ENVIRONMENT-BRAZIL: Research Contradicts Myths about Amazon

By Mario Osava Reprint | | Print |

Mario Osava

RIO DE JANEIRO, Jul 11 2002 (IPS) - The Amazon jungle curbs global warming, because it absorbs more carbon dioxide than it releases into the atmosphere, according to the preliminary results of the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), which were discussed at an international meeting this week in Brazil.

Many scientists and environmentalists see tropical forests as basically “neutral” in terms of global warming, arguing that they release the same amount of gases as they absorb, since they have reached their maximum capacity for growth, and due to deforestation and “slash-and-burn” agriculture.

On the other hand, they see forests in temperate zones, which continue growing, as a viable mechanism for absorbing greenhouse gases and mitigating the effects of climate change.

But the initial conclusions of the ongoing LBA project contradict the widespread view that the Amazon is not a carbon sink, and that the intense deforestation and forest fires actually contribute to global warming.

The LBA is studying a broad range of environmental questions in the Amazon, including trends in exploitation and preservation of the rainforest, as well as the regional and global implications of these trends for the carbon cycle, greenhouse gases, atmospheric composition, climate and ecology.

One of the project’s goals is to provide a solid foundation for the development of national, regional and global policies to ensure the sustainable management of tropical rainforests.

The Amazon jungle absorbs one ton of carbon dioxide per hectare a year, according to most of the studies presented at the LBA’s second international conference, which drew 400 scientists to the city of Manaos, the capital of the state of Amazonas in northwestern Brazil, Sunday through Wednesday.

But some researchers estimate that the Amazon absorbs more than that – as much as nine tons per hectare, conference chairman Flavio Luizao told IPS.

The Amazon jungle’s capacity to absorb carbon dioxide seems to far outweigh the emission of greenhouse gases caused by the destruction of the rainforest, but that will have to be verified through further research over the next few years, said Luizao.

However, if that conclusion is confirmed, Brazil’s position in the climate change debate will be modified. The “slash-and-burn” technique used to clear jungle for cropland was seen up to now as the country’s main source of greenhouse gases, even outstripping the use of fossil fuel.

The fires threatening the world’s greatest forest reserve turned this South American country of 162 million into one of the big environmental villains in the late 1980s.

But if the Amazon rainforest acts as a carbon sink, that is an indication that the jungle continues to grow, noted Luizao, of the National Institute of Research of the Amazonia, in Manaos.

Not only that, but the growth of the forest seems to actually be fuelled by the fires, which intensify the photosynthesis process by releasing carbon dioxide.

Another “equally important” result arising from the LBA research was the explanation of the mechanism by which the forests “recycle water,” which accounts for half of the rain that falls in the Amazon region, said Luizao.

Scientists have known for over a quarter century that the rainforests themselves produce a large part of the rainfall in the Amazon. But they did not know exactly how that occurred.

Further evidence of that phenomenon is the sharp reduction of rainfall in large deforested areas.

The condensation of humidity at low altitudes which is characteristic of tropical forests favours the falling of rain in the same area, because the clouds formed in that manner are not swept away by the wind. In deforested areas, on the other hand, clouds form at higher altitudes, and are easily carried away by the wind.

The new conclusions of the LBA project will lead to a revision of weather forecasting models in the Amazon and other tropical forest regions, said Luizao.

In the conference, researchers reported that Manaos, a city of 1.4 million, suffers air pollution levels similar to those seen in Sao Paulo, Brazil’s largest city, with a population of 10.4 million.

The negative effects of the smog were found in the river archipelago of Anavillanas, a protected ecosystem located 70 kms from Manaos.

The haphazard settlement of the Amazon region by colonists has also brought new health problems, aggravating existing diseases and spreading new viruses, noted Dr. Marcus Barros, who has been studying infectious tropical diseases for 30 years.

The LBA, the broadest scientific research project in any tropical region around the world, is aimed at “a comprehensive understanding of Amazonia,” said the project’s coordinator, Carlos Nobre, a Brazilian expert in meteorology.

The project, which got underway in 1998, consists of over 100 studies divided into seven different areas: climate physics, carbon cycle, atmospheric chemistry, hydrology, biogeochemistry, land use and human dimensions.

LBA researchers meet every two years. The project is to come to a close in 2004, at the third conference.

But the final conclusions that are to form the basis for the design of environmental and sustainable development policies will not be ready until 2008, after the data has been compiled and processed, scientific reports have been published, and an international discussion and debate of the results has taken place, said Nobre.

The United States is contributing half of the LBA’s total budget of 80 million dollars, and the European Union 20 percent.

Brazil is providing the rest of the funds. It is also in charge of running the experimental stations, and has supplied more than 250 researchers, technicians and students – nearly half of all participants. The remainder come from around 40 different countries.

The rest of the nations in the Amazon jungle region have made modest but valuable contributions which have allowed the research to extend beyond Brazil’s borders, Nobre explained.

It was on Mount Illimani, for example, in the Andes mountains near La Paz, the capital of Bolivia, that Brazilian physicist Alexandre Correia studied the effects of slash-and-burn agriculture in Brazil’s rainforests.

Smoke particles produced by forest fires are carried by the wind and end up deposited in ice in the Andes mountains. By studying various layers of ice, the researcher assessed the intensity of forest fires from 1919 to 1999, and found that the use of slash-and-burn agriculture had increased enormously over the past three decades.