Edited by A. J. McMichael, A. Haines, R. Slooff and S. Kovats
Change and Human Health
The extent and nature
of our industrial and agricultural activities are now so great that the
gaseous composition of the lower and middle atmospheres (the troposphere
and the stratosphere) has begun to change. This is likely to affect the
world's climate, many other of the worldıs natural systems, ground-level
exposure to ultraviolet radiation, and indeed, all life on earth.
that, due to the accumulation of greenhouse gases such as CO2, the climate
will change at a rate much greater rate than human societies have experienced
since the advent --- approximately 10,000 years ago --- of agriculture
and settled living.
in temperature and changes in climate variability in numerous parts of
the world are regarded by many scientists as the first signals of global
climate change caused by human activities.
During the past century,
Earth's global mean surface temperature has increased by about 0.3 - 0.6
degrees C. Climate simulations, using the most advanced computer models,
indicate that global mean surface temperature may have increased by 1-3
degrees C. by the year 2100.
These models also
predict changes in precipitation patterns, including a greater frequency
of heavy precipitation and a corresponding increase in foods.
Global mean sea level
is predicted to rise by between 0.2 meters and 1.0 meter by the year 2100,
and would be expected to continue to rise for several centuries even if
greenhouse gas levels were to be stabilized. The current "best estimate"
predicts a rate of rise in sea level that is two to three times greater
than that experienced during the past 100 years.
Various man-made gases (particularly the halocarbons and N20) have reduced stratospheric ozone levels, especially at higher latitudes. As a result, a greater proportion of solar ultraviolet radiation now reaches Earth's surface. Damage to stratospheric ozone continues, and the rate of overall ozone depletion has risen during the 1990s.
Work on the report began in 1993 following receipt of a grant from the United States Environmental Protection Agency. Further financial resources were obtained from the government of the Netherlands and the three participating UN agencies (WHO,WMO, and UNEP, with WHO designated the coordinating agency). An international task group of experts was formed under the direction of A. J. Michael, and met three times in two years. The views expressed in the report reflect the consensus reached by this Task Group and do not necessarily reflect the the policies of the participating agencies.