Global warming, monsoons, and engineering

Depending on where you live in the United States, if you ask someone what the worst problem facing humanity is today, you'll get different answers. On the coasts, apparently, at least in cities and among the knowledge classes, one of the most common answers will be "climate change." In other parts of the country, it might be" inflation", "immigration", or even something as off-the-wall as "sin."

Regardless of what you think the worst problem is, it turns out that as the atmospheric content of carbon dioxide (CO2) increases, it's getting closer to what the level was in the Pliocene era, some three million years ago. And according to a recent report in Wired, scientists at Syracuse University have studied ancient leaf-wax deposits that tell them the American Southwest used to have significant monsoons (periods of extended rainstorms) back then, when CO2 levels were not much higher than they are now.

Even today, people living in the states of Arizona, New Mexico, and Nevada know that much of their sparse rainfall comes during the summer monsoon season. But the Pliocene monsoons were intense enough to make those regions as wet as northern Minnesota, land of a thousand lakes. That hasn't happened here yet, but if the scientists are right, things may be heading in that direction.

How does leaf wax tell us about rainfall millions of years ago? The wax is made from hydrogen in rainfall, and when it dries up, it blows away and gets deposited in sediment that can be dated accurately. And somehow, the scientists use these deposits to figure out how much rain was falling and at what time of year. It's not clear how quantitative this process is, but it's good enough to give the experts confidence that the Pliocene was a pretty wet time for the southwest US. And it may get that way again if current trends continue.

What strikes me about the article is not so much the facts of the matter, which are pretty indisputable, but the attitude toward the situation evinced by the researchers. On the face of it, you'd think that a forecast of more summer rains in regions that are historically dry as a bone would be welcomed as good news. But that's not the tone the article takes.

Instead, we hear that while some of the intensified monsoon rains will soak into the groundwater, much will run off into the watershed. And the built infrastructure—roads, bridges, storm sewers, etc.—may not be able to keep up with the more intense rain, leading to intermittent flooding. The lead researcher, Tripti Bhattacharya, herself says that another downside to more intense monsoons is—believe it or not—wildfires. More rain means more trees and shrubs, and more trees mean more wildfires.

In Act II of Hamlet, the title character says to his erstwhile friend Rosencrantz, ". . . there is nothing either good or bad, but thinking makes it so." Depending on one's point of view, the same scientific facts can seem to be either good news or bad news.

Professor Bhattacharya works in a funding environment in which climate change is the continuing crisis of the moment. Projects that relate in some way to climate change stand a better chance of getting funded than ones which don't. And so when asked about the implications of her research, it's understandable that she would come up with consequences that sound dire, because maybe then she'll get more money to find out exactly how dire.

I have no way of reading her mind, and perhaps such a characterization is unfair. But when the leaders of a culture unite around a pessimistic view of the future, it has serious adverse consequences. Young people raised in such an environment begin to wonder whether marrying and having children is pointless—or even going on from day to day, getting out of bed to face another day closer to the inevitable catastrophe that will happen if we don't revolutionize our economy to abandon fossil fuels yesterday, if not before. At best, it leads to an "eat, drink, and be merry, for tomorrow we die" attitude which bodes ill for the long-term survival of a culture, regardless of what the climate does.

On the other hand, the Wired article did point out one useful thing that can be done. As the climate changes, our infrastructure has to keep up with the changes. Civil engineering projects have historically based their designs pertaining to water and flood control on an unspoken assumption of uniformitarianism. That is to say, they take historical climate statistics and assume that what happens in the future will be the same, on average, as what has happened in the past.

There is a good and substantiated argument to be made that uniformitarianism in this regard is no longer useful. With numerous "500-year floods" happening a lot more often lately than statistics say they should, smart and forward-looking engineers should make efforts to forecast the long-term changes in climate that will result from the inevitable rise in CO2 levels that will happen in the coming years. That is how humanity has ingeniously survived all sorts of adverse situations in the past, ranging from the Ice Age to woolly mammoths and onward: by noticing threats and planning and executing countermeasures to survive them.

So the Syracuse University findings can be viewed either as more ammunition for a counsel of despair—one more reason to give up on the planet—or as useful information to use in adapting the infrastructure of the arid Southwest to deal with increased intensity of summer monsoons, which, if properly channeled into reservoirs and aquifer recharge zones, could be a very good thing.

Hamlet, the melancholy Dane, viewed Denmark as a prison. But we don't have to view the planet as a doomed spacecraft. It's a home that needs some fixing up, but that's how we've been surviving all along.

This article has been republished from the author’s blog, Engineering Ethics, with permission.


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