The world’s lungs (part2)

A bad old habit

For at least 10,000 years, since the ice last retreated and forests
took back the earth, people have destroyed them. In medieval
Europe an exploding population and hard-working monks
put paid to perhaps half its temperate oak and beech woods
mostly, as is usually the case, to clear space for crops. Some
100m hectares of America’s forests went in the 19th century, in
an arboreal slaughter similarly reinforced by a belief in the
godliness of thus improving�� the land. That spirit survives. It
is no coincidence that George Bush junior, one of America’s
more god-fearing presidents, relaxed by clearing brush.
In most rich countries the pressure on forests has eased; but
in many tropical ones home to around half the remaining forest,
including the planet’s green rainforest girdle the demand
for land is increasing as populations rise. In Congo, which has
more rainforest than any country except Brazil, the clearance is
mostly driven by smallholders, whose number is about to
double. Rising global demand for food and biofuels adds even
more to the heat. So will climate change. That may already be
happening in Canada, where recent warm winters have unleashed
a plague of bark beetles, and in Australia, whose forests
have been devastated by drought and forest res.
Clearing forests may enrich those who are doing it, but over
the long run it impoverishes the planet as a whole. Rainforests
are an important prop to continental water-cycles. Losing the
Amazon rainforest could reduce rainfall across the Americas,
with potentially dire consequences for farmers as far away as
Texas. By regulating run-o , trees help guarantee water-supplies
and prevent natural disasters, like landslides and oods.
Losing the rainforest would mean losing millions of species;
forests contain 80% of terrestrial biodiversity. And for those
concerned about the probable e ects of climate change, forests
contain twice as much carbon as the atmosphere, in plantmatter
and the soils they cover, and when they are razed and
their soils disturbed most is emitted. If the Amazon went up in
smoke a scenario which a bit more clearance and a bit more
warming makes conceivable it would spew