 |
|
|
The Amazon Jungle as Vast Savanna |
|
By Mario Osava* - IPS/IFEJ*
Global
warming will broaden the effects of deforestation, which could turn
60 percent of the Amazon forest into grassland in this century,
say scientists from the Intergovernmental Panel on Climate Change.
RIO DE JANEIRO, Apr 9 (IPS/IFEJ) - An Amazon
region that is less lush, where forest is replaced by grasslands,
is the image drawn by the latest scientific reports in which meteorologists
are taking the lead, going beyond even the direst warning of ecologists.
If current trends continue, deforestation, which in the last 30
years claimed nearly 600,000 square kilometers in the Brazilian
Amazon alone -- an area equivalent to Germany and Italy combined
-- will have destroyed more than 30 percent of the Amazon jungles
by 2050, according to the latest report from the Intergovernmental
Panel on Climate Change (IPCC).
This process could "convert into savanna" as much as 60 percent
of the Amazon region, says a 2003 study by Carlos Nobre and Marcos
Oyama, of Brazil's National Institute of Space Research (INPE).
Global warming "will greatly amplify" those effects, says the IPCC
in the second volume of its 2007 report, "Impacts, Adaptation and
Vulnerability", released Apr. 6 in Brussels.
The IPCC report, of which Nobre was one of the contributing authors,
emphasizes the urgency of containing the deforestation of the Amazon,
a process that is responsible for 75 percent of Brazil's climate-changing
greenhouse gas emissions.
"Brazil can only win with this," because it would protect enormous
future wealth and would give Brazil a leadership role in the climate
change debate, said Antonio Ocular Mainz in an interview. He is
the executive manager of the Large-Scale Biosphere-Atmosphere Experiment
in the Amazon, a research initiative involving Brazilian and foreign
scientists.
Average temperatures in the Amazon region could rise an average
of 8 degrees Celsius by the end of the century if the climate change
factors continue, says meteorologist José Antonio Marengo, in a
report presented to Brazil's Environment Ministry in February.
In some areas, the average temperature could increase as much as
12 degrees, said Philip Fearnside, a U.S. ecologist and Amazon expert
who has worked for the last 30 years for Brazil's National Institute
for Amazonian Research, INPA. This will happen if nothing is done
to contain deforestation or global climate change, he added.
Warmer temperatures mean that trees consume more water to carry
out photosynthesis, which is why it has such a big effect on forests.
But climate change's great threat to the Amazon is that it could
generate a permanent El Niño phenomenon (a now cyclical warming
of surface waters in the Pacific Ocean), manifested in more heat
and longer periods of scant rains north of the Amazon River, says
Fearnside, also an author of the IPCC report.
That was the case in 1997-1998, when drought triggered devastating
fires in the northern Brazilian state of Roraima. And in 2006, a
moderate El Niño greatly curbed rainfall along the Rio Negro, a
main tributary of the Amazon River.
Global warming so far -- moderate compared to what scientists say
is expected to come -- has been accompanied by an increased frequency
of El Niño since 1976.
El Niño will be "more frequent and more intense" if humans don't
take action to mitigate the greenhouse effect, Fearnside said in
an interview for this article.
To the south of the Amazon River drought is also a problem, related
to the warming of waters in the Atlantic Ocean. In 2005 there were
uncontrollable fires in Acre state, which is carrying out a much-lauded
forest conservation policy. Fires are the big factor in the conversion
of forests into savanna.
Another reason for being "on the verge of the 'savannization' of
the Amazon" is the existence of parts prone to that process, like
Santarém, in the region's east, with tropical forests but rainfall
equivalent to that of Brasilia, which is located in the country's
Cerrado, a savanna biome, Fearnside explained.
An isolated voice has spoken out against such dire predictions.
Respected Brazilian geographer, Aziz Ab'Saber, 83, says that just
the opposite will occur: there will be a greater density of forests
in the Amazon and other biomes as a result of global warming.
The heat will increase evaporation of waters from the Atlantic and
this humidity will reach the South American continent, increasing
rainfall, Ab'Saber has said in many interviews given since the publication
of the first volume of the IPCC report in February.
The expert, who applied the "refuge theory" to explain the formation
of the Amazon forests, points out that six thousand years ago the
planet went through a "climatic optimum", with a warming phase that
raised ocean levels after the ice age and caused more rains and
the "re-tropicalization" of Brazil.
The warm currents of the Atlantic will continue, and they were not
taken into consideration by the IPCC, says Ab'Saber.
Other researchers avoid controversy, but note that the current scientific
studies are based on complex mathematical models that include a
wide array of variables, such as past experience and ocean currents.
"The results are consistent" and perhaps provide a better assessment
of the water cycle, with more recent data and which Ab'Saber hasn't
taken into account, said INPE researcher Gilvan Sampaio.
About half of the Amazon region's rainfall is the product of re-evaporation
from the forests themselves. Deforestation reduces the amount of
water vapor, and the effects would also be felt in central-southern
Brazil and parts of Argentina, Bolivia and Paraguay, said Sampaio.
"At least 30 percent of the rains in southeast Brazil come from
the Amazon," where humid winds move from the east that the Andes
Mountains push southward, he explained.
But the question of Amazon rainfall still poses uncertainties, said
Manzi. Most of the assessments also indicate more rains in the western
Amazon, near the Andes, and therefore denser forests.
Meanwhile, in the eastern Amazon there are doubts about predictions
for scarce rains. In general, the mathematical models point to "drier
climate than the reality", but they correctly predict the evolution,
he acknowledged.
We can't rule out less tragic effects than the ones predicted, but
it depends on whether measures are taken immediately, such as a
dramatic reduction in Amazon deforestation, Manzi added.
Since the 1970s, extreme climate phenomena have intensified, like
the 2005 drought in the southwest Amazon.
Fearnside underscored the synergy between droughts triggered by
El Niño and the warming of the Atlantic, destruction of forests
from logging and the expansion of agriculture, and fires caused
by human activity and drought, which tend to claim the biggest trees,
vital for maintaining the forest microclimate.
* (This story is part of a series of features
on sustainable development by IPS-Inter Press Service and IFEJ -
International Federation of Environmental Journalists.) |
