sábado, 7 de janeiro de 2012

Como o Brasil, toda a América Latina passa por sérios problemas climáticos

Latin America Battling Wildfires, Floods, Droughts

Helicopters fight a massive forest fire affecting the commune of Quillon, in southern Chile's Bio Bio region, on January 3, 2012. (Getty)

CHIA, Colombia -- From Chile to Colombia to Mexico, Latin America has been battered recently by wildfires, floods and droughts.

For many witnessing the extreme weather in the region and around the world, the question that comes up again and again is whether climate change is playing a role. The response from experts: Probably.

While leading climate scientists are unable to pin any single flood or heat wave solely on climate change, experts say the number of extreme weather events is increasing worldwide and the evidence suggests global warming is having an impact.

Wildfires are raging in Chile during an atypical heat wave, and northern Mexico is suffering from its worst drought in 70 years of record-keeping. A second straight season of heavy rains in Colombia killed at least 182 people, destroyed more than 1,200 homes and caused an estimated $2 billion in damage in the past four months.

Researchers predict more wild, unusual weather in the coming years, and they say Latin America is especially vulnerable because deforestation and sprawling construction have made the region more susceptible to flooding and landslides.

At a rose farm in the Colombian town of Chia, workers say floodwaters covered fields of roses last month for the second time in less than a year, leaving damaged greenhouses and a wasteland of shriveled flowers.

"Never in the history of this farm – and it's a business with 30 years in the market – have we ever had any such problem," said Javier Castellanos, the farm's manager, who estimates the damage at more than $6 million after floods in April and December.

He suspects climate change has been intensifying the rainstorms.

While experts say the cyclical cooling of the Pacific Ocean known as La Nina is a big factor in the weather, some also say climate change is likely making some of the severe weather more pronounced than it otherwise would be.
"We're seeing an increase in extremes of high temperatures, an increase in extremes of heavy precipitation, an increase in the length and severity of droughts," said Chris Field, director of the Carnegie Institution's Department of Global Ecology at Stanford University.

"It is not yet scientifically possible to say with confidence that any single event is a consequence of human-caused climate change, but we have confidence in both the general trend and in the fingerprint of human activity," Field said.
Unusual weather has been plentiful in the past year, from floods in Thailand to drought in Texas.

In Latin America, a severe drought is hitting Argentina, harming key export crops such as soybeans and corn and leaving cattle with little to feed on. Unusually dry weather and high temperatures have made forest fires much harder to control in usually wet areas of southern Chile.

In Bolivia, seasonal rains that used to come in September instead arrived in mid-December after a record heat wave. Puerto Rico had its second wettest year in more than a century of record-keeping.

Some experts stress that the dominant factor in much of the weather is currently La Nina. Like El Nino, which in contrast involves warmer Pacific waters, it's associated with weather changes throughout Latin America and elsewhere.

"It would be very risky scientifically speaking to attribute this historic record (drought) in the case of Mexico to climate change," said Rodney Martinez, scientific coordinator of the International Research Center on El Nino in Ecuador. "In the case of Colombia ... what's happened corresponds perfectly with a natural event like La Nina."

One of the questions now being researched by scientists is how climate changes may affect the El Nino/La Nina cycle.

Jeff Masters, director of meteorology for the website Weather Underground, said it's unlikely so many extremes would naturally occur in such a short period. He cited two major droughts in the Amazon in 2005 and 2010, and Colombia's 2010 rains, which were the heaviest in at least 42 years.

"I think you really have to point the finger at human-caused climate change as having tipped the scales to make previously unprecedented weather events more possible, and multiple unprecedented weather events like we're seeing," Masters said. "There is so much regular variation in the weather, and it's hard to pick out the signal from the noise. But the signal's sure getting pretty strong now."

Field likened the influence of global warming to talking on a cell phone while driving. "There are always traffic accidents, but if you throw people talking on cell phones in the mix, you increase the probability," Field said. "The role of climate change and weather-related extremes is similar."

Michael Mann, director of the Earth System Science Center at Penn State University, said a warming climate has become "part of the fabric – the background state – in which all weather happens."

"The overall character of weather events, with each passing year, is being more and more influenced by human-caused climate change," Mann said.

In Colombia, the latest floods between September and December set off mudslides and forced hundreds of thousands of people to temporarily evacuate their homes.

At the rose farm in Chia, north of Bogota, flowers in dozens of greenhouses were destroyed by the overflowing Bogota River, and workers had to use pumps to drain the land afterward. The farm's workers say they've never seen anything like it.

Experts note that Colombia has suffered floods during previous La Ninas and that regardless of the causes behind the weather, better planning for intense storms is vital.

"We must invest in reducing our vulnerability," said Omar-Dario Cardona, a civil engineer and professor of disaster risk management at the National University of Colombia.

He said that means not rebuilding in areas that have suffered flood damage and reducing exposure by relocating at-risk homes, crops and infrastructure.

The clearing of forests and destruction of wetlands in Colombia also have worsened floods because less rainwater is captured and it instead runs directly into rivers, said Manuel Rodriguez Becerra, a former Colombian environment minister and a professor at the University of the Andes in Bogota.

If the number of floods and droughts keep increasing as researchers predict, Rodriguez said, "there are areas that are really going to suffer a lot."
Ian James reported from Caracas, Venezuela. AP writers Carlos Valdez in Bolivia, Ben Fox in Puerto Rico, Michael Warren in Argentina and Stan Lehman in Brazil contributed to this report, as well as AP Video Journalist Haven Daley in San Francisco and AP Science Writer Seth Borenstein in Washington.

Fonte: Huffington Post

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