The UN Climate Conference that is scheduled to start on November 28 in Durban is under intense pressure to succeed; since the Kyoto Protocol expires in 2012, it is imperative to supersede it with an internationally binding follow-up agreement. The joint committee of German chemical societies "Chemistry, Air Quality and Climate" (CLK) agrees that a new agreement must be tightened significantly. Moreover, the discussions should not focus exclusively on greenhouse gases, classical air pollutants have to be taken into account as well. These pollutants also influence the climate, either directly or indirectly. In this context, chemical reactions in the atmosphere play an important role. "To date, too little attention has been paid to the chemical component of climate change", says Prof. Dr. Reinhard Zellner of the University of Duisburg-Essen, the chairman of the joint committee.
Besides greenhouse gases such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4), classical air pollutants, including carbon monoxide (CO), nitrogen oxides (NOx), ammonia (NH3), sulphur dioxide (SO2), volatile hydrocarbons (VOC), particulate matter and soot, also impact on climate. These pollutants are all short-lived, but have a severe influence on the chemistry of the atmosphere, for example on the formation of ozone (O3) and aerosols. Ozone and aerosols have a direct effect on climate. Air pollutants that have been widely disregarded in the discussion on climate so far are of diverse origins, such as agriculture, traffic, energy generation including domestic heating, but also derive from biogenic sources.
Recent studies indicate that a reduction of methane, ozone and soot in the atmosphere could slow down the temperature rise over the next decades. "We are buying time if we improve air quality by reducing soot and methane emissions and minimizing ozone formation . Of course, we must also continue to lower carbon dioxide emissions significantly. At all events, we can no longer stop temperature rise and will most probably not be able to avoid an increase of at least 2 degrees by the end of this century. We still have the chance, however, to prevent a more drastic temperature increase. Time is an advantage", says Zellner.
The three chemical societies, Gesellschaft Deutscher Chemiker (GDCh), Gesellschaft für Chemische Technik und Biotechnologie (DECHEMA) and Deutsche Bunsen-Gesellschaft für Physikalische Chemie (DBG), have been involved in chemical processes in the atmosphere and their impact on climate since 1995 when they initiated the joint committee Chemistry, Air Quality and Climate. The panel does not examine chemical processes in isolation; climate depends on many other parameters: on radiation physics and thermodynamics, anthropogenic and biogenic emissions, interactions between the atmosphere, the oceans and ice surfaces and their diverse feedback, and on cloud and aerosol microphysics. For this reason the committee consists of members not only of chemistry, but also from physicists, meteorologists, biologists, engineers, medics and ecologists.
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