Water uptake and cloud droplet formation on organic aerosols. The consequences for the climate
Adam Kristensson (project leader)
Summary of results with list of publications from Copenhagen Centre for Atmospheric Research.
Email: adam.kristensson@comhem.se
Atmospheric particles jeopardize climate and health.
Atmospheric airborne (aerosol) particles have several sources: vehicle exhausts, flue gases, sea spray, forest fires, wood and coal fires, mechanical soil particles, gas-to-particle transformation in the atmosphere, cigarette smoke, etc. Several of these are of course anthropogenic and may affect both health and climate - health through the inhalation of noxious particles and climate through the reflection of solar radiation by particles (the direct effect) and the formation of cloud droplets which, in turn, reflect solar radiation (the indirect effect).
The magnitude of the indirect effect is very uncertain at present, but may be of the same order as the heating effect of the greenhouse gas carbon dioxide. Particles complicate efforts to alleviate the greenhouse effect. When the emission of greenhouse gases is reduced, a reduction in particulate pollutants is also often achieved at the same time since they often have the same sources. While greenhouse gases persist for several decades in the atmosphere, particles have a life of only a week. In other words, the "masking" cooling effect of aerosol particles may disappear when attempts are made to reduce the emission of greenhouse gases, and there is a temporary steep rise in the heating effect. It is essential that the origin and magnitude of the indirect effect should be correctly determined. It is therefore of great urgency to reduce the quantity of greenhouse gases in the atmosphere in order that we may have a reasonable chance of keeping climate changes down to a maximum of two degrees. Attempts to retain a reasonable quantity of particles in the air to prevent a rapid rise in heating is not a good option since in that case we do not reduce the millions of premature deaths all over the world that are caused by particles.
Turnover and emission of greenhouse gases from rivers, lakes and wetlands in Pantanal. Brazil
David Bastviken (project leader)
Summary of results from Biochemistry, Stockholm University.
Email: david.bastviken@geo.su.se
Methane (CH4) is a greenhouse gas that accounts for ca 20% of the increase in the greenhouse effect over the latest century. The quantity of methane in the atmosphere has also increased considerably during the same period. Wetlands and lakes are important methane sources globally, and contribute to the total non-anthropogenic emissions. Unfortunately, however, methane emissions are probably underestimated owing to lack of knowledge of tropical emissions. This project has been instrumental in enabling participation in an international research effort to study the turnover and emissions of methane in one of the world's largest tropical wetland regions in Brazil.
Work entailed amplification of previous measurements through detailed studies of how methane emissions vary over time and space. Processes such as methanogenesis and methane oxidation were also of interest. Studies were also made of the significance of plants for the emissions. The objective was to contribute to a sharing of knowledge concerning metrology and to develop research hypotheses with participants from other countries.
The preliminary results indicate that tropical methane emissions from lakes are considerably higher than those from lakes in temperate and boreal zones. It was established that, although the floating vegetation which dominates Pantanal contributed to the increasing methane fluxes indirectly by supplying organic matter to the sediment, it had no direct effect by e.g. transporting gas through the tissues in the same way as some aquatic plants.
Responsible for this page: Birgitta Bruzelius