Since we are now in for a couple of days of tranquil weather, I thought that I would present the second part of my three-part series on local warming.
In part 1 (January 23) I analyzed local climate trends using the official data available for the city of Galveston since 1871. This data, confirms what many locals already have recognized. Temperatures in Galveston have risen overall in recent years, particularly since 1990, and now stand at the warmest levels since observations began in 1871.
In part 2, I examine our winter-time weather. Again many area residents, particularly gardeners, have noticed that winters are significantly warmer now than they were 20-30 years ago. What is especially evident is the absence of any hard freezes on the Island and the consequent changes in the types of vegetation that now flourish here.
Again, the climate statistics support these impressions. In 1903, the average winter-time (December through March) temperature was 55.0 degrees (based on observations from 1871-1903). Subsequently, the three month winter average hovered consistently around a 55 degree average. In 1940, it was 55.5 degrees, in 1980, it was 55.3 degrees. In 1990, the average was 54.9 degrees, but by 2000 the average had jumped to its highest level since observations began, with a 57.3 degree average. Since 1991, when the warming became most evident the winter-time average has been 57.4 degrees in the city. This jump of 2 degrees may not seem significant, but it is the equivalent of moving at least 125 miles further south down the coast.
Perhaps the greatest change in our winter-time weather, however, has not been the rise in the average temperature, but the virtual disappearance of hard freezes on the Island. From 1871 through 1989, the coldest temperature in Galveston by each decade on average was 16 degrees. Since 1990, the lowest ten year temperature in the city has averaged 27 degrees.
Looking at this another way, from 1872-1899, 71.4% of the years had a "hard freeze" (defined for purposes of our local vegetation as a temperature below 30 degrees) and 53.6% of the years had a "very hard freeze" (defined as a temperature of 25 degrees or lower). From 1900 through 1989, 63.7% of the years had a hard freeze and 36.6% had a very hard freeze. Since 1990, only 11.1% of the years have had a hard freeze and 11.1% have had a very hard freeze (representing the 24 degree low temperatures observed in 1990 and 1996). The city has now gone an unprecedented 11 years without a hard or very hard freeze.
You might say, as I have on occasion, "What is so bad about that? I do not like cold weather anyway". Certainly, it is nice to be able to grow the semi-tropicals and tropicals that now beautify our gardens, and the lower heating costs are more than welcome.
But, as we shall see in part 3 of this series in a few weeks. This warming trend has also dramatically affected our summer-time climate. The unpleasant side of this warming trend has been markedly warmer summer temperatures and the associated higher cooling bills.
http://galvestondailynews.com/blog.lass ... 24bb3c0ce5
