Sweating It Out: U.S. Cities Have 10 More Hot Nights A Year Than 40 Years Ago
If you think that summers are getting hotter, you could be right—depending on where you live. Summers are heating up if you live in or near any major U.S. city. But in rural areas, temperatures have remained relatively constant. "What surprised me was the difference in the extreme temperature trends between rural and urban areas," said Arthur T. DeGaetano, Cornell University associate professor of earth and atmospheric sciences, who reviewed temperature trends from climate-reporting stations across the United States over the past century and examined data from the last 40 years in greater detail. "I expected maybe a 25 percent increase for the urban areas compared to the rural ones. I didn't expect a 300 percent increase across the U.S."
Because of population growth in urban and suburban areas over the past four decades, particularly in major East Coast cities, there are more hot summer nights than ever, said DeGaetano. "This means that cities and the suburbs may be contributing greatly to their own heat problems," he said. "Greenhouse gases could be a factor, but not the one and only cause. There is natural climate variability, and you tend to see higher temperatures during periods of drought."