The Effect of Forests on Climate
From: Andy Soos, ENN.com
Once there were vast
forests covering North America and Europe. What happens to the climate if they
were returned? Planting trees in an area where there are no trees now, can
reduce the effect of climate change by cooling temperate regions finds a study
in BioMed Central's open access journal Carbon Balance and Management.
Tree forests cover
approximately 9.4 percent of the Earth's surface (or 30 percent of total land
area), though they once covered much more (about 50 percent of total land
area). A forest is an area with a high density of trees. As with cities,
depending on various cultural definitions, what is considered a forest may vary
significantly in size and have different classifications according to how and
of what the forest is composed.
Climate change is
projected to lead to summer droughts and winter floods across Europe. Using
REMO, the regional climate model of the Max Planck Institute for Meteorology,
researchers tested what would happen to climate change in 100 years if land
currently covered in non-forest vegetation was converted into deciduous forest.
This equates to more than a doubling of forest in Poland, Czech Republic,
Denmark, Northern Ukraine, Northern Germany and France.
The large leaf area and
low aerodynamic resistance of these types of trees lends itself to enhanced
evapotranspiration compared to other vegetation, cooling the surrounding air,
and leading to cooler surface temperatures. The model indicates that in the
northern part of central Europe and Ukraine afforestation results in 0.3-0.5C
decrease in temperature and 10-15% more summer rain by 2071-2090.
Large contiguous forest
blocks can have distinctive biogeophysical effect on the climate on regional
and local scale. Results of this case study with a hypothetical land cover
change can contribute to the assessment of the role of forests in adapting the
world to climate change. Thus they can build an important basis of the future
forest policy.
Reforestation of this
magnitude is unlikely to occur because the land in question is often in use by
humans for agriculture or habitat. But i does point out the net positive
effect of of forests on climate and allows a prediction of what might be doable
to some degree of magnitude.
For further information
see Reforestation.