Are TV Weathermen in a Fog About Global Warming?

Many TV weather forecasters are deniers of global warming, according to a recent article in The New York Times citing a just-released survey by researchers at George Mason University and the University of Texas at Austin.  Only about half of the 571 weathercasters surveyed believed that global warming was occurring, while more than a quarter of them agreed with the statement that “global warming is a scam.”  http://www.nytimes.com/2010/03/30/science/earth/30warming.html. 

The leading proponent of the scam theory is San Diego TV weatherman John Coleman, formerly of “Good Morning, America” and a co-founder of The Weather Channel.  He claims that NASA is deliberately manipulating world temperature data as part of a conspiracy to bring about world government.  Joe Bastardi of AccuWeather flatly asserts that the earth is probably cooling.

Accurate is not a word I would use for most TV weather forecasts, nor would I consider TV weather personalities the equal of scientists in evaluating long-term climate change.  But one thing that meteorologists do well is recording actual temperatures, including daily highs and lows.  So I decided to review some of their own data.   

While global warming studies typically cite changes in average temperatures, I thought that record high and low temperatures might accentuate any warming or cooling trends.  Since I live in Massachusetts, and Boston has kept accurate weather data since 1870, I used that city for my little study.  I divided the past 140 years into 14 decades (1870-79, 1880-89, etc.) and looked to see in which of those decades the current record highs and lows for each day of the year occurred.  For example, the record high for January 1 is 70, set in 1876, so put that in the column for 1870-79.  The record low for the date is -3, set in 1918, so that goes in the 1910-19 column.  And so on for each day of the year (except February 29).

Totaling up the results, it is clear and unmistakable that there has been a warming trend in Boston over that time period.  In the seven decades from 1870 through 1939, 137 daily high temperature records were set which still stand today.  But in the seven decades since, 228 record daily highs were set, 66% more than in the previous period.  The trend is even more pronounced comparing the three earliest decades, 1870-1899 (when people had no cars, electricity, oil or natural gas central heating systems, air conditioning, etc.) with the three most recent decades, 1980-2009.  40 daily high temperature records set in those first three decades still stand today.  But in the three most recent decades 113 daily highs have been set, over 2.8 times as many.

The trend is even more dramatic looking at record low temperatures.  From 1870 through 1939,  262 daily low temperature records were set, versus only 103 record lows set in 1940-2009.  That’s over 2.5 times as many record lows in the first seven decades versus the last seven.  And looking at just the first and last three decades, there were 156 record daily lows set in the former, and only 30 in the latter.  That’s 5.2 times as many record lows set in the first 30-year period as in the latest one.

Could natural causes alone be responsible for such a dramatic swing in record high and low temperatures?  Highly unlikely, because without some major catastrophe, natural climate change would occur much more gradually over a much longer period of time.  Are cities warmer today than they were in the 19^th century?  Well yes, and human activity is obviously responsible for that.   And what about temperature trends in cities other than Boston, like San Diego?  I’ll leave that for climate researchers to explore, because I’m no scientist.  But based on the data from one city, there is a clear warming trend in less than a century and a half, one which is accelerating in recent years.  TV weathercasters who can’t see that trend in their own weather data must be in a fog.  And you don’t need a weatherman to know which way the climate goes.