Climate Progress had a post yesterday discussing the current drought situation in Texas, including quotes like this:
Texas is in the midst of one of the worst droughts, in terms of the depth and expanse of drought conditions, since the early 1900s.I thought it would be interesting to pull the data to see how abnormal the current situation is versus the history of drought in Texas. Accordingly, I went to the National Climatic Data Center and obtained the data for the Palmer Drought Severity Index for Texas in March. That data goes back to 1895 and looks like this:
Dan Byrd, meteorologist with the National Weather Service in Jackson, Miss., said, “This is an unprecedented drought situation [in terms of] how widespread it is and the depth of the drought. We haven’t seen anything like this for the state overall since the early 1900s.
Koenig commented, “It’s pretty phenomenal and historic. The entire state is involved in this. When you look at the size of Texas, from the panhandle to the coast, you have about 1,000 miles.”
According to the latest analysis by the U.S. Drought Monitor on April 12, 2011, the entire state of Texas was experiencing abnormally dry or drought conditions with most areas in a severe to exceptional drought.
I've circled March 2011, so you can see how it compares to the history.
Recall the meaning of the PDSI, in which values of -2 to -3 are "moderate drought", -3 to -4 are "severe drought", and -4 and below are "extreme drought". So the current value of about -3.2 is indeed a severe drought. At least if the PDSI is to be believed, it's not unprecedented however: I count 15 different years which have had a lower PDSI in March than 2011.
I've also added a trendline, which you will note slopes upward (ie to wetter conditions). However, a regression comes up with a slope of 0.0056 ± 0.0075 PDSI units/year - ie. the trend is smaller than the uncertainty and so it's not a statistically significant trend. At any rate, there certainly is no evidence in the record that Texas is getting drier overall (at least in March, at least so far).
Climate Progress also links to a different indicator: data at the US Drought Monitor for the southern region, showing the fraction of the land area under different degrees of drought. The current map looks like this:
The data for this indicator only go back to 2000, so there's no way to do any kind of useful trend analysis. However, I plotted the fraction in severe, extreme, and exceptional drought as follows:
So again, while there is certainly a serious drought in Texas at present, even in the context of this extremely short record it does not appear to be unprecedented in scale or severity.
Our sympathies should of course go to the farmers affected by the drought, as well as to those affected by the wildfires. Let's not lose our sense of proportion and start exaggerating the significance of current weather conditions, however.