Deforestation and forest degradation are both a cause and a result of climate change. Plants absorb carbon dioxide and use it to grow, but when they decay or burn the carbon dioxide is released again. Decaying plants also produce methane, a greenhouse gas more potent than carbon dioxide.
So deforestation and forest degradation are doubly damaging, because
greenhouse gasses are released (e.g. through forest fires, or using the
cut trees as firewood), while at the same time the number of carbon
dioxide absorbing trees are reduced. Thirty percent of the carbon
dioxide added to the atmosphere over the past 150 years is thought to
come from deforestation, but this is a small amount compared to what is
still stored in forests. The Canadian and Russian boreal forests alone
hold 40 percent of the world's carbon stocks.
How climate change is hurting forests
Changes in temperature ranges and precipitation can harm forests.
Droughts and forest fires are expected to increase due to climate
change. Forest fires can be a normal part of forests - they clear dense
brush and are part of some species lifecycle. However, forests
over stressed by human activity and drought can also be devastated by
them. There are already indications that the Amazon is drying
out, which could lead to a dangerous feedback of fires and
desertification.
Invasive insect species may also damage forest health. Insects play a
role in boreal ecology - they decompose litter, supply food for birds
and small animals, and eliminate diseased trees. But insect attacks are
likely to increase in frequency and intensity as established forests
succumb to the physiological stress associated with warmer, drier
conditions. As the Arctic warms, some invasive insect species, which
the colder climate normally helps hold in check, are already increasing
in population.
Replanting and sustainable forestry
It's worth noting that proper sustainable forestry practices do not
cause a net increase of carbon dioxide in the atmosphere because a new
tree is grown for every one cut down. By contrast, clear cutting and
converting forestland into to urban areas has a very high negative
impact - because the forest is destroyed and replaced with heat
absorbing pavement and buildings.
Obviously, re-forestation, sustainable logging and protecting ancient
forests are essential to not increase the pace of climate change
further - so long as these forests are not destroyed later (by future
logging, forest fires, etc.).
However, to prevent dangerous human induced climate change, we need to
address the main cause - the burning of fossil fuels and the release of
industrial greenhouse gasses into the atmosphere.
Also see the
Greenpeace forests campaign.
Help protect the world's ancient forests by buying only Forest
Stewardship Council (FSC) certified wood, and products with
post-consumer recycled content. You'll be saving vital habitat,
and doing good by the climate at the same time.
More information:
Amazon under threat
Kyoto pitfalls
Greenpeace forest home
wood shopping guide (Flash with audio)
Greenpeace
paper buying guide