Astronomical Climate Projections for the Allegheny Highlands

At The Daily Athanaeum in Morgantown, West Virginia, there are some serious concerns being expressed about the potential impacts of climate change on the Allegheny Highlands.

According to the article:

Friends of Blackwater's Allegheny Highlands Climate Change Impacts Initiative present a series of regional public outreach and educational programs on the topic: 'Climate Change and the Allegheny Highlands: What’s at Stake, What's at Risk, and What are Our Choices?'

Brian Bellew, a member of Friends of Blackwater, gave a demonstration of the organization's prototype presentation to the West Virginia University Sierra Student Coalition, a student branch of The Sierra Club -- the nation's largest and most influential grassroots environmental organization ...

'If carbon emissions aren't cut, we are on pace for an 11 degree Fahrenheit increase by the end of the century,' Bellew said. 'The climate-sensitive highlands ecology and economy are on the chopping block from the impacts of global warming and climate change.'

This is an astronomical prediction.  An 11º F increase in temperature from current conditions on the Allegheny Highlands would represent an increase rate of 12.8º F per century between 2014 and the year 2100.

While the northeastern portion of the U.S. has apparently seen larger temperature increases since records began in the late 1800s than has the rest of the nation, being on pace for a nearly 13º F-per-century rate of temperature increase over the next 85 years seems very large.

So I looked at temperature trends for the climate divisions in Pennsylvania, Maryland, West Virginia, and Virginia that include and surround the Allegheny Highlands.

Much of the region hasn't seen any significant trend in annual temperatures since the NOAA National Climatic Data Center records began in 1895.  Those regions that have seen temperature increases over the past 120 years exhibit only modest rates of change (from 0.7º to 2.1º F per century).

As with so much of climate science, the devil is in the details.  During the last three decades, three quarters of the relevant climate divisions have no significant trend in annual temperatures.  The three divisions that do have significant trends (one each in Virginia, Maryland, and Pennsylvania) over the last 30 years are coming in at between 5.3º and 6.0º F per century – well below 12.8º per century.

So we must conclude that the vast majority of this region has an unchanging temperature over the last few decades, and even the small region that does have significant trends is changing at rates far below that quoted in The Daily Athenaeum's piece.

But even that conclusion appears to overstate the real rate of change.

From looking at the annual climate data throughout this region, it is clear that the rate of change – for those few regions still having significant trends – is slowing over the last decade or two.  The 2014 dataset is not yet complete, but based on 12-month annual records from December to November of each year (an equally valid analytical approach to the conventional January to December calendar year method), 2014 is coming in as much colder than normal throughout the Allegheny Highlands area.  One assumes that the December 2014 data won't change this conclusion.

Here is the current December to November annual temperature for Maryland's eighth climate division – the representative "Allegheny Plateau" division – since records began.

The last datapoint is the December 2013 through November 2014 "year."  What this time series nicely shows is that – in the Allegheny Highlands area (as with so many other areas in the U.S.) – we may be seeing the top of a climate cycle and the beginning of a cooling trend.

And this is exactly why we need to be far more cautious when making climate projections.

Overall, the Allegheny Highlands climate region hasn't seen much temperature change over the past 120 years, and if we get excited and start extrapolating the increasing trends from a minority of regions over the last few decades, we may be committing a gross error by failing to incorporate the well-established cycling seen in the area since we began collecting climate data.

Based on what we have seen since 1895, and certainly over the last few decades, there appears to be just as good a chance that the annual temperature in the Allegheny Highlands will decline in coming years as increase.  And the region certainly doesn't appear to be on track for an increase of 13º F per century during the next eight decades.