Feverish Times for Climate Change Analyses in Virginia

A new book with climate predictions for the state of Virginia is being discussed in the media:

The book lays out climate projections for Virginia by Texas Tech University Professor Katharine Hayhoe, an atmospheric scientist. For the first time, the data allows Virginians to consider projected temperature increases where they live as the global average temperature rises.

If greenhouse gases continue to accumulate in the global atmosphere at current rates, Fairfax County could see nearly double the number of 90+ degree days in a typical summer over the next few decades, and more as the heat continues to build. In Richmond, sticky summer days of 90+ could increase from from 36 days to 60, well before mid-century. Even Highland County, known for its pleasantly cool summers, could see 90-degree days quadruple, with more on the way as global warming increases.

'Steve Nash's book allows Virginians to glimpse a future they can still shape,' said Michael Mann, a former University of Virginia climate scientist who is now a professor of Meteorology at Penn State University. 'If we don't like that future, we can take actions now to reduce carbon pollution – actions like the U.S. EPA's Clean Power Plan to reduce carbon pollution from fossil fuel power plants,' Mann said.

In other media coverage, we read the following:

Nash asserted that if greenhouse gases continue to be emitted at their current rate, then cities such as Arlington, Richmond and Charlottesville will have twice their current number of 90-plus degree Fahrenheit days. In doing research for his book, Nash interviewed and gathered research from dozens of scientists who monitor climate change. The research documents the incremental rise of temperatures in Virginia, a trend which began sometime in the mid-1970s.

The NOAA National Weather Service database maintains records on 90+ days in Virginia – although the records for individual sites are rather spotty.  For Charlottesville, the 90+ days record begins in 1950, and since this date, the correlation has been toward fewer – not more – hot days.  Over the last three decades at Charlottesville, there is almost a perfect non-correlation in number of 90+ days.

In the Richmond area, there has been no significant trend in the number of 90+ days each year over the past three decades, or even since 1970, nor since 1950.  There has been a significant increase since records began in 1897, but all of the increase occurred prior to 1950, and since the 1950s there has been no significant trend.  That trend pattern simply does not seem consistent with anthropogenic global warming causation.

At the Ronald Reagan Washington National Airport site in Arlington (where records begin in 1942), there have been no significant trends in 90+ days since 1950, since 1970, or over the last decades.  Nearby in the Sterling-Dulles Airport climate sub-region (records begin in 1963), there have been no significant trends in 90+ days since the records start, or since 1970, or over the past three decades.  Once again, the past three decades have seen an almost perfect non-correlation for hot days.

Overall, there are no significant trends in 90+ days since 1970, or over the past 30 years, for the state's Norfolk, Richmond, Lynchburg, Roanoke, or Sterling-Dulles Airport climate sub-regions – which is effectively the entire state.  At the isolated Wallops Island site, there is a significant increase since 1970, but not since 1984.

Using data from the NOAA National Climatic Data Center, there has been no significant trend in the state's summertime average maximum temperature since records began in 1895, and also no significant trends since either 1970 or over the last three decades.  Five of the six climate divisions in Virginia have no significant trends in summertime average maximum temperature over the past 120 years, whereas the single “Northern” climate division does have a significant trend since 1895, but not since 1970, nor during the last 30 years.

Overall, it doesn't appear that 90+ days are increasing in Virginia, nor are summertime maximum temperatures.  These facts should provide some temperance to climate predictions before we engage in irresponsible policy responses to a very poorly defined problem.

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