Motivation and scientific scope - detailed information
Since the pre-industrial era, the global environment has changed dramatically. First, the chemical composition has evolved in response to intensive agricultural practices and industrial activities. For example, the atmospheric concentration of carbon dioxide has increased by approximately 30 % in the last 150 years, while that of methane has been enhanced by more than a factor 2. At the same time, the atmospheric abundance of tropospheric ozone has increased by a substantial amount (factor 2-3 in the Northern Hemisphere) and the load of sulfate and nitrate aerosols has increased dramatically in industrialised and urbanised regions. Fossil fuel combustion in the Northern mid-latitudes and biomass burning in the tropics have been major perturbing factors. As a result, the radiative forcing to the climate system has changed substantially, but the response of the Earth system to these anthropogenic effects is difficult to assess.
The analysis of temperature records shows that, on the global scale, the Earth has warmed by 0.5-0.7 K since the industrial revolution. Although some of this change may represent natural fluctuation in the climate system, there is growing evidence that it is associated with human-related perturbations.
Also in the history of Earth, climate and global scale fluxes of matter have undergone significant variations, with the ice ages and interglacials in the past few hundred thousand years interspersed with abrupt climatic changes such as the Oeschger -Dansgaard events or the Younger Dryas period.
These changes of the global environment, with its climate and fluxes of matter, represent a major challenge of modern environmental research in different ways. First, there are the questions related to the dynamics of global, specifically climate change, for instance with respect to the mechanisms behind the Oeschger-Dansgaard events, the role of vegetation in controlling global change, or the sensitivity to increased concentrations of anthropogenic substances in the atmosphere. On the other hand, climate is no longer primarily an enterprise of fundamental research, but it is closely related to the management of the Earth system. This management requires the study of human influences, such as deforestation, and of the sensitivity of climate sensitive systems, in particular ecosystems. These processes are usually regional or even local in character. Thus any study of the dynamics of global change and the construction of plausible scenarios of future change needs to be combined with studies on the regional scale by downscaling global change (e.g. in terms of the statistics of extreme events) and upscaling regional changes (e.g. emissions).
