They detected an intensification in the
forest’s decline. This decline was consistent with lower rainfall,
poorer water storage below the canopy and a gradual change in the
composition of species.
“It is important to understand these
changes because most climate models predict tropical forests may be
under stress due to increasing severe water shortages in a warmer and
drier 21st century climate,” said Liming Zhou, of Albany State
University of New York. But other factors could accelerate this
“browning” of one of the world’s greatest rainforests.
Half as hot again
A team from the Catholic University of
Louvain in Belgium - also known in Belgium’s other language as KU Leuven
- predicts in the Journal of Climate that explosive population growth
and inefficient agricultural practices are likely to make things a great
deal hotter for the region and a great deal worse for the rainforest.
By 2050, according to their computer
models, Central Africa will be on average 1.4°C hotter than it is today
just because of greenhouse gas emissions. And the steady destruction of
the forest will add an extra 0.7°C to that figure.
Temperature increases on such a scale will
harm plant and animal species and even bring about some extinction.
Where the forests have been cleared, there will be increased levels of
evaporation, and consequent rises in temperature.
Across the Atlantic, things also look
bleak for the Amazon rainforest. Paulo Brando of the Amazon
Environmental Research Institute in Brazil and colleagues from the US
report in the Proceedings of the National Academy of Sciences that the
piecemeal clearing of the rainforest, along with drought, has begun to
create “tinderbox” conditions and an ever more destructive cycle of
Over the course of eight years, in one of
the longest-running experiments of its kind, the researchers burned
50-hectare plots of forest in the south-eastern Amazon, a region
vulnerable to climate change. They compared the tree deaths each year to
measure the impact of drought on fire intensity.
“Drought causes more intense and
widespread fires,” said Dr Brando. “Four times more adult trees were
killed by fire during a drought year, which means that there was also
more carbon dioxide released into the atmosphere, more tree species loss
and a greater likelihood of grasses invading the forest.”
This research, too, was backed up by
satellite observation. In 2007, a year of drought, fires in south-east
Amazonia burned 10 times more forest than in an average year - an area
equivalent to a million soccer fields, according to Douglas Morton of
the US space agency Nasa, a co-author.
Climate change is expected to bring
shorter, more intense rainy seasons and longer dry seasons in the
region. Michael Coe of Woods Hole Research Center, another author, said
“We tend to think only about average conditions, but it is the
non-average conditions we have to worry about.”
Climate News Network