Texas must secure a reliable, long-term water supply

Texas Water Supply

 

I used to get annoyed when it rained.

Not anymore.

The drought that began in October 2010 demonstrated the vital importance of water to our economy, our health and our natural environment. The mere threat of water shortages can be enough to send tourists scurrying away and cause businesses to look for more reliable water supplies elsewhere.

The drought was the worst one-year drought in Texas history, and while it has ended in much of the state, it’s still going strong in many parts of western, central and southern Texas.

This drought has reminded us of the importance of doing what it takes to ensure adequate water supplies for the future. The Academy of Medicine, Engineering & Science of Texas is holding a critical issues forum – the 2012 Texas Water Supply Summit: Securing Water for Texas’ Future – on May 20-21 in Austin. This timely forum will address the political, economic, technological and scientific challenges of providing for future water needs, now that Texas is outgrowing its water supply infrastructure.

One of the greatest scientific challenges is figuring out just how much fresh water will be available in Texas. Climate change is not as important as population growth for Texas water supply, but it’s still too big to ignore.

It used to be that we could get away with assuming that the climate was unchanging, that to plan for the future, one simply had to plan for the past. We’ve been lucky so far. According to recent research, natural variability has kept temperatures down from here to the Carolinas even as they’ve risen nearly everywhere else around the globe. But our luck is running out. Last decade was the warmest decade on record for Texas, and this decade is not off to a good start.

Predicting climate change and its effects is quite a challenge. Scientists don’t know whether our main drought trigger, La Niña, will become more frequent, less frequent, or stay about the same. We don’t know whether Texas rainfall will continue its century-long upward trend or reverse itself. We don’t know exactly when the long-term ocean temperature patterns that have helped bring Texas 15 years of on-and-off drought will go away.

In the short term, neutral to El Niño conditions are likely next winter. This would tilt the odds toward above normal rainfall in Texas beginning in late fall. But this is not a sure thing yet, and first we have summer to deal with.

There is one reasonably safe bet for the next few decades: Greenhouse gases will continue to rise, and this tilts the odds strongly toward warmer temperatures. And whether it’s just another degree warmer by mid-century or as much as three degrees warmer, the warmer weather, day in and day out, will affect our Texas water supply.

Higher temperatures mean more evaporation. More evaporation means more water needed by crops and plants, but less available in streams and rivers. While less water reaches our reservoirs, more water evaporates away from those reservoirs before it can be used. Higher temperatures mean greater power demand, and at the same time there’s less water for power generation.

Natural variability bailed us out in the latter half of the 20th century. Only a fool would bet on natural variability to bail us out again.

We need a reliable water supply in Texas, no matter what the climate brings us.

I used to enjoy warm, sunny days.

I admit, I still enjoy them, but now they make me just a little bit uneasy.

John W.  Nielsen-Gammon, a professor at Texas A&M, is the Texas state climatologist.

Texas Water Supply

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