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Global warming is a complex and difficult topic. It is not easily addressed in a few comments. As a result, much of the public debate on the subject generates more heat than light (pun intended). Many comments seem to have been plucked wholesale off of talk radio or from websites clearly pushing a particular ideology or point of view, rather than scientific understanding.
I refer those truly interested in the subject to such journals as Nature, Science, Journal of Geophysical Research and the Scientific American. All of these have published, and continue to publish, articles on climate change.
Rather than get into this frequently fruitless debate, I want to focus on climate change as it is impacting our local weather. Fortunately, the data for our area is clear and unambiguous. Even if you haven't noticed the longer growing seasons, changes in vegetation and migratory bird habits, you are probably aware (if you have lived here long) that our climate here in southeast Texas is noticeably warmer than it was a generation ago.
In part 1 of this blog, I will present data on how our yearly climate has changed. In part 2 (which I will offer in the next couple of weeks), I will do the same for our winter climate and in part 3 (late spring) I will examine how our summer weather has changed.
The city of Galveston is fortunate in that it has continuous climate data stretching back to 1871. This provides us with an excellent snapshot of climatic variations over time.
First, what has happened to our overall yearly climate?
Since 1950, the National Weather Service has used 30-year averages (updated each new decade) to summarize climate data for its various locations. For example, the current official data set is based upon the years 1971-2000. In 2011, it will be based on the years 1981-2010.
The current average yearly temperature is 71.2 degrees. This is significantly warmer than any comparable period in the past. The average from 1961-90 was 69.7 degrees. For 1951-80 (69.6 degrees), 1941-70 (69.8 degrees), 1931-60 (69.9 degrees), 1921-1950 (70.1 degrees...the warmest until the latest 30 year average). In 1920, the cumulative yearly average (dating back to 1872) was 69.6 degrees and If we go back to the 1872-1901 era, it was also 69.6 degrees. In other words, the past 30 years have been the warmest period since observations began in 1871. Now a yearly rise of 1-1/2 degrees may not seem like much, but it is the equivalent of climatically moving almost 100 miles further south down the coast.
But this is just part of the picture.
The average yearly temperature since 1990 (when our warming spell clearly set in) has been 71.4 degrees, showing a continued upward trend. In fact, only 5 of the 118 years prior to 1990 had annual average temperatures that matched or exceeded the AVERAGE of the past 30 years! In other words, what was once exceptional is now ordinary.
We can further illustrate this rather remarkable statistic. From 1872 through 1899, just 1 of the 29 years of observation even matched (or exceeded) what is now our yearly norm. Nine of the 11 warmest years ever observed in Galveston have occurred since 1990. Three of the top four warmest years have come since 1994 and the last four consecutive years have surpassed even our current record-warm average.
This is at best a persistent and unmatched spell of warm years, unlike anything seen since weather observations commenced here.
In the next blog on this topic, I will look at how our winter climate has changed. Our winter-time weather presents an even clearer picture of the changing climate and is easier to portray than the somewhat nebulous concept of yearly temperature average.....but, more on that later.
About Stan Blazyk
Stan Blazyk is a weather expert and the author of A Century of Galveston Weather: 1900-1999 People and the Elements on a Barrier Island.
A UTMB retiree, he produces a daily weather forecast for Galveston.com, offers courses on various aspects of climate through the Osher Lifelong Learning Institute at UTMB and serves as a lecturer for the Elder Hostel program at Texas A&M-Galveston.
