Science for Brazil (Reino Unido)

Rainmakers Wanted

Publicado em 01 dezembro 2014

Tucked somewhere between the regional handicraft items and Amazonian Indian artifacts on view in Brazil’s better tourist shops, you will find the Pau de Chuva.

This “Rain Stick” looks like any other fat walking stick, until you pick it up and shake it. Then, a pleasing mellifluous rustle is heard as hundreds of tiny shells or pebbles cascade softly down its length. This souvenir is rendered even more attractive, should the saleslady hint that only powerful figures such as  a tribal pajé – or yourself – can actually make it work.

If you shake a Pau de Chuva and utter the right chants, then as night follows day, the rain will come. The  downpour  you summon will moisten the parched fields, and cover the baked, cracked mud of the empty reservoir bottoms.

Except no rain falls. Not for  you, the pajé, or anyone. Brazil may have just re-elected a president, state governors and a new house of congress. But it has not found its Rainmaker. The vacancy is still wide open.

Southern Brazil is in the middle of the worst drought for 80 years, that is causing political tension, plus social and economic turmoil. In the productive south of the country, home to the largest conurbations and its most intensive agriculture, warning lights are all on red.

Global commodity prices are moving as Brazilian harvests of coffee, cocoa and above all sugar for ethanol, dwindle. Commentators are already blaming the drought for economic downturn, for threats to public health, and world coffee prices.

For years, Brazil’s dependence on hydro rather than fossil fuels for power generation, was a source of national pride bordering on conceit. Now, empty dam reservoirs mean brownouts and policymakers are turning back to coal and oil to guarantee Brazil’s energy future.

São Paulo, the largest conurbation in South America, is down to two months’ worth of potable water in its principal reservoirs, while large swathes of its 20 million population have already experienced periods with rationing of drinking water. In a nation of sticklers for hygiene and cleanliness, Brazilians are being asked to turn off the taps. You can read an article on the effects of the drought by clicking here.

São Paulo’s angry middle class consumers joke about sending their state governor a Pau de Chuva, or invading to his house to take a good long shower. Water policy is now the subject of acrimonious dispute between federal and state administrations.

Brazil’s government has treated the crisis as a temporary problem that would likely go away with the first heavy rains of the summer, rather than a sign of potentially longer-term problems with water security.

But while it may be true that policymaking errors and delays in needed investment were compounded by attempts to sweep São Paulo’s drought problem under the carpet during recent election campaign, the real issue runs much deeper. Climate change is everywhere in the discussion.

For centuries, Brazil has been no stranger to droughts that have blighted millions of lives. But these droughts were invisible to those who made policy, generated wealth, or consumed it.

The arid Northeast of the country earned an evil reputation as the most tenacious pocket of poverty and drought-induced under-development in the western hemisphere. However, the problem – while restricted to the north – failed to generate more than cursory attention for as long as the tropical rains fell comfortingly on orange groves, ricefields and canebrakes of prosperous southern Brazil.

Now that’s suddenly changed, and scientists are trying to find out why. What they suspect is that a huge South American monsoon pattern or “sky river” of clouds that carried vast quantities humidity from north to south on a track parallel to the Andes, has undergone some secular change, shifting the  Northeastern droughts further south. Less studied than its Asian counterpart, the history and dynamics of the South American monsoon, are fast becoming a focus for policymakers, not just academics. You can read an article about this by clicking here.

Inevitably, the focus is on the Amazon rainforest. Antonio Nobre, a leading climate scientist at INPE, Brazil’s National Space Research Institute, has linked southern Brazil’s worsening drought to global warming and deforestation in the Amazon. Both are drastically reducing the release of billions of litres of water by rainforest trees, which reduces rainfall further south, he said.

For the UN Climate Change Conference held in Lima, Peru, there is no more appropriate a case study to temper what may  be any unrealistic optimism about what’s described as the best chance in a generation to tackle  climate change from a global perspective. Although the talks in Peru are aimed at bringing together 195 rich and poor countries to agree a global pact for signature in Paris in December 2015, the case of continent-sized Brazil shows how widely differing zones within countries can be affected by climate change.

Finding out why the internal dynamics of Brazilian rainfall patterns have changed so profoundly, is a huge project for meteorologists, earth scientists, and upper atmosphere experts. Which is why since 2010, teams been conducting a major “cloud census” across Brazil. These studies are, in turn, linked to Global Precipitation Measurement research carried out by NASA in the US, and JAXA in Japan.

The CHUVA Project (chuva means rain in Portuguese) on global precipitation measurement has been active since 2010 and is supported by the São Paulo Research Foundation (FAPESP) and by MEC, Brazil’s ministry of science technology and innovation. Teams used satellite as well as ground-based radar and micro-wave detection equipment, GPS locators and meteorological balloons to execute its “cloud census.”

One module in the CHUVA project investigated “megacities” and the rainfall patterns over São Paulo. (Portuguese language) data available here. Other regions studied were Alcântara (MA), Fortaleza (CE), Belém (PA), São José dos Campos (SP), Santa Maria (RS) e Manaus (AM). You can visit its website by clicking here.

Now, an important scientific publication has profiled the CHUVA Project. Entitled “Storms over Brazil” a cover article in the Bulletin of the American Meteorological Society highlights the results of the four-year study involving large-scale cloud-mapping projects in different parts of the country. It seeks to answer the question: How does convection vary across Brazil?

The lead author is Luiz A. T. Machado, from the Climate Forecasting and Weather Study Centre at Brazil’s INPE Space research Institute. You can read the article by clicking here.

The article is based on a paper by more than 20 Brazilian and US researchers explaining their appropriately named CHUVA project. It stands for Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (GPM).

The CHUVA project has published results for  five field campaigns; the sixth and last campaign will be held in Manaus in 2014. The primary scientific objective of CHUVA is to contribute to the understanding of cloud processes, which represent one of the least understood components of the weather and climate system. The five CHUVA campaigns were designed to investigate specific tropical weather regimes.

A sixth field campaign in the Manaus region carried out in early 2014, came too late for inclusion in the Journal of the American Meteorological Society article. This survey links to another major project on climate change in the Amazon basin, GOAmazon. You can read about this major international project (also sponsored by FAPESP), by clicking here. In 2017, Machado’s team plans to extend its cloud census surveys to northern Argentina.

Whatever happens at the UN talks in Lima, and whatever the outcome of the CHUVA Project, the results won’t come soon enough to solve São Paulo’s looming water crisis. Only a massive downpour to mark the end of the austral summer in March 2015 – or perhaps a thunderous shake of the Pau de Chuva – can make sure of that.

Portuguese readers can review a detailed article on the CHUVA project by Brazilian journalist Karina Toledo.