Is Global Warming Causing This Summer's Extreme Heat?

Aug 11, 2011; 9:25 AM ET

Sizzling, blistering, sweltering. There are a number of ways to say it, but they all can easily define the same thing. It's hot, and that is exactly what the conditions are across many locations in the United States.

It's no surprise the heat has been cranked on high this summer. The southern Plains has been broiling in the heat wave of 2011.

Urban centers from Oklahoma City to Dallas-Fort Worth have already set numerous records for high temperatures so far this year. Some locations are even breaking their record streaks of consecutive 100-degree days.

The month of July left residents in the South sweating through their shirts, and August is not acting any better.

This graphic shows the ratio of record daily highs to record daily lows observed at about 1,800 weather stations in the Lower 48 contiguous states from January 1950 through September 2009. Each bar shows the proportion of record highs (red) to record lows (blue) for each decade. The 1960s and 1970s saw slightly more record daily lows than highs. However, in the last 30 years, record highs have increasingly predominated, with the ratio now about two-to-one for the Lower 48 states as a whole. ((DUCAR, graphic by Mike Shibao)

As the summer pushes on, people are continuously dealing with the heat. There are questions that arise just as quickly as the mercury rises. 'What's causing this extreme jump in temperatures, and could it be global warming?'

"Certainly, there is a pretty good likelihood that global warming has something to do with this last intense heat wave that we've experienced across the United States," said Brett Anderson, sr.

meteorologist and climate change blogger. "It covered a large area, all the way from the Plains to the Northeast."

Anderson said there have been extreme temperatures also in Detroit and Washington, D.C., experiencing the warmest July on record.

"It's incredible," said Anderson. "I've never seen that before working here in my 22 years."

If the heat wave has not been a big enough problem, drought has also been added to the mix of issues. The dry conditions across the Plains have also had a big impact on the recent heat wave, according to Anderson. He said without moisture to evaporate, a bigger heat wave gets put into place, and it doesn't take much to make it extreme, especially across the Plains.

According to a new study, researchers found a warming climate has caused daily record high temperatures to be set twice as often as record low temperatures throughout the last decade in the U. S.

"Climate change is making itself felt in terms of day-to-day weather in the United States," said Gerald Meehl, the lead author and a senior scientist at the National Center for Atmospheric Research (NCAR). "The ways these records are being broken show how our climate is already shifting."

The study was led by researchers from NCAR, Climate Central, The Weather Channel and the National Oceanic and Atmospheric Administration (NOAA).

Anderson explained that the problem lies within the release of greenhouse gases, like carbon dioxide.

"We're increasing CO2 in the atmosphere," said Anderson. "We've all talked about greenhouse gases that trap heat. As we continue to produce more greenhouse gases over the years, we'll have more of a lid, just trapping that heat. That in turn gives us a greater potential for extreme heat waves, which we saw, obviously, this summer."

If greenhouse gases continue to be released into the atmosphere, the ratio of record highs to record lows will continue to increase, according to the study.

"In the end, if the ratios increase, there's a likelihood of having more extreme heat waves over the next 20 to possibly 50 years," said Anderson. He said all signs point to a worse situation in the next 10 to 20 years in terms of heat waves.

A few months back, we discussed on the possibility of linking global warming to severe weather events.

While there could be a relationship between the two, it's difficult to draw a comparison from one event in one area to global warming, Anderson explained.

"With a heat wave, it's much more widespread and it covers a larger area," said Anderson. "It also lasts for days, weeks and months. So it's much easier to draw a link there.


Jim G. Munley, jr.

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