1. Reconstruction of paleoatmospheres from ice core records in Greenlandand Antarctica back to > 500,000 years covering at least 5glacial/interglacial cycles; main emphasis is to reconstruct atmosphericCO2 and d13CO2, 2. Global biogeochemical cycles of radiatively importantatmospheric trace gases; biosphere-atmosphere interactions, 3. Stableisotopes in atmospheric CO2 (d13C and d18O) to arrive at improved globalcarbon cycle budgets (in collaboration with C. D. Keeling).Process-oriented studies to determine the significance of 18O inatmospheric CO2, 4. Stable isotopes of Cl and Br in aerosols to determineif Cl and Br radicals are produced in the troposphere, 5. Investigations onCO2, CH4, 85Kr and N2O in the stratosphere (and their isotopic species 13Cand 18O in CO2, 13C, D and 14C and CH4, 15N and 18O in N2O) to determinethe troposphere/stratosphere air exchange rate. Recent experimentalresults on 15N and 18O in stratospheric N2O are not compatible with currentassumptions on stratospheric N2O destruction.

North Atlantic Ocean
North Pacific Ocean