7.01.00 - Impacts of air pollution and climate change on forest ecosystems
Mission: to promote international cooperation, to encourage an interactive process between scientists, policy makers and representatives of local to regional governments and institutions, in order to share scientific knowledge and harmonize effective strategies aimed to reduce the risk for forests related to air pollution and climate change.
Rationale: There is an increasing awareness in both the science and policy communities of the importance of addressing the linkages between the traditional air pollutants and greenhouse gases. Many air pollutants and greenhouse gases have not only common sources, but also their emissions interact in the atmosphere, and may join to cause a variety of environmental impacts on the local, regional and global scales. Many air pollutants contribute to the Earth’s radiative forcing. Examples are nitrogen oxides, carbon monoxide and non-methane volatile organic compounds which are precursors to tropospheric ozone. Tropospheric ozone is particularly relevant for the linkages between climate change and air pollution. Climate change, on the one hand, influences ozone concentrations through dynamical and chemical changes in the atmosphere. On the other hand, increasing background ozone concentrations affect climate change because ozone is a potent greenhouse gas itself and indirectly influences the lifetime of other greenhouse gases such as methane. Other examples of linkages between air pollution and climate change are: i) SO2 contributes to acidification and also plays a role in climate change, partly off-setting the greenhouse effect due to increased amounts of sulphate aerosols in the atmosphere; ii) acidification and nitrogen deposition affect emissions of CH4 and N2O in some ecosystems; iii) increased temperatures affects nitrate leaching; iv) climate change may alter atmospheric transport patterns of air pollutants and the sensitivity of ecosystems for acidifying deposition; v) CO2 emissions are almost entirely produced by burning fossil fuels, which is also an important source of several air pollutants; vi) climate change induced stratospheric cooling is likely to delay the recovery of the stratospheric O3 layer by approximately 20 years. In turn stratospheric O3 determines tropospheric OH levels, important for air pollution, and the amount of detrimental UV radiation arriving at the earth’s surface.
Aim: to address complex effects of air pollution and climate change on forest ecosystems through an active interaction between specialists in several areas of forest sciences. The WG 7.01.01 deals with detection, monitoring and evaluation of air pollution and climate change effects on forests; the WG 7.01.02 explains physiological and biochemical processes, and develops indicators of those effects; the WG 7.01.03 addresses status and changes in forest environment from the point of view of atmospheric deposition of air pollutants, contamination of soils and nutrient cycling; the WG 7.01.04 deals with evaluation of genetic changes in forest vegetation caused by air pollution and climate change.
State of Knowledge
The impacts of air pollution and climate change on ecosystems have been issued in many studies in the last decades. The studies showed, for example, that climate change impacts are already visible e.g. on plant distribution, or that nitrogen deposition had large impacts on ecosystem composition. Impacts of climate change and air pollution on ecosystems interact in two basic ways: climate change can change the effects of exposure of ecosystems to air pollution, and vice versa; climate change can affect the sensitivity of ecosystems to specific impacts of air pollution and vice versa. The exposure of ecosystems to air pollution can change as a result of phenological changes induced by climate change (e.g. changes in the length of the growing season) as well as by changed distribution of air pollutants through changed weather patterns. Their sensitivity may change as a result of, inter alia, climate-induced changes in ecosystem vitality, soil processes and ecosystem composition.
For state of knowledge summaries please refer to the 'Publications and references' section.