Hurricane Sandy a Taste of More Extreme Weather to Come

By Stephen Leahy

UXBRIDGE, Canada, Nov 2 2012 (IPS)

Killing nearly 200 people in the United States, Canada and the Caribbean and crippling much of New York City and surrounding areas earlier this week, Hurricane Sandy was the kind of extreme weather event scientists have long predicted will occur with global warming.

“Climate change is a reality,” said New York Governor Andrew Cuomo after Sandy swept through his state.

Sandy was twice the size of an average hurricane, and it hit the eastern coast of the United States, where sea levels have been rising the fastest, said Kevin Trenberth, senior scientist at the National Center for Atmospheric Researchin Boulder, Colorado.

“All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be,” Trenberth, an expert on extreme events, told IPS.

Whether climate change caused Hurricane Sandy is the wrong question to ask, added Trenberth. He explained that climate change helped make Hurricane Sandy more destructive than it otherwise would have been.

“This is the new normal,” Trenberth said. “It doesn’t make sense to rebuild in some regions – they’ll just be swept away again.”

Extreme Weather is the New Normal with Climate Change

Aftermath of an early tornado in Lancaster, Texas. To join thousands of others connecting the dots between climate change and extreme weather, visit ClimateDots.org.

By Stephen Leahy

CAIRNS, Australia, Apr 3, 2012 (Tierramérica)

Extreme weather is fast becoming the new normal. Canada and much of the United States experienced summer temperatures during winter this year, confirming the findings of a new report on extreme weather.

For two weeks this March most of North America baked under extraordinarily warm temperatures that melted all the snow and ice and broke 150-year-old temperature records by large margins.

Last year the U.S. endured 14 separate billion-dollar-plus weather disasters including flooding, hurricanes and tornados.

A new report from the Intergovernmental Panel on Climate Change (IPCC), released Mar. 28, provides solid evidence that record-breaking weather events are increasing in number and becoming more extreme. And if current rates of greenhouse gas emissions are maintained, these events will reach dangerous new levels over the coming century.

Since 1950 there have been many more heat waves and record warm temperatures than in previous decades.

This will only increase in future decades, as will heavier rainfall events in tropical regions and the high latitudes, according to the Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). 

The hottest day that occurs once in 20 years is likely to become a one-in-two year event by the end of the century, except in the high latitudes of the Northern hemisphere, where it is likely to happen once every five years.

The average tropical cyclone maximum wind speed is likely to increase, but the global frequency of tropical cyclones is likely to decrease or remain unchanged.

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Climate Change Could Be Worsening Effects of El Niño, La Niña

Global Warming Worsening Impacts; Creating New ENSO ‘Flavors’

By Stephen Leahy*

UXBRIDGE, Canada, Jan 11, 2011 (Tierramérica) 

The strongest La Niña weather system in 50 years has brought historic flooding to Australia and drought to Argentina, Brazil and Uruguay, driving up food prices.

Scientists now believe climate change is likely enhancing the impacts of the famous El Niño-Southern Oscillation (ENSO), a cyclical climate phenomenon that affects weather patterns around the world.

La Niña and El Niño are, respectively, the cold and warm phases of the ENSO cycle, and form part of the system that regulates heat in the eastern tropical Pacific Ocean.

Both accompany simultaneous changes in surface ocean temperature and air pressure.

In conditions defined by climatologists as “neutral,” high air pressure predominates in the eastern Pacific, while low pressure predominates in the west.

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The difference in pressure generates the trade winds, which blow east to west over the surface of the tropical Pacific, pushing the warm waters westward. The deeper, cooler waters then surface in the east, replacing the warm waters.

During episodes of La Niña, the differences in pressure are more marked, the trade winds blow more strongly, and the cold-water currents in the eastern Pacific intensify.

On the other hand, during El Niño, high surface air pressure in the western Pacific and lower pressure on the coasts of the Americas cause the trade winds to weaken or change direction, resulting in warmer water temperatures in the eastern Pacific.

“There has been a very rapid transition from El Niño to La Niña in 2010,” Kevin Trenberth, a senior climate scientist with the National Centre for Atmospheric Research (NCAR) in the central U.S. state of Colorado, told Tierramérica. Continue reading

The Yin and Yang of Climate Extremes We Will See More of

Extreme weather accounted for 76 percent of all disasters over the past 20 years. Recovery is often impossible even in the US, i.e. New Orleans 5 years after Hurricane Katrina where poor neighborhoods remain devastated

By Stephen Leahy

UXBRIDGE, Canada, Oct 13, 2010 (Tierramérica) 

The floods that affected 20 million people in Pakistan and the devastating six-week heat wave in Russia in recent months are tragic climate events — and they’re closely linked.

“The Pakistan floods and Russia heat wave were directly connected, the atmospheric science makes that clear,” Kevin Trenberth, senior scientist at the U.S. National Centre for Atmospheric Research, told Tierramérica.

A long-lasting high pressure system called a “blocking high” essentially gave western Russia a dry Mediterranean summer, which in turn shifted more- than-normal moisture into the Indian monsoon, resulting in record-breaking rainfall in northern Pakistan and India, Trenberth explained.

Wildfires burned many russian villages Aug 2010

It is difficult to determine whether climate change caused this extraordinary event, but it certainly made it much worse, according to Trenberth. “Without global warming these extremes are unlikely to have occurred,” he added.

The drought in Russian and the heavy rains in Pakistan are exactly what are expected to happen with climate change, said the expert.

“Changes in extreme weather events are the main way climate change is manifested,” he said, noting that the storms or floods that used to occur once every 200 years may now occur every 30 years.

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