increase in the range
of 2-4
o
C by the year 2100, together with sea-level rises of 200-500mm. Given the rapid growth of
greenhouse gas concentrations in recent decades, the effects of ice sheet dynamics and other wild
cards in the system, these may be underestimates. The Arctic will eventually become free of sea
ice in summer. Warming will also be accompanied by continued shrinking of glaciers, ice caps and
permafrost, changes in the hydrologic cycle, atmospheric circulation, and vegetation.
Critical research needs include improved understanding of climate feedbacks, including
feedbacks in the carbon cycle, and the role of the oceans in the uptake of heat and carbon dioxide.
•
Examine the figures showing climatic time series in Chapter 13 for evidence of changes in mean
and variance and consider where step function changes have occurred and where trends can be
detected.
•
What are the different climate forcing factors at work on geological and historical timescales?
•
What are the main advantages and limitations of different types of proxy records of paleoclimate?
Consider the climatic variables that may be inferred and the temporal resolution of the
information.
•
What are the main reasons for uncertainties in projections of climate for the year 2100?
•
What are some of the possible impacts of projected climate changes in your region and country?
REFERENCES AND FURTHER
READING
Bradley, R. S. and Jones, P. D. (eds) (1992) Climate
Since A. D. 1500, Routledge, London, 679pp.
[Collected contributions focusing on the Little Ice
Age and subsequent changes from proxy,
historical and observational data]
Crowley, T. J. and North, G. R. (1991) Paleo-
climatology, Oxford University Press, New York,
339pp. [Surveys the pre-Quaternary and
Quaternary history of the earth's climate,
presenting
Books
Adger, W. N. and Brown, K. (1995) Land Use and the
Causes of Global Warming, John Wiley & Sons,
New York, 282pp. [Greenhouse gas emissions
from land use sources and the effects of land-use
changes]
Bradley, R. S. (1999) Quaternary Paleoclimatology:
Reconstructing Climates of the Quaternary,2nd
edn, Academic Press, San Diego, 683pp. [Details
methods of paleoclimatic reconstruction, dating
of evidence and modeling paleoclimates;
numerous illustrations and references]
observational
evidence
and
modeling results]
Dyurgerov, M. and Meier, M. F. (2005) Glaciers and
the Changing Earth System: A 2004 Snapshot,
Occasional Paper 58, Institute of Arctic and
Alpine Research, University of Colorado,
Boulder, CO, 118pp. [An evaluation of recent
global changes in glacier mass balance]
