The West Coast is facing another year of extreme drought, and water managers are deciding where slim resources should go based on predictions from climate scientists. Andrew Schwartz is one of those scientists. He manages the Central Sierra Snow Laboratory for the University of California Berkeley. He says researchers across the West are using outdated models and measurements to predict the drought. The result is a poor understanding of the relationship between how much precipitation falls, and how much water is actually available to use. He joins us to share more about the details and implications of his work.
The following transcript was created by a computer and edited by a volunteer:
Dave Miller: Even after recent rain and snow, the western US is still facing another year of extreme drought. This week, Governor Kate Brown declared drought emergencies in four more Oregon counties. That brings the total to 11. Water managers in Oregon and across the west we’ll have to decide where slim resources should go. Andrew Schwartz says this is a problem. Schwartz manages the Central Sierra Snow Laboratory for the University of California at Berkeley. Schwartz says these managers are relying on outdated models and measurements in their water allocations. Schwartz wrote a recent op-ed in the New York Times about this. I talked to Schwartz earlier this week. I had him give us a big picture look at the West as a whole.
Andrew Schwartz: Well, the conditions in the West are basically what we’ve been seeing for the past two to two and a half years; we’re going into another year of drought. And even though we here in northern-central California and even a few other parts of the west have gotten some precipitation, it’s not necessarily enough to pull us out of that drought. And so unfortunately we’re looking at another year of dry conditions and potentially fires.
Miller: A very snowy April in Oregon and Washington has boosted snowpack here a lot over the last couple of weeks, but that’s after a very dry beginning of the year. How many average or I should say above average seasons in terms of precipitation would we need to have in order to break this drought?
Schwartz: That’s kind of a difficult question because there’s no golden answer here. Of course it matters how much rain and how much snow we get in each of those seasons. If I were kind of spitballing and just coming up with an idea, I’d say we’d need at least 2-4 years of above average precipitation depending on how much we actually saw. If it was at average, maybe slightly above average, we’re looking at four more years. If we have just a couple absolutely crazy years, then maybe we get out of this in two, but it’s really not something that one or two events will bring us out of.
Miller: In your recent op-ed in the New York Times, you focused on a couple of things, including the longer term–in the last couple of years–effects that the drought has on land and the way that that can sort of reverberate even when there is more precipitation. So let’s take some of these things one by one. How does an extended drought affect the land itself in terms of what happens later when it rains?
Schwartz: Yes, one of the biggest things that we think about when we think of extended drought and its impact on the land is soil moisture. I’m an atmospheric scientist by trade. I’m used to looking at the sky, but with soil moisture becoming even more important than it has been, I think a lot of us in meteorology and in snow hydrology are now looking down at the ground and looking at our soil. One of the issues is that when we have these extended droughts our soil dries out quite a lot and that means that any new rain or snow that comes in can immediately be soaked up by that soil and reduce the amount of it that’s going into our streams and then our reservoirs because again that soil is just a big sponge and it wants that moisture, too. So that’s kind of the first issue that we see is this response in our soil that can effectively keep any new precipitation out of the streams. The second is that we have these large fires that have been ravaging the West for the past few years and even back to a decade or two. And the problem is our forests dry out, we have dry soil, which then makes fires much more likely. And then at that point, of course the fire goes through, alters the trees and the branches and the canopy that we have that protects things like our snow and then our snow melts faster, which in turn makes our soil and the rest of the forest dry out even faster again the following year. So it’s this kind of continuing cycle with these large droughts like this that just keep creating problems.
Miller: It really seems like one more negative feedback loop of a kind that we’ve come to here is sadly a part of climate change in this case. Climate change worsened fires or drought making it harder for aquifers to be replenished or for surface water to actually happen. Is that a fair way to put it?
Schwartz: That’s absolutely correct. All these processes have existed in the past. But the variability in them from year to year or the droughts from year to year haven’t been as extreme because we see the severity increasing with anthropogenic climate change. So that’s completely correct.
Miller: One of the biggest points you make in your recent op-ed, is that the models that governments are using in terms of water in the West have not kept up with our current reality, let alone our future. What exactly are these models used for?
Schwartz: So there’s a couple different types of models and I’m not going to go into them too much. But the first is basic statistical models which most of us have probably done on things like Excel where you see a bunch of data points and you fit a line to it. So X amount of snow means X amount of water and that then it’s pretty easy to forecast. But they’re very simple. The other type of model is what we call a process driven or physical model, which actually includes all these kinds of nasty physical equations and things like that, to model things like evaporation and the snowpack processes themselves. And one of the problems is a lot of these models were developed several decades ago, and especially with the statistical models, we see that those may represent conditions that no longer exist because our climate has changed. With the physical models, those ones generally tend to keep up because they don’t look at the relationships as much as the processes themselves. So those ones are doing better and a lot of those are currently being run in places like the River Forecast Center that are run by the National Weather Service. But, like we just spoke about fire, it’s not bringing into account those large scale land cover changes. And so ultimately,
they’re not necessarily keeping up with what we’re seeing as you put it.
Miller: But what are the repercussions of that? If, as you’re arguing, modeling hasn’t kept up with reality, why is that a problem beyond a laboratory?
Schwartz: Well, realistically, when you have these models that may not completely synched into reality, you can get some pretty bad results out of them. The saying is garbage in garbage out. Right? So if you don’t have the right data going into them or the right processes within the models, they’re not going to give you the best, the best data out and these models are all used for things like expected inflow for our reservoirs so that water managers can then make decisions about how much water to let out or how much water to retain. And so the problem is that if these models overestimate for instance our water that’s going to be coming into the reservoirs, we may be releasing water that we don’t have the opportunity to waste or to release in the quantities that we are. So that could mean less water for everyday people, less water in your taps, potentially even in a worst case scenario and a bad drought, even entire towns going dry. So increasing our ability to measure and model these processes in our water is so critical to make sure that there’s enough water for everyone.
Miller: Although that last point seems like maybe the most crucial one because it seems like better models could give water managers a more clear eyed picture for, say water allocations, but they’re not actually going to create more snowpack or or more rainfall, they’re not themselves going to lead to more water being in a reservoir to begin with, just a more accurate picture of the total water year. Can you paint us a picture of what you think the West is actually going to look like in the coming decades in a good year or a bad year?
Schwartz: Yes, and and everything that we’ve talked about to this point has been very kind of modeling, measuring scientifically-driven, but there is a large policy and engineering component to this that we haven’t addressed right. As you said, we can’t create more precipitation, not in the quantities that we would need it. And so ultimately, that means that all we can do is our best at managing the water that we do have. But with our increases in population, with the ever present drought worsening and temperatures increasing, it puts all of the western US in quite a bind because ultimately, in the next several decades we’re not going to have the water that we need for everyone on the West Coast unless we make dramatic changes. So in an optimal year in the future, we might get several big storms, we might fill up our reservoirs and then we’re good for a couple years. In a bad case scenario with drought, which is expected to become increasingly likely under climate change, we can and this is the worst case scenario again, but we can have large migrations of people that are forced to leave their homes. Nobody wants a house that doesn’t have water and if we don’t start planning now for the eventuality that we need more water, that’s what we’re potentially looking at.
Miller: Large migrations away from, say Phoenix and Las Vegas and LA?
Schwartz: Exactly, yes, large migrations. And the larger cities have the opportunity to potentially implement some better policies and things like that to get water to them. But a lot of these smaller towns are going to be the ones that are first hit with those types of issues, with those types of water shortages.
And so as a result, yes, it’s going to be around some of those larger cities too, but it’s going to be the smaller towns that are kind of the canary in the coal mine. Are we having to ship in water? Are you now having to leave your home? And if that’s the case, where are you going?
Miller: Do you see any way out of that?
Schwartz: I do. I’m not an engineer and I don’t know all the numbers, but I can tell you that one of the bad words, there seems to be here in the West is desalination and I’m not entirely sure why that is. There is this notion that it is very expensive and that can be the case but when you consider the cost of what’s at stake, it’s relatively small in comparison. Now, the other thing is there seems to be this, oh, desalination technology hasn’t caught up to present or it can be an environmental issue. And the environmental issue is that the true one, you have all this saline or just raw salt that you have to find a place for and you don’t want that to impact the environment, but ultimately the technology has come forward. I did my PhD in Australia for four years and they have successfully implemented a lot of these large scale desalination plants that have the opportunity of providing enough water for most of their 25 million plus population. So in my opinion, this is definitely a technology that we should be looking at much more closely because when we don’t get the natural water that we need, we could potentially augment it using these types of systems.
Miller: Andrew Schwartz, thanks for joining us today.
Schwatz: Thank you so much for having me on.
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