Brazil – A Drying Amazon Basin

A couple of months ago I travelled through the south-western part of Amazonia writing an article about the drought that hit the region in 2010. The article was published in Stockholm Waterfront No. 2 2011 a couple of weeks ago. You can access the original article here (pdf) or read it below. You will find links and sources used in the article under my blog category Skogens framtid

Brazil – A Drying Amazon Basin

Water is scarce in many parts of the world, but maybe more surprisingly in an area where the Amazon River’s main tributaries pass through. Swedish journalist Erik Jennische went to the area to experience the recent drought himself on behalf of the Stockholm Water Front.

“We had to buy water to drink, and even to wash ourselves with for several months during the drought last year”, taxi driver Adenir said, driving through central Rio Branco, the capital of the Brazilian state of Acre in the south western part of the Amazon basin.

The drought between July and October 2010 was considered the worse ever, covering 57 per cent of the Amazon region compared to the drought of 2005, then called “the drought of a century”, which barely covered 37 per cent of the same area. The water level of Rio Negro, the Amazon main tributary, reached a record low of 13.6 metres outside Manaus in October 2010, at least four metres below average. A year earlier, when the region suffered some the worst floods ever, the river reached 29.8 metres.

Northern Mato Gross, another state covered partly by the Amazon rain forest, suffered 110 days without rain.

The consequences of the drought were severe all over. Villages and small cities along the rivers found themselves isolated for weeks. The government of the Amazon state reported having distributed 600 tonnes of food. And nearly half the municipalities along the rivers declared a state of emergency, affecting 62,000 people.

The Abuña-river, connecting Rhôndonia capital Porto Velho with Acre, and the main transportation link for fuel, lost so much of its waters that the whole state risked shortages of both fuel and food.

The worst consequences of the drought were fires caused by the hot and dry weather. In 2005 there was a threefold increase in fires compared to normal. By the end of August 2010 the Brazilian Space Research Institute had identified 41,636 fires during the first eight months of the year, an increase by 134 per cent from the year before. More than half of the fires were registered in August, when reportedly 10,000 people were affected by the fires in different parts of the country.

Further up the rivers from Acre, in the Peruvian department of Madre de Dios, the drought of 2010 was not as bad as 2005, but the consequences of the Brazilian fires were felt even there.

“The smoke from the fires in Brazil came all the way here, and together with the smoke and ashes of the local fires, many people had problems breathing, and with sour eyes,” said Josué Mercado Fuentes, engineer and specialist at the Reserva del Tambopata, one of several protected areas in the region.

The Madre de Dios is not yet as deforested as the Brazilian part of southern Amazonas, and therefore less affected by fires. But the Madre de Dios region is growing rapidly, mainly because of the illegal gold mines in the western part, and the newly inaugurated Interoceanica highway that connects The Peruvian coast with the Brazilian inland. The population has almost doubled since 1993, to approximately 120,000, not counting many of the miners that are still officially living somewhere else.

In Madre de Dios alone 25,000 ha are burned per year, adding to the deforestation caused by the illegal mining, which reached at least 150,000 ha in 2010.

“The farmers are used to burn an area relying on the moisture in the forests surrounding, retaining it from spreading. But the dryer climate in general that we have experienced since 2005 has decreased the humidity in the air, which makes the forests more vulnerable to fires. We have had several fires spreading over vast areas, burning down houses of the neighbours and other tragedies. We didn’t see that before when the virgin forests prevented the fires from spreading,” says Josué Mercado Fuentes.

Virgin rain forest can hold approximately 60-70 litres of water per square metre, a burnt forest that is resprouting may hold 40 litres, a steppe 10-12 litres and a deforested area only one litre.

The main reason fires spread is the dryer conditions caused by deforestation and the change in climate. Several models trying to predict the future climate, project an increase in the frequency and severity of droughts in the Amazon region. The most important climatological factors for the dryer climate are the sea surface temperatures in the Pacific – known as El Niño – and in the tropical north Atlantic. The warmer the water is, the dryer the climate becomes in Amazonia.

The last decades the Niño has been more influential. The droughts of 2005 and 2010 were both caused by warmer water in the Atlantic, which has a strong effect on rainfall levels in southern and western Amazonia.

In February 2011 Science Magazine published the results of a comparison of the 2005 and 2010 droughts. The report, conducted by the University of Leeds and IPAM, the Amazon Environmental Research Institute, in Brazil, concluded that the drought in 2010 covered an area 50 per cent more extensive than in 2005, and warned that “droughts co-occur with peaks of fire activity and could lead to widespread Amazon forest degradation and loss.” And, “if drought events continue, the era of intact Amazon forests buffering the increase in atmospheric carbon dioxide may have passed.”

Paulo Brando at IPAM was one of the co-authors of the report, and points out that the forest itself also produces a large proportion the rain.

“We have the Niño and the north Atlantic, but also a steady reduction of precipitation caused by deforestation. Deforestation usually causes an increase in precipitation because of more convection. When you open the forest it gets warmer. The radiation from the sun will go back to the atmosphere as heat and might increase the temperature with as much as five degrees. When the air rises it takes the moisture from the forest with it so that it falls down as rain. But then, when you get more than 30 per cent or 40 per cent of deforestation this capacity is reduced.”

This vicious circle starts with the deforestation and logging which reduces the quantity of water released by the vegetation to the atmosphere. Decrease in the volume of rain increases the possibility of fires. The fires will not only kill more trees, but also interfere in the formation of clouds and by that the possibility of rain.

The drought of 2005 has been widely studied and a WWF and Allianz report published in 2009 concluded that “the 2005 drought was an approximately 1-in-20-year event, but a 2005-like drought in Amazonia is forecast to become a 1-in-2-year event by 2025 (at 450 ppmv CO2) and a 9-in-10-year event by 2060 (at ~600 ppmv CO2) with the threshold depending on the rate of increase of CO2.” There are several reports warning that the climate change might even reduce the extent of the rainforest by one third by the end of the century.

Paulo Brando does not want to confirm these predictions.

“It is very early to say that the climate change alone can transform the forest to a system that is more similar, in terms of structure, to a savannah. But there are a lot of people testing that hypothesis right now, and it is a very important hypothesis. And most of the models do not take into account the fires and the fragmentation of the rainforest when they calculate the risk of future dieback. So that has to be investigated too.”

The importance of the Amazon to the global climate should not be underrated. The region produces 20 per cent of earth’s oxygen and has historically consumed a large part of the greenhouse gas emission. An increase in droughts and fires, and a possible future dieback of large areas will severely reduce this capacity.

Erik Jennische
Journalist based in Brasilia