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Deforestation causing São Paulo drought

Deforestation near São Paulo, Brazil Deforestation near São Paulo, Brazil AFNR
05 Feb
2015
Brazil possesses 12 per cent of the world’s freshwater, and yet São Paulo – the biggest and richest city in South America – is suffering from severe drought with deforestation getting the blame

Water rationing. Power cuts. Crop slumps. The past twelve months has seen Brazil being hit harder and harder by the effects of drought, as first São Paulo, then other regions of the country, struggle to cope with dwindling supplies of water but an immense demand. Local reservoirs are running at historic lows, such as the Cantareira system – which supplies water to over a quarter of the 20 million São Paulo residents and is currently down to only five per cent of its 264 billion gallon capacity. A ‘five-days-off, two-days-on’ rationing system is currently being proposed as a solution to prevent the reservoir running completely dry.

The proposed reasons for the drought are plentiful. Authorities have come under fire for their failure to upgrade and maintain the necessary infrastructure to stop water being stolen or wasted in transit, with as much as 37 per cent of tap water failing to make it successfully to the people who need it, according to recent government reports.

There is also the exacerbation of Brazil’s general water problems caused by population concentration around the coasts, as well as the role that wet and dry seasons play in creating seasonal variability, which places more pressure on governments to capture and store large volumes of water during periods of high rainfall.

BrazilImage: World Resources Institute

However, another explanation which has received increasing attention surrounds how the impact of Amazonian deforestation could be altering the relationship between the rainforest and the climate in Brazil’s ecosystem. As covered by Geographical, deforestation in the Amazon totalled 4,848 km2 between August 2013 and July 2014. However, despite the implementation of a much-lauded soy moratorium, and ever-increasing levels of surveillance across the rainforest, there remains a significant challenge for NGOs and the Brazilian authorities to halt the continuing deforestation, and the subsequent effect it is having on both the ecosystem and on the lives of people in Brazil’s cities.

‘The Amazon rainforest takes water from the trees, rivers and soil and turns it into clouds known as ‘flying rivers’,’ Richard George, forest campaigner for Greenpeace UK, explains to Geographical. ‘These transport water vapour from the centre of Brazil to fall as rain on coastal areas. But as the forest has been destroyed, the flying rivers are disappearing. If the flying rivers disappear for good, many Brazilian states, including the main export states of Pará and Mato Grosso, would be transformed into arid deserts.’

The scale of transformation which would accompany the disappearance of the Amazon’s  flying rivers is outlined in a recent report by Professor Antonio Nobre, researcher at Brazil’s National Institute for Space Research (INPE) and at the National Institute of Amazonian Research (INPA), entitled The Future Climate of Amazonia, in which he paints a vivid picture of how the climate of Brazil and surrounding South America is likely to be impacted by current trends in deforestation. Top of the list is the aforementioned drought, as moisture – no longer trapped by rainforest vegetation – rapidly evaporates, leading to what is described as the ‘savannisation’ of the Amazon basin.

Flying rivers transport water vapour from the centre of Brazil to fall as rain on coastal areas. But as the forest has been destroyed, the flying rivers are disappearing

‘The models that simulate complete deforestation of the Amazon predict a climate warming of 0.1–3.8°C (average of 1.9°C) and a rainfall reduction of around 140–640 mm per year (average of 324 mm/ year, or a decrease of 10–15 per cent),’ he writes. ‘Many of the model projections for the consequences of deforestation have already been observed, especially the expansion of the dry season. However, these virtual experiments indicated that a prolonged dry season would occur after the complete destruction of the Amazon forest, but in fact it is already being observed after the clearcutting of just under 19 per cent of the forest. Therefore, these models appear to underestimate the negative consequences of deforestation in simulated scenarios.’

This unanticipated impact of even partial rainforest deforestation on causing drought in Brazil’s cities – as São Paulo has experienced over the past year – has drawn a direct link between the state of the Amazon rainforest, and the safety and well-being of the Brazilian people. While this has galvanised many environmentalists into demanding action from the Brazilian government, there is also the possibility that domestic businesses will have a more influential voice in how the authorities should respond to the continuing drought conditions.

‘Ironically, the drought is already affecting Brazil’s agribusiness sector, a major cause of forest destruction in the Amazon,’ continues George. ‘The risk, of course, is that instead of putting pressure on the government to stop deforestation, Brazil’s powerful agribusiness lobby will demand the right to clear even more forest to make up for the declining yields.’

Nobre’s report concludes with a five-point plan to prevent further destruction to the Amazon; spreading rainforest education, ending deforestation, ending fire-clearing techniques, encouraging rainforest regeneration, and forcing world leaders to act to prevent potential crisis.

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