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Posts Tagged ‘urban heat island’

Predictions for the Big Apple haven’t been so great lately, at least as far as climate is concerned. News from a week ago was that heat-related deaths are predicted to rise by 20% by the 2020s and by nearly 100% by the end of the century. Scientific American summarizes the work published this month in the journal, Nature Climate Change, and includes this quote from one of the authors:

“This serves as a reminder that heat events are one of the greatest hazards faced by urban populations around the globe,” said coauthor Radley Horton, a climate scientist at the Earth Institute’s Center for Climate Systems Research.

The record 2010 heat wave that hit Russia, killing some 55,000 people, and the 2003 one in Europe that killed 70,000 are potent examples of the devastation that extreme heat can cause, Horton added.

This week, Scientific American published another warning for NYC and the rest of the East Coast. The climate threat in this case is flooding – the possibility of Hurricane Sandy-like flooding every two years by century’s end! Salon summarizes the SA behind-the-paywall story here.  A few planning details:

Municipalities rarely plan for anything greater than the so-called one-in-100-year storm—which means that the chances of such a storm hitting during any given year is one in 100. Sandy was a one-in-500-year storm. If sea level rises by five feet, the chance in any year of a storm bringing a three-foot surge to New York City will increase to as high as one in three or even one in two, according to various projections. The 100-year-height for a storm in the year 2000 would be reached by a two-year storm in 2100.

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Jim Robbins, author of a forthcoming book called The Man Who Planted Trees, has an op-ed in today’s New York Times that alerts readers to the mounting threats to trees and the reasons why the planet needs them more than ever. The lines below caught my attention, especially the repercussions from the Texas drought that I discussed in a post last summer.

North America’s ancient alpine bristlecone forests are falling victim to a voracious beetle and an Asian fungus. In Texas, a prolonged drought killed more than five million urban shade trees last year and an additional half-billion trees in parks and forests. [Emphasis added.] In the Amazon, two severe droughts have killed billions more.

The common factor has been hotter, drier weather.

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Climatewire (subscription service), from E&E Publishing, reports the surprising conclusion of a study just published in Environmental Research Letters. Some cities, like Dallas, TX, may not be cooled by deployment of white or light-colored roofs and pavements while other cities, like Los Angeles, are. Regional variation is apparent. The study also looked at the effect of desert photovoltaics, with their low albedo (reflectivity), on temperature and found that they can increase an area’s temperature by approximately 0.5° Celsius. White or light-colored roofs and pavements deflect heat, bouncing it back into the atmosphere and creating the cooling effect we desire. But, the study conducted by scientists at the Lawrence Berkeley National Laboratory suggests that there is a feedback effect whereby the bouncing sunlight can disrupt wind and cloud patterns, leading to changes in a region’s hot and cold spots. In humid Dallas, for example, clouds have a cooling effect on a hot day, and deflected heat from white roofs (if deployed widely) could limit cloud formation and therefore raise temperatures according to the study’s model. The researchers conclude that cool roofs are still useful tools, but that the effects might not be as uniform as we may have thought. Regional weather patterns should also be taken into consideration.

The study is available here.  Milstein, D. and S. Menon. 2011. Regional climate consequences of large-scale cool roof and photovoltaic array deployment. Environmental Research Letters 6(3).

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