The summer of 2012 is beating heat records in the contiguous United States as well as southern Canada, and is in the running for the hottest summer on record. According to the National Oceanic and Atmospheric Administration (NOAA), more than 40,000 daily heat records have been broken around the country so far this year, and we’re only midway through July.
This warm summer follows a remarkably warm winter. Jeff Weber, a scientist with the University Corporation for Atmospheric Research in Boulder, CO said that this winter was the hottest and driest that the western United States has ever seen since records have been kept. This unusual amount of heat can be explained in part to a persistant high pressure system located over the mountain west. It is now shifting east but seems to be stuck in place because of the inactivity of the North Atlantic Oscillation, a climate pattern that pulls weather patterns eastward, Weber says.
Weber told OurAmazingPlanet that this “blocking” of the Atlantic has caused the jet stream, which normally carries air west to east, to buckle and trap heat in the Midwest and Southeast.
Could climate change also be a factor in this excessive heat wave? An individual event such as this is difficult to trace back to the effects of a warming climate, but Greg Carbin, a meteorologist for the National Weather Service stated, “An increasing frequency of heat waves – that’s one aspect of climate change you can point to.”
Steven A. Root, certified consulting meteorologist and president and CEO of WeatherBank Inc., has been studying hourly and daily temperatures in 59 hub cities dating back to January 1, 1950. He calculates the cooling degree days (CDD) for each city, each day of the year. Cooling degree days are the number of degrees that a day’s average temperature is 65 degrees. May 15 to September 15 is considered the conditioning/cooling season for the U.S. and Canada.
Root is estimating this summer to finish up with 59,484 CDD’s based on previous months and what is projected. Comparatively, the summer of 1965, the coolest summer on record, had 43,337 CDD’s.
“In the recent five years, I have had to manually override the data due to the high number and magnitude of temperature extremes, compared to prior decades,” Root said. “This tells you that the summers are trending hotter…for the U.S. and southern Canada as a whole.”