Texas Climate Trends
By Paul Homewood
h/t Slimething
Texas State Climatologist, John Nielsen-Gammon, had some interesting things to say about Texas Climate Stats on his blog for the Houston Chronicle yesterday.
Boiling it all down to basics, he had this to offer:-
- The year ended up with below-normal precipitation, the combined two-year period 2011-2012 was the fourth-driest on record, beaten only by 1916-1917, 1955-1956, and 1909-1910.
- The long-term linear trend in Texas precipitation is +7.8% per century.
- The year 2012 was also a warm year for Texas. Depending on the final tally, it will be either the warmest or second-warmest year ever, with statewide records beginning in 1895. The only potential rival is 1921; 2011 ran a distant third.
- These temperatures are also part of a long-term pattern, in this case warming by almost 1.5 F since the 1970s
Well, let’s put these statements into some sort of perspective.
1) It is, of course, a bit of cherry picking for JNG to quote “two year” periods for drought comparisons. Why not one, or three, or four? As NOAA’s precipitation graph below shows, while 2011 was exceptionally dry, this year is only slightly below average, and recent years have been above average. (December numbers are not out yet, so I have used Dec 2011-Nov 2012).
Climate At A Glance
Most Recent 12-Month Period (Dec – Nov) Precipitation
Texas
Most Recent 12-Month Period (Dec – Nov) 1901 – 2000 Average = 27.92 Inches
Most Recent 12-Month Period (Dec – Nov) 1895 – 2012 Trend = 0.02 Inches / Decade
At the end of 2013, will JNG be discussing “three year” periods?
2) JNG does, of course, confirm that long term rainfall trends have been increasing in Texas, as this graph indicates.
Climate At A Glance
Most Recent 12-Month Period (Dec – Nov) Precipitation
Texas
Most Recent 12-Month Period (Dec – Nov) 1901 – 2000 Average = 27.92 Inches
Most Recent 12-Month Period (Dec – Nov) 1895 – 2012 Trend = 0.02 Inches / Decade
3) As for temperatures, JNG may well be right, as he will have access to December figures, that are not published yet. Nevertheless, the Dec 2011 – Nov 2012 figures tell a slightly different story.
Search Field:
NCDC / Climate At A Glance / Climate Monitoring / Search / Help
Climate At A Glance
Most Recent 12-Month Period (Dec – Nov) Temperature
Texas
Most Recent 12-Month Period (Dec – Nov) 1901 – 2000 Average = 65.05 degF
Most Recent 12-Month Period (Dec – Nov) 1895 – 2012 Trend = 0.01 degF / Decade
For the Dec – Nov periods, 1921, 1927, 1934 and 2011 were all hotter.
4) However, JNG really goes full-Hayhoe, when he says “These temperatures are also part of a long-term pattern, in this case warming by almost 1.5 F since the 1970s.”
The long term trend since 1895, as NOAA show, is only 0.01F/decade. A whole 0.1F per century!
It is dishonest to pretend otherwise.
Hurricanes
I cannot finish without a passing mention of hurricanes and tropical storms.
David Roth, of the NWS, wrote a paper, “Texas Hurricane History”, a couple of years ago. In it, he made the following comment.
Of the 122 storms chronicled in this survey, 11 are credited with alleviating drought conditions across the Lone Star State. Without tropical storms and hurricanes moving into Texas, summer rainfall would be about 10% lower than what currently falls across eastern Texas. This could be disastrous for cotton, corn, and rice grown statewide, as they are highly dependent on this added rainfall contribution.
Roth’s history goes back to 1850, so, on average, there is a Hurricane or Tropical Storm most years. There have been none in the last two years, and this is certainly one factor in below average rainfall.
None of this will stop certain people jumping up and down, shouting “extreme weather”, the next time Texas gets hit with one.
UPDATE If you wonder why I’ve called him JMG, and not JNG, don’t worry. I’ve been wondering as well!! [Now corrected]
Comments are closed.
NOT A LOT OF PEOPLE KNOW THAT 
Nice work.
Typo? – “As NOAA’s precipitation graph below shows, while 2012 was exceptionally dry, this year is only slightly below average,…” Should that be 2011?
Thanks!!
Under the last graph (red line as Actual Temperature) there is JMG’s 1.5 F degrees since the 1970s and NOAA’s 0.01 F degrees per decade since 1895. In themselves, these are hard to compare. I’ll go with the visual image and argue this is a case where the picture is worth 1,000 words. The few words offered are insufficient to describe what the temperature has done.
Take any period, say a running 15 years, and note the large swings. Several of the larger changes, both up and down, occur from one year to the next. That’s one message.
If records began in 1975 (?) one could believe an upward trend. If records existed for only the years 1935 thru 1980 one could believe a downward trend. That’s another message.
Looking at the entire 1895 thru 2012 record there seems to be another message. From about 1965 to 1997 almost all the points are below or just slightly above the average. To notice this is to say that prior to 1965 there was a general “up” time and after 1997 there was an “up” time. So, I see periods of “up – down – up” with a calculated “trend” not distinguishable from zero given the quality of the data. Describing the “quality of the data” would take me past the 1,000 word limit.
JNG, Hayhoe and co, are so keen to blame warming in Texas since 1970 on global warming. Yet they never explain why temperatures dropped in the previous decades.