Radiative forcing of climate change

Scientifically this proposal focuses on one selected topic within the research field of climate change, namely on the processes causing climate change. Gaps in the knowledge of this topic are significant and quantitative estimates of climate forcing are u ncertain in many cases. This proposal is related to changes in the stratosphere, tropospheric aerosols, and processes caused by land use changes. Most of the research on stratospheric changes will be on the anthropogenic change in water vapour and the imp act of variation in the solar irradiance on ozone. Over the last few years there has been a substantial improvement in the understanding of aerosols and their radiative properties. This has resulted in improved global aerosol models and better calculation s of radiative forcing estimates. However large uncertainties are still present and the main aim of the work on tropospheric aerosols is to further reduce the uncertainties in the radiative effect of aerosols. In the context of radiative forcing land use changes have received relatively weak attention, although this is a central point in the understanding of future climate change. In this proposal work on the land use change and the hydrological cycle is linked; and specifically the work will focus on sur face albedo changes and water vapour changes. Most of the work will be oriented towards producing results that are of importance for the IPCC Fourth Assessment Report (AR4). The proposal is for a 3 year research position including funds for the applicant to act as lead author in the IPCC AR4 process. The proposal also provides an opportunity for Norwegian involvement in a large aerosol and climate field campaign. Several studies in the project will be made in collaboration with international experts, bui lding upon common work over several years. Methods to be used are in the forefront in this part of the science, mainly a group of atmospheric numerical models.