Understanding and managing the risks to health and environment from globalatmospheric change: A synthesis

The global atmosphere is changing. Anthropogenic activities are increasing the concentrations of greenhouse gases and releasing synthetic compounds th at deplete stratospheric ozone and increase UV-B radiation. Changes of temp erature in the Northern Hemisphere during the past century strongly suggest that we are now in a period of rapid global warming relative to the past m illennium. Increased concentrations of greenhouse gases are absorbing outgo ing infrared radiation in the lower atmosphere, warming the troposphere and cooling the lower stratosphere. Research is beginning to indicate that los ses of stratospheric ozone and increases of greenhouse gases are interdepen dent. Increased greenhouse gases have been implicated in the observed stren gthening of stratospheric wind vortices around both poles, in turn setting the stage for further depletion of ozone and increases in UV-B radiation. A lthough the uncertainties are still large enough to make it difficult to as sess health and ecological risks, decisions must be made. Research on indic ators of risks to human health and the environment can help reduce the unce rtainties in these risks and shorten the time between recognizing the risks of atmospheric change and taking concrete mitigative and adaptive actions.