Though New Yorkers wouldn't know it from the largely damp and chilly Memorial Day weekend, summer heat in Manhattan could be turning deadly, according to a study out of Columbia University.
Worse yet: the study found the greatest increase in temperature-related deaths would occur during typically pleasant May and September.
Researchers at the university's Earth Institute and the Mailman School of Public Health are apparently warning that deaths in Manhattan linked to warmer temperatures due to global warming may result in a 20 percent increase in temperature-related deaths by the 2020s.
In some worst-case scenarios, according to the Earth Institute, the rate of heat-related deaths could rise by 90 percent by the 2080s.
While global warming could also bring rising winter temperatures, scientists say, the rise in heat deaths would likely not be offset significantly by a decrease in cold-related deaths. Annual net temperature-related deaths may still increase by a third.
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This Manhattan-focused study is reportedly one of the most comprehensive studies so far on adverse health effects associated with rising temperatures as it combines data from all seasons and looks at multiple scenarios in one localized area—an area that happens to be the most densely populated county in the United States.
A coauthor of the study, Earth Institute climate scientist Radley Horton, pointed to the 55,000 deaths that occurred during the record 2010 heat wave in Russia, and the 70,000 deaths that occurred in 2003 in central and Western Europe.
"This serves as a reminder that heat events are one of the greatest hazards faced by urban populations around the globe," Horton said.
Heat apparently becomes concentrated in cities, as the pavement and buildings absorb it during the day and give it off at night.
2012 was apparently the warmest year on record in Manhattan. While projections for the future vary, the study anticipates steep average increases: 3.3 to 4.2 degrees Fahrenheit by the 2050s, and 4.3 to 7.1 degrees by the 2080s.
The study looked at two potential futures: one where global population growth happens alongside minimal efforts to limit greenhouse gas emissions; the second assuming slower population growth and advances in technology that could decrease emissions by 2040. Their baseline for temperature-related deaths was the 1980s, when as estimated 370 Manhattanites died from excessively hot temperatures and 340 died from extreme cold.
In both scenarios, the study anticipated increased mortality. Varied results were credit to the unpredictability of the future of greenhouse gas emissions, but researchers said the best-case scenario would involve a 15 percent increase in temperature-related death; worst-case would be an increase of more than 30 percent.
Senior author Patrick Kinney, an environmental scientist at the Mailman school, said the situation could be affected, positively or negatively, by how New York adapts its infrastructure and policies to a warmer world.
"I think this points to the need for cities to look for ways to make themselves and their people more resilient to heat," he said.
The Earth Institute noted that New York already takes steps to mitigate warming by planting trees, making roofs reflective, and opening cooling centers in the summer time where people can seek refuge in rising temperatures.
Hot tips from the Department of Health
The Department of Health advises New Yorkers without home air conditioning to call 311 to find their nearest cooling center during a heat wave, or go to a nearby library, museum or department store. Hydration is important, but drinks with alcohol, caffeine and lots of sugar should be avoided.
While the DOH advises people to use air conditioning during the summer, the department also warns that the city is vulnerable to power outages during a heatwave, so thermostats should not be set below 78 degrees, and water should be used conservatively during extreme weather. Cool showers are recommended, but sudden temperature changes could cause dizziness or sickness.
Follow Danielle Tcholakian on Twitter @danielleiat