The first nine months of 2012 were the hottest in Pittsburgh in 65 years, and long-term trends indicate an even warmer future, according to data released Tuesday by the National Oceanic and Atmospheric Administration.
The contiguous United States also experienced the warmest first nine months on record, as did 109 of 180 individual long-term temperature reporting stations across the nation. Thirty-one more reporting stations recorded their second- or third-warmest first nine months ever.
Jake Crouch, a NOAA climate scientist, said the city's temperatures are significantly higher than normal and almost certainly not a product of random weather patterns.
"They are a significant departure -- 274 days of data. The fact it's been so warm for so long is significant," Mr. Crouch said. "And when you see how 2012 compares to other years, you see the really warm years are more recent and the really cold years are not. That's another indicator of a long-term warming trend."
According to the NOAA's data, temperatures measured at the Pittsburgh International Airport from January through September averaged 57.8 degrees Fahrenheit, compared to the 1981 through 2010 average of 54.2 degrees, an increase of 3.6 degrees. The chances that such high average temperatures could occur randomly are only 4 in 100.
Mr. Crouch said there are older temperature records in Pittsburgh and most cities, but NOAA used the most robust records from single locations. Many of those stations are located at city airports.
Other cities in the region that also experienced warmest ever first nine months of the year include Erie (87 years), Harrisburg (65 years), Scranton (63 years), Allentown (65 years), and Philadelphia (65 years) in Pennsylvania; Buffalo, N.Y. (74 years), and Cincinnati (65 years), Cleveland (74 years) and Columbus (65 years) in Ohio.
The temperature monitoring station in New York City's Central Park, which has the longest running data, showed the warmest first nine months in 137 years.
Mr. Crouch said NOAA uses the local temperature statistics to extrapolate statewide and regional and national climate trends. That data is available for use by the public, businesses and government officials for everything from how much road salt to buy to how much to budget for air conditioning.
M. Granger Morgan, who heads Carnegie Mellon University's Department of Engineering and Public Policy, said NOAA's temperature numbers are another example of how mounting data continues to support the probability that climate change is occurring.
"What has happened is that scientists are looking at extreme heat and extreme precipitation and extreme events and looking at the probability that the events could occur by chance," Mr. Morgan said. "But the odds are continuing to shrink that this is not just variability, and that all of these events are related to climate change."
Michael Mann, a Pennsylvania State University professor and director of the school's Earth Systems Science Center, said the NOAA data shows the climate, locally and nationally, is warming.
"The changes in climate have now reached the point where we can actually perceive their impact on our daily weather," Mr. Mann said in a written statement in response to questions.
And the record-breaking temperatures in Pittsburgh and throughout Pennsylvania are not isolated observations, he said, but occurred during the warmest year on record when high temperature records fell at 10 times the expected rate than if the climate weren't warming.
"We are now seeing the 'loading of the weather dice' by human-caused climate change," Mr. Mann said. "And we will see more widespread heat, summer drought, wildfire and other impacts here in the U.S. if we continue to add greenhouse gases to our atmosphere through fossil fuel burning and other activities."
A chart of all 180 reporting stations' temperature measurements can be found at www.ncdc.noaa.gov/sotc/national/2012/9/supplemental/page-1.
Don Hopey: email@example.com or 412-263-1983.