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Scientists are starting to link natural disasters to rising greenhouse gases.
La Nina and its warm-water counterpart, El Nino, are part of a natural pattern of ocean currents and atmospheric winds that redistribute heat by moving it from one part of the world to another. Even as La Nina and El Nino influence the overall climate, much like organs in a body, they may remain vulnerable to system-wide shocks, said Paul Mayewski, director of the Climate Change Institute at The University of Maine.
So far scientists have found no definitive link between rising greenhouse gases and changes to El Nino and La Nina events. But Mayewski thinks that might be changing.
“This is a naturally occurring phenomenon,” Mayewski said. “That doesn’t mean it can’t be impacted by humans.”
He is investigating whether greenhouse gases may have so disturbed the balance of heat that natural patterns, like El Nino and La Nina, may begin to speed up and intensify.
“We may very well be changing this El Nino-La Nina system much faster and more radically,” Mayewski said. “It’s a naturally occurring system that we may be giving a lot more push to.”
And, if he’s right, that could mean even less stable, more extreme weather in the foreseeable future.
For some agencies working to help countries prevent and recover from natural disasters, there’s no question that they’re getting worse.
“There was never any doubt in our mind that, in reality, the frequency and severity and number of people that were affected kept increasing,” said Margareta Wahlstrom, the United Nations' assistant secretary general for disaster risk reduction.
In an increasingly urbanized world, people, goods and infrastructure are concentrated, meaning that each natural disaster has the potential to cause an unprecedented amount of damage.
“The losses are increasing very rapidly,” Wahlstrom said. “Today is decision time. We know what the risks are. We can see the trends.”
With the effects of global warming already manifest, Wahlstrom said, countries need to improve disaster preparation even as they negotiate to cut emissions that cause the problem in the first place.
For a country such as Brazil, that means developing early warning systems for heavy rains and better evacuation plans, as well as moving people out of the most vulnerable neighborhoods. The government has pledged to do just that in response to the recent tragedies.
Tackling the problem after the fact is devastatingly expensive. Officials in cities destroyed by the floods here say it will take a decade and hundreds of millions of dollars to rebuild. And a recent study predicts that a warming climate could cost Latin American countries about 1 percent of their GDP every year from now until 2100.
While natural disasters tend to be more deadly in developing countries, this last year has shown extreme weather can strike planet-wide.
“The attitude that many of us probably have lived with for decades, because we’ve lived in fairly safe countries, is that disasters are something that happens to others,” Wahlstrom said. “That is no longer viable.”