4. Conclusions
Global circulation models used by the
Intergovernmental Panel on Climate Change
(IPCC) indicate precipitation declines in Brazil
that can be expected to decrease the yields of silvicultural
plantations. Simulated climate experiments
reported by the IPCC with CO2 gradually
increased to ``around the time of CO2 doubling''
produce June±July±August (dry season) precipitation
reductions corresponding to approximately
34% in Amazonia, 39% in Southern Brazil, and
61% in the Northeast. Taking as examples rainfall
reductions of 5, 10, 25 and 50%, plantation
area requirements are calculated to increase up
to 38% over those without climatic change,
which would bring the total plantation area by
2050 to 4.5 times the 1991 area.