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New climate change models predict a heavy impact from global warming on Brazil's biodiversity, agriculture and health, reports Helen Mendes.

Like other developing countries, Brazil is highly vulnerable to climate change: the pressures of poverty make it harder for its population to recover from natural disasters. And these are predicted to be on the rise, with climate scientists saying global warming will increase the frequency of extreme climatic events such as floods and drought. The message is that major efforts will be needed to adapt to future changes.

A useful starting point is climate models, used to predict likely changes in specific regions as the world warms. Computer programs that simulate the climate system and offer climate projections, these models process information such as temperature, winds, the way clouds form and precipitation falls, and the amount of greenhouse gases in the atmosphere.

But models sophisticated enough to be useful in preparing for those changes have not surfaced in Brazil — until now.

Change magnified

José Marengo, a researcher at the Center for Weather Forecast and Climate Studies has been evaluating climate change scenarios for Brazil using the country's first-ever regional models, which allow more detail than the global versions.

Climate models show the surface of the Earth under a three-dimensional grid. In a global model, each grid cell covers hundreds of kilometres. But climate in specific regions is affected by atmospheric circulations and topographical features — such as mountains or valleys — on scales smaller than the 300 kilometre grid cells of global models.

Grid cells in regional models, however, cover just 40 kilometres each and so can provide specific information on, for instance, how a sea breeze can change or how often it rains in a city.

"The regional model is like a magnifying glass," says Marengo. He says regional climate models will be useful to "define public policies, and for different sectors of society to make necessary adaptations".

"The purpose is to deliver scenarios to specialists on agriculture, health and water resources, so that they can analyse the effects of climate changes and point out solutions," says Marengo. For instance, in Brazil a drier climate could mean people are more susceptible to respiratory diseases, whereas a warmer climate could trigger a rise in cases of dengue fever.

In other parts of the world, regional models are already used to assess the impact of global warming on temperature extremes, water resources, agriculture and forest fires. Regional models of Argentina, Chile and Peru, for example, show how the melting of ice caps in the Andes is accelerating and the impact this will have on cities. Whilst there will be overflowing lakes and flooding in some areas, others could see their water supply decrease. Lima, for instance, has a desert soil and depends on the ice caps for water during six months of the year.

Heat and dust

In Brazil, Marengo's models predict that climate change is most likely to affect agriculture, and natural ecosystems such as the Amazon rainforest and Pantanal wetlands.

Even if measures are taken to tackle global warming and the Kyoto Protocol achieves its goals, Marengo predicts that between 2070 and 2100 there will be an increase in the annual average temperature of 2–3 degrees Celsius around nearly the entire Brazilian coast and a substantial portion of the rest of the country.

Temperature increases
predicted for Brazil by 
2100 (orange = 4;
red = 6 degrees
Celsius) due to climate

An area of the Amazonas state the size of the United Kingdom may see increases of up to six degrees.

If nothing is done to halt global warming, the models show the temperature in most of the country rising 4–6 degrees by 2100. Major increases would occur in a small area of north Amazonas, where an eight degree rise is predicted.

In the Amazon rainforest, Marengo's models reveal warming as well as delays in the rainy season's arrival. The region would become 5–15 per cent drier at best, and 15–20 per cent drier in the worst-case scenario. This would affect water flow, not only in the Amazon river but in all other rivers in the region, and would have a major impact on river transport and hydroelectric energy generation. It would also have an impact on public health, as dry weather increases the incidence of respiratory diseases. The risk of forest fires would also increase.

Predictions based on the models suggest that, even if preventative measures are taken, rain will decrease in the Amazon and the Pantanal, as well as in Brazil's northeast, a good part of which is already semi-arid. Global models have previously indicated the likelihood of more frequent extreme climate events, such as stronger, shorter rains, or longer droughts that could turn northeast Brazil into a desert.

But rains are predicted to increase by five per cent in Brazil's southern and southeastern regions and in parts of Argentina, brought by winds from the Atlantic Ocean. These rains, however, will be intense and concentrated into a few days, and so won't be copious enough to fill water reservoirs at hydroelectric power stations. This will be problematic, as the higher temperatures bring increased energy demands for air-conditioning.

Climate changes will have a massive impact on agriculture, and may make growing crops such as soya beans, corn and coffee — some of Brazil's most important exports — unfeasible in some areas. Brazil's Agricultural Research Corporation used Marengo's projections to ascertain the future for these crops and found that some of the plantations will have to move south as the heat rises.

Farmers will have to adapt, either by creating seeds that can survive in a warmer climate, or by cultivating species that resist heat and dry weather.

The human factor

One Brazilian group is also looking at the social impact of global warming. A team at Brazil's National School of Public Health at the Oswaldo Cruz Foundation (Fiocruz) have developed a method to evaluate the potential damage to public health from climate change. Fiocruz is the first organisation in Brazil to consider these two issues together.

The team's General Vulnerability Index (IVG) is based on the Human Development Index, which was developed by the UN Development Programme to evaluate social welfare in different countries. The IVG takes into account socioeconomic and epidemiological factors together with changes in climate.

The index's socioeconomic component uses data related to demographic density, urbanisation, income, schooling and infant mortality.

The epidemiological component considers rates of mortality from six infectious diseases (cholera, malaria, dengue fever, leishmaniasis, leptospirosis and hantavirosis), all of which are sensitive to variations in climate. It also considers the costs to the healthcare system and the expenditure on technology needed to control diseases.

The climate component looks at the frequency of events such as droughts and floods over the past 40 years.

Using the index, the Fiocruz team led by Ulisses Confalonieri spent three years analysing data from every state in Brazil.

They found that the northeastern region is the most sensitive to variations in climate because of a combination of poverty, disease and cyclical droughts. The state of Alagoas would fare worst — a consequence of being the poorest and most densely populated, with little sanitation, a high infant mortality rate, and the highest number of cholera cases in Brazil.

Confalonieri hopes the team's results will lead to new public policies on healthcare, such as disease control.

But he says that Brazil's healthcare must be improved irrespective of new risks from climate change.