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The dramatic growth of the human impact on the environment has led to the concept of "global change", which encompasses not only the idea that our environment is changing on a global scale, but also that the changes cut across all components of the Earth's system and their associated scientific disciplines. In particular, it has turned out that many changes in componenents of the Earth's system can influence the whole system, and that feedbacks and long-range effects are key characteristics on the system's nonlinear behaviour. For example, if the composition of the atmosphere changes through an addition of CO2, the climate warms and plants grow faster, etc. These changes in turn affect the composition of the atmosphere, including CO2, so that multiple feedbacks and interconnections are generated.
It is clear that global atmospheric carbon dioxide levels and temperatures will continue to increase well into the 21st century, but other climate feedbacks such as concomitant increases in biospheric organic trace gases have not yet been considered. Moreover, the degree to which the terrestrial biosphere, particularly plants and soils, contributes to the atmospheric burden of climate-relevant trace gases is poorly understood. Very recently the unexpected observation that climate-relevant trace gases are produced in plants has demonstrated that the plant biosphere could play an important role in the budgets of methane, chloromethane and bromomethane, gases which are known to play a role in the natural cycles of global warming and ozone depletion. In this context it is important to note that methane is the most abundant organic greenhouse gas in the atmosphere; chloromethane and bromomethane are the most abundant chlorinated and brominated organic gases in the atmosphere, respectively.
The goal of our research group is to explore the formation of biospheric climate-relevant volatile organic compounds (VOCs) and to study their life-cycle utilising a stable isotope approach. We will focus mainly on the three gases, methane, chlormethane and bromomethane but other C1 VOCs such as iodomethane, methanol, chloroform and bromoform which also play a role in atmospheric chemistry will also be of interest. Particular emphasis will be given to the fact that biospheric emissions of these gases are expected to drastically change in the 21st century as a response to global change. Climate feedbacks in the past will also be considered. Once we have identified and quantified all the major sources and have established the environmental parameters that control the fluxes of biospheric C1 VOCs numerical models of different complexity will be applied to stimulate past and future scenarios of the atmospheric burden of these atmospherically important compounds. This should enhance our understanding of the life-cycle of C1 VOCs in the past, present and future and consequently provide insights into possible feedback mechanisms in the biosphere-atmosphere system.
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