November 19, 2015, by Sue Branford
Water flow at major Brazilian power stations such as Itaipu could decline by more than 50%. Image: Herr stahlhoefer via Wikimedia Commons
Scientists warn that Brazil can expect falling hydroelectric supplies and severe crop failures by 2040 as climate change reduces rainfall and increases drought.
SÃO PAULO, 19 November, 2015 – The effects of climate change over the next 25 years could see Brazil face intense droughts that turn hydroelectric power stations in the Amazon into white elephants, and cause heavy crop losses and epidemics of dengue fever, malaria and leptospirosis.
That is the conclusion of the largest climate change study ever undertaken in Brazil – conducted by the Secretariat of Strategic Issues (SAE), a government department with ministerial status.
The objective of the SAE study (currently available only in Portuguese) was to foresee how climate change could affect the country’s main economic sectors, and to suggest strategies for increasing their resilience.
The report was published with surprising discretion, given its importance, at the end of October. No major media picked it up, and it might have passed unnoticed, but for Observatório do Clima (OC), a civil society network.
In March this year, OC reported that the two scientists co-ordinating the study – Sérgio Margulis and Natalie Unterstell – had been sacked after the appointment of a Harvard philosopher, Roberto Mangabeira Unger, as SAE boss, although almost a dozen groups continued working on the study. The firings were interpreted by OC as a demonstration of the low ranking given to climate change in the government’s priorities.
The new study brings together two climate models – broad brush data from the UN’s Intergovernmental Panel on Climate Change, and more detailed information on South America from Brazil’s National Institute for Space Research (INPE).
With this data, the study produces two simulations: one, called RCP 8.5, assumes that the world carries on as now, doing little to keep temperature rise below the internationally-agreed threshold of 2°C; the other, RCP 4.5, assumes efforts to control emissions, but not energetically enough to keep global warming down to 2°C.
Under both scenarios, Brazil becomes hotter and drier overall, though there are regional variations, with the south receiving more rain while the Amazon and the north-east get considerably less, particularly in the summer.
One of the report’s studies used rainfall predictions to construct a model to assess the impact on Brazil’s hydroelectric output, which produces about 78% of its electricity.
A scientist from the National Institute of Amazonian Research (INPA) has shown that hydropower stations have their emissions problems, producing large amounts of the two principal greenhouse gases, carbon dioxide and methane – sometimes in greater quantities than the emissions from fossil fuel power plants.
The scientists in the SAE study looked not only at projected rainfall as climate change intensifies, but also at the predicted impact on river flows, because energy generation at hydroelectric power plants depends on how much water is flowing through them.
Results suggest that the flows at the country’s four largest power stations – Itaipu, Furnas, Sobradinho and Tucuruí – will decline between 38% (RCP 4.5) and 57% (RCP 8.5). Brazil has suffered serious water shortages in the last three years, so this projection prompts considerable concern.
Brazil has already exploited most of its hydro-generation potential in the rest of the country, so the government expects the Amazon basin to play a starring role in the future, with no fewer than 30 of the 48 planned dams destined for the Amazon rainforest. Some have already been built, and the study suggests that all will be seriously affected.
One conclusion seems certain: Brazil cannot plan
for the future on the basis of past assumptions that
the climate will essentially remain the same
The flow for the Santo Antônio dam on the Madeira river, which flows into the Amazon basin from Bolivia, is expected to fall by between 40% (RCP 4.5) and 65% (RCP 8.5). And the flow of the Xingu river in eastern Amazonia, which will feed the giant Belo Monte dam, now nearing completion, will fall by from 25% (RCP 4.5) to 55% (RCP 8.5).
There are already grave concerns about Belo Monte’s financial viability, as it is expected to operate at its full capacity for only two months in the year, generating just 4,500 megawatts (MW) out of its installed capacity of 11,233 MW. Further reductions in the flow could well make the dam financially unviable.
The outlay (at least US$18 billion) and the extensive damage already inflicted on biodiversity and indigenous and traditional people would both have been for nothing.
Unless the government has a rethink, the same could happen elsewhere in the Amazon. The simulations suggest that the flow for the Sāo Luís dam planned for the Tapajós river could decline from between 20% (RCP 4.5) to 30% (RCP 8.5).
Unlike Sāo Luís, most new power plants planned for the Amazon use run-of-the-river schemes, meaning they use river flows without the construction of large reservoirs. Their electricity generation will rely directly on the amount of water flowing in the river at any given time, so the amount of energy generated will be seriously reduced if the dry season gets longer.
Brazil could fall into a vicious cycle: the more dams built in the Amazon, the greater the deforestation, which adds to climate change, which in turn reduces the efficiency of the dams.
The report also looks at the impact of climate change on agriculture, and concludes that some of the country’s main crops could suffer a serious decline in the areas already under cultivation – corn (28%), beans (26%) and rice (24%).
Worst affected would be the country’s main export crop, soybeans, declining by up to 39%. This would mean significant financial losses, since the crop currently brings in US$ 20 billion in export earnings annually.
The report relies on simulations, which, of course, can always be wrong. But one conclusion seems certain: Brazil cannot plan for the future on the basis of past assumptions that the climate will essentially remain the same.
As Roberto Schaeffer, a scientist involved in the study, told OC: “We can’t do this any more. The future will not necessarily repeat the past.” – Climate News Network
Sue Branford, a journalist, is managing editor of the Latin America Bureau UK website.