It has been established that the concentration of methane has more than doubled over the past 100-200 years and that nitrous oxide levels have increased by some 20%. These changes are probably caused by increasing emissions from human activities and possibly from reduction in the capacity of the atmosphere to remove methane. Increased concentrations of both gases can add to the global warming expected from the increasing concentrations of CO2. Changes, during ice ages and other colder periods, probably reflect the response of the biogenic sources in the world's ecosystems. As the earth warms up in the future, these ecosystems may emit more and more CH4 and N2O into the atmosphere, causing a positive feedback on the cycles of these gases and hence on the world's climate. This program has 3 components: 1. recovery of ice core samples from Vostok Station; 2. laboratory analyses of ice samples to measure CH4 and N2O over the 150,000 years spanned by the core and supplemented by analyses of other available cores. The expected results are primary data on the changes of N2O during heating and cooling of the earth and more complete data on the response of CH4 to climatic changes; 3. delineate the patterns in the data and assess the causes of the changes of concentrations that occur during ice ages. These analyses will provide information on how the sources and sinks of these gases respond to climatic changes and may provide a basis for understanding what may occur in the future.
