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Environmental information systems
Forests play a significant role in climate by affecting the energy balance, the atmospheric composition, and the water cycle. On the other hand, climate itself affects ecological processes in forests and is decisive for forest composition. However, the overall effect is unknown.
More than the carbon cycle
Energy balance
The energy balance is the equilibrium between the amount of solar radiation absorbed by the Earth and the amount of energy radiated back into space. Forests influence this balance by absorbing solar energy through photosynthesis and reflecting some back to the atmosphere through their canopy. They also affect the distribution of heat through processes like transpiration and evaporation.
Atmospheric composition
Forests influence the mixture of gases and particles in Earth's atmosphere. They emit and absorb gases such as oxygen, carbon dioxide, methane, and biogenic volatile organic compounds (BVOCs). These emissions and absorptions can significantly impact atmospheric chemistry and climate processes, such as the greenhouse effect and the formation of air pollutants.
Water cycle
Forests influence local and regional climates, affecting precipitation patterns, evaporation rates, and overall water cycling in the ecosystem. They regulate water flows in rivers and streams by storing water in soils and gradually releasing it, contributing to stable water availability and reduced flood risks downstream.
Impacts of forest cover on climate
Forest factors that decrease temperatures:
- Evapotranspiration and cooling effect: Evapotranspiration from forest vegetation has a cooling effect, with higher rates in broadleaved forests during the growing season. Secondary organic aerosols from BVOCs may also lead to cloud formation, reflecting radiation and causing cooling.
- Carbon sequestration: Reforestation and forest growth facilitate carbon sequestration, removing CO₂ from the atmosphere. This can help mitigate global warming and contribute to cooling temperatures.
Forest factors that increase temperatures:
- Albedo influence: Forest vegetation reflect sunlight. This reflection is named albedo. Forest vegetation with low albedo absorbs radiation, contributing to warming. The extensive coniferous forest cover in northern Europe lowers the albedo, thus increasing temperatures.
- BVOC emissions and atmospheric effects: Forests emit BVOCs, which, when oxidized in the atmosphere, produce pollutants like ozone. This can lead to warming effects.