U.S. Heat Waves to Intensify From New York to Los Angeles

Heat waves are likely to intensify and last longer from California to the U.S. East Coast as global warming takes hold, according to the United Nations’s most comprehensive report on extreme weather events.

Average wind speeds of hurricanes are likely to increase, with projected sea level rises compounding the impact of surges associated with the storms, the UN’s Intergovernmental Panel on Climate Change said in a 594-page report today that examines weather impacts from Alaska to Africa and Australia.

Coastal areas around the world, especially large cities and small islands, are particularly vulnerable to the impact of climate change and as much as $35 trillion, or 9 percent of projected global economic output in 2070, may be exposed to climate-related hazards in ports, the panel said. That may increase the need for migration, according to the authors.

“The decision about whether or not to move is achingly difficult and it’s one that the world community is going to have to face with increasing frequency in the future,” Chris Field, one of the report’s authors and a professor at Stanford University, said today on a conference call with reporters.

Sea-level rise may render parts of Mumbai uninhabitable while other cities with the largest number of people threatened by coastal flooding include Kolkata, India, Rangoon in Myanmar, Miami, Shanghai, Bangkok and Ho Chi Minh City, according to the study.

Photographer: Kevork Djansezian/Getty Images

People take photos of the Citibank digital thermometer showing the temperature at 121 degrees F at 3pm on Sept. 27, 2010 in Los Angeles, California. Heat waves are expected to increase, according to the UN study. Close

People take photos of the Citibank digital thermometer showing the temperature at 121... Read More

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Photographer: Kevork Djansezian/Getty Images

People take photos of the Citibank digital thermometer showing the temperature at 121 degrees F at 3pm on Sept. 27, 2010 in Los Angeles, California. Heat waves are expected to increase, according to the UN study.

U.S. Heat Wave

Economic losses from a 1-in-100-year flood in Mumbai could triple to $2.3 billion by the 2080s, according to the research. Sea-level rises and storm surges could combine to make coastal portions of the Indian city uninhabitable, it said.

Mumbai needs “early warning systems,” IPCC Chairman Rajendra Pachauri told reporters. “The drainage system is terrible and one would need to create new infrastructure.”

While people in the developing world are likely to suffer the most, developed countries will also be affected, and the U.S. is no exception, according to the study, which presents the background information to a summary published last year.

The U.S. has experienced a heat wave in March that’s seen 7,271 daily temperature records broken or tied from coast to coast, according to the National Climatic Data Center. That includes a March 22 record for New York’s Central Park of 78 degrees Fahrenheit (26 Celsius). The average monthly temperature in the park was 51.2 degrees through yesterday, 9.4 degrees above normal and 0.1 degree above the record from 1945.

Today’s study said with “high confidence” that heat waves in the whole of North America will become more frequent, longer or more intense this century.

Emissions Reductions

Decisions made now about the pace of emissions reduction could benefit future generations, according to another author of the report, Thomas Stocker, a professor at the University of Bern in Switzerland. Choosing a “lower emissions” development path could more than cut in half the instances of daily temperature records in 2100, he said.

“We can show therefore that there are immediate physical benefits in mitigation and choosing lower emissions scenarios,” Stocker said.

The study also found that damage caused by natural disasters has expanded more rapidly than the global population or economic growth. Economic losses caused by tropical storms may increase 30 percent by 2040 from 2000 levels, according to the median of nine studies cited in today’s report. Damage caused by river flooding may rise 65 percent in the same period, according to the median of six studies analyzed.

Hurricane Katrina

Changes in where populations live can affect the magnitude of losses, according to the study, which cited the area around the Gulf of Mexico, hit in 2005 by Hurricane Katrina, as an example.

“Population trends within the region have increased vulnerability by heightening exposure of people and property in areas that are affected by extreme events,” the scientists said.

Hurricanes Katrina and Rita destroyed more than 100 oil and gas platforms in the Gulf of Mexico, and disrupted 20 percent of U.S. refining capacity, according to the study. Katrina alone caused economic losses of $138 billion, it said.

Governments will need to combine carbon reductions with measures to adapt to rising sea levels, increased temperatures and more intense rainfall to find the most effective way to fight climate change, Pachauri said.

“There are huge disparities in terms of the impacts of very similar events and disasters in different parts of the world,” Pachauri said. “That’s a function of the vulnerability, the exposure and the kinds of preparedness and infrastructure that exist in different parts of the world.”

To contact the reporter on this story: Alex Morales in London at amorales2@bloomberg.net.

To contact the editor responsible for this story: Reed Landberg at landberg@bloomberg.net.

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