AoR 50: Cliff Mass, 2050 Climate in the Northwest

Climate influences vegetation, and a variable climate challenges land management. Cliff Mass, University of Washington atmospheric scientist, discusses climate drivers in the Pacific Northwest, how topography affects weather, whether 2020 wildfires can be attributed to global warming, and state-of-the-science approaches to modeling future climate. This tight episode finishes with Dr. Mass's recent analysis of climate out to 2050. 


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>> [Background music] Welcome to "The Art of Range," a podcast focused on rangelands and the people who manage them. I'm your host, Tip Hudson range and livestock specialist with Washington State University Extension. The goal of this podcast is education and conservation through conversation. Find us online at

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My guest today on the art of range is Cliff Mass. Cliff is a climatologist at the University of Washington, or maybe an atmospheric scientist. I think the extent of my brainstorming on these categories ends at meteorology, climatology and atmospheric science. Good morning, Cliff and welcome.

>> Good morning and I am an atmospheric scientist.

>> Great. How -- What was your pathway to becoming an atmospheric scientist? I tend to think that range land ecology is a bit of a niche field but atmospheric science seems to me kind of the same.

>> Well, I always liked weather, even for me as a young child, but I majored in physics at Cornell. And then I went to get my PhD here at the University of Washington in atmospheric sciences.

>> I'm a fan of weather. I find myself wanting to be outside whenever there's extreme weather. If it's 105 degrees in Ellensburg, I want to be out in it. And in the wintertime, I just assumed it'd be snowy and cold, then 35 and rainy. I know you get a fair bit of 35 and rainy in Seattle. Cliff, there are several climate features that I have believed to be unique to Washington State, which I find interesting having grown up in northern Arkansas, where there's not nearly so much climate variation within a really short distance. And so, I want to know if you can confirm or deny these rumored phenomena. The first is that I live in Ellensburg, which is about halfway between the Cascade Crest, which I believe receives 120 annual inches of precipitation. And then the Columbia River is about 30 miles to my east. And there they receive about 6 inches of precipitation. And I think that in that 80 miles, that represents the one of the steepest rain shadows in the continental US. Is that true?

>> It's a major one. But there's another one even closer to me and that's the Olympic Rain Shadow, where you have as much as 200 inches of rain on the upper windward slopes the Olympics and declining to around 14, 15 inches in Sequim, you know, in the order of dozens of miles away. So we have a really profound rain shadows here. We have a lot of enhancement of precipitation on the windward side of mountains, and it dries out rapidly as you get to the leeside.

>> Well, I didn't know Sequim receive that little precipitation. Well, that's related to my other question. I also think that we have the only temperate rainforest, true rainforest in North America, which is I think, defined by having more than -- 200 inches of annual precip. Is that right?

>> Well, I'm not sure about that but we do have rain forests on the windward side of our mountains, particularly Olympics, they're profound. I mean, there's some other places in the world have these midlatitude rain forests and that includes South America. So, you know, we're not alone but we definitely have ones here.

>> And then the -- from an agricultural perspective, we have a pretty warm climate for our latitude. It seems as if you follow this latitude to the east of us and every state east of us has much more severe cold winter temperatures. And the combination of the long growing season due to our high latitude in summertime and the relatively mild climate results in us, being able to grow a pretty wide variety of crops. And in fact, I think Washington State has the highest number of minor crops for which we are the leading producer in the nation. Am I right about the latitude of the mild climate?

>> Well, we have a mild climate and that's because we're downstream of the ocean. So in the Pacific Ocean, you know, keeps our climate mild. This would also be true in Europe, you know, where they're downstream of the Atlantic that's warm by the Gulf Stream moving water up there. So, you know, when you're on the western side of continents, you tend to be mild. As you go into the eastern side of contents, you get much colder and that's accentuated around here because we have these mountain barriers like the Cascades and the Rockies that keep the cold air from moving towards the coast.

>> Well, I'm accustomed to asking questions where I have at least some idea of what the answer is or a topic that I know something about but I'm -- I know almost nothing about this. So I'm interested in hearing from you. What are the major drivers of the atmosphere that brings about the weather in the Western US and in the northwest in particular? I tend to think in terms of, you know, vegetation types or biomes and those are clearly caused by the weather that we receive. But what are the things that result in, you know, in terms of the sources of moisture or the air masses that come across the west? Where does that diversity come from? And what are the sources of the climate, the weather we receive here?

>> Well, that's an easy question. There really, two major factors that control the weather and climate here. It's the Pacific Ocean which is relatively mild, and which doesn't change temperature very much over the year and the mountains. The mountains protect us from the cold air, the interior, and the mountains produce all kinds of local weather features. Everything from rain shadows and windward enhancement to convergence zones and you name it. So we, you know, our weather is really controlled by those two factors and everything else is detail.

>> Describe a bit what windward enhancement means. That means that on the side of the mountains that receive, the incoming wind and air masses, am I right that the air masses get pushed up into colder atmosphere and that causes precipitation.

>> So what happens is, you know, we have -- you have a mountain barrier. And if the air is coming from the west, as it does here, in the midlatitudes, the air is forced to rise by the mountains. And as the air rises, it goes from higher pressure to lower elevations to lower pressure, higher up and the air expands, and when it expands, it cools. And eventually it cools enough that it becomes saturated and you get clouds and precipitation. So the windward side is the side of the mountain barrier that's facing the wind. So that's where the air goes up, you get clouds and precipitation. Then as the air goes across the crest and down, it tends to sink. It's going from lower pressure to higher pressure. It's getting compressed. When the air gets compressed, it warms, the relative humidity tends to drop. The clouds evaporate and you tend to have a rain shadow. So windward side is facing the winds, leeward side is the opposite side of the wind. And that explains a lot of the precipitation variation here in the Northwest.

>> Right. One of the major features in range land ecology in the Western US is the fact that not only as much of the west relatively dry, but that annual precipitation is fairly variable from year to year. And therefore, net primary production in plant communities is -- can be pretty variable and somewhat unpredictable. Because of wintertime -- because of our winter precipitation pattern in the Pacific Northwest, some of that unpredictability is reduced. But this interannual variability in precipitation has really been accepted as a major driver of vegetation change that often is more significant than management. In other words, if you look at landscape change over time, most of the changes can be attributed to climate variables rather than management variables. And one of the predicted effects of climate change for this geographical region is increasing variability from what is already somewhat high variability, at least on the east side of the coastal ranges. What do you say about that?

>> Well, first the variability here in the West Coast depends on your latitude. The precipitation is much more variable as you go south into California, because they're depend on getting these intermittent atmospheric rivers that drop a lot of the precipitation in a limited number of days. So variability is much greater to the south. It's not so much up here, where, you know, we -- if we don't get atmospheric rivers, we get other storms. So, you know, it tends to be much less variable up where we are. I think it's really uncertain whether global warming is going to change variability much in terms of our meteorology. So I think the jury is still out about them.

>> Well, recently, and by recently, I mean, maybe the last 5 to 10 years, it seems that the news media regularly attribute every weather event or every weather phenomenon that seems at all unusual to climate change. And it where we live in a place that has vegetation types that are prone to wildfire in weather the supports wildfire, it seems a little bit misleading to blame any wildfire in deserts and dry forest types on climate change. I, you know, even talking with our farmers and ranchers on this side of the state. They believe that they see climate changing. So my question is, is what we're experiencing now in terms of both weather and weather related events like fire within the historic range of variability or is there enough, what we might call anomalous behavior in the frequency of fire or the size of fire or the severity of fire, wind events, you know, summertime highs to say that we're currently experiencing the changes associated with global warming.

>> Right, we have to separate out fires from weather. They're not the same thing. The frequency of fires can vary by a number of reasons or the fact that we've suppressed fire in many locations for almost a century. The invasive grasses, many of them very flammable that it moved in, the fact that more human beings starting fires. So there's all kinds of issues about fires that are independent of weather and climate. So you got to be very careful about, you know, assuming any kind of change in wildfires has anything to do with weather and climate. I think the media tends to be a little bit over exuberant about blaming everything on climate change. Now, global warming is a serious issue. But it's one in which the major warming is ahead of us. Right now, the Northwest has warmed up maybe 1 or 2 degrees Fahrenheit over the last 40, 50 years and, you know, we could, of course, a significant portion of that. But, you know, our climate change here it's lessened, it's weakened, it's delayed, because of the ocean. The ocean is a tremendous flywheel that slows things down. So I think, you know, there have been some changes due to climate change, I think there's been due to human caused climate change and it's probably a little bit of warming. But I think we have to be extremely careful before blaming extreme weather events or other changes on climate change.

>> One of the more obvious recent weather events that has drawn quite a bit of commentary about climate change is the fires in California, and to a lesser degree, at least in terms of media coverage, the ones in Washington, what are your thoughts on the drivers of the California fires this year?

>> Right. And I've actually been doing research on this area. And I've published papers on the Wine Country fire and the campfire and I'm working on the some of the others. I think in California, it's a very mixed bag. I think the fire suppression over decades has been important. I think the basic grass is important. I think that human ignition of fires is very important. A lot of the fires are being caused or are ignited by power lines. So I think you know, even in California, it -- there's no way one can say that, you know, most of the increase of fires is due to climate change. And one thing I should point out is that fire is a natural part of the ecosystem in the west. And in many locations, fire would burn every 10 or 15 years, especially in the eastern slopes of the Cascades or in the Sierra. So fire is normal here. And what wasn't normal is the fact we suppress fire for such a long period of time.

>> What about the Washington fires? This year, most of the fires were on non-forested plant committee types, what I would call mostly range land fires. And I want to say you have written that that was driven by easterly winds. Can you say more about that?

>> That's right. Here in Washington State, almost all the fires that we had and the catastrophic burning was the Labor Day event on at least seventh and eighth in that period of September. These were mainly grass fires and grass fires generally have very little to do with climate change. In this case, it had everything to do with strong winds and we had record breaking winds that pushed into the area from the north to northeast. And those I think are -- were the key factor in both igniting the fires and then causing them to explode and move very rapidly.

>> You recently did a fresh analysis of climate projections out to 2050 using a number of models all put together in what I think you call an ensemble. What did that turn up in? Can you describe that methodology?

>> That's right. I'm involved in an effort to basically try to look forward to the year 2100. What would -- What will global warming do to our region? And we're making the assumption that CO2 in the atmosphere keeps on going up as fast as it has been. So, you know, mankind does nothing. What does it look like and we've run high resolution weather forecasts models driven by global climate models for 130 years. And so what we have found is that there will be warming that actually will speed up a bit and during the century. So the region will warm up and will be considerably warmed up by the end of this century. A snowpack will drop substantially. Precipitation won't change that much. We'll get a little bit wetter. But we think that the heaviest precipitation events will get heavier that's something we do expect in global warming. So we've basically gone through the -- in this exercise and found what we -- what global warming implies for the whole region over the rest of the century.

>> In the south, they would say that there's 100 different ways to skin that cat. How did you go about that analysis?

>> Well basically, you know, we have a lot of experience with weather forecasting models and we ran high resolution weather forecasting models for 130 years, driven by the global climate models. And we did this many times with different global climate models to see what signal is common to all them. And so, you know, we've done this and what we've done is different than other people because we ran the simulations that have a high enough resolution to get the rain shadows, to get the windward enhancement, to get the gap points. And so, you know, we have shown that the planet -- the planet's warming up is happening here, too. It's a little slower here because of the Pacific Ocean but we will warm up the century. And issues such as the snowpack, you know, snowpack will decline and that's of concern to agriculture. Precipitation will not decline, that's also important for agriculture.

>> Yeah, on that note, what do you see as some of the alternatives to mankind does nothing both from a, you know, a general societal perspective and also from an agricultural perspective, what can we do to mitigate this?

>> Well, we can do a lot. I mean, first, even if we keep on putting CO2 in the atmosphere, we could do a lot of adaptation. So we can prepare ourselves to deal with these issues. So for instance, be less snowpack in the mountains but we'll have as much precipitation, we could build more reservoir capacity, particularly on the eastern side of the Cascades. And some people have already suggested this, the [inaudible] project is an example. So we can store more water and therefore have the water we need for agriculture. So there's that adaptation. We can make sure we move away from being right near the coastline with coastlines low as sea level rises. So, there's a variety of adaptation things we can do, probably the most important one is the forest. We could manage the forest to restore them to what they were like 150 years ago. So get rid of debris, bring back fire, thin them out. So bringing the forest back to what they were naturally, that would go a long way to stopping catastrophic fires. And then of course, there's the issue of CO2 in the atmosphere. And, you know, quite frankly, I'm optimistic about that. I think we could use nuclear power, efficient and later fusion to supply much of our energy that we need. And then, we -- once we have a lot of energy from nuclear energy, we could actually take the CO2 out of the atmosphere, there's a technology called sequestration that allows us to do that. So I think that global warming actually is a technical problem that we can probably solve technically. And in the meantime, we can do a lot of adaptation to protect us against, you know, some of the impacts that are that are occurring now, and during the next few decades.

>> I like it. Where can people read some more about what you're doing if they're interested in learning about some of these topics in more detail?

>> [Background music] Well, I do describe, you know, some of some of the work in my blog, so cliffmass lowercase And, you know, some of the things I'm talking about are already in the published literature. So there's papers you can search for and you can read about this kind of material.

>> Well, Cliff, I appreciate your time today. It was great to have you on and I wish you the best.

>> Great, it's good talking to you.

>> Thank you for listening to "The Art of Range" podcast. You can subscribe to and review the show through iTunes or your favorite podcasting app, so you never miss an episode. Just search for Art of Range. If you have questions or comments for us to address in a future episode, send an email to For articles and links to resources mentioned in the podcast, please see the show notes at Listener feedback is important to the success of our mission. Empowering range land managers, please take a moment to fill out a brief survey at This podcast is produced by Connors Communications in the College of Agricultural, Human and Natural Resource Sciences at Washington State University. The project is supported by the University of Arizona and funded by the Western Center for Risk Management Education through the USDA, National Institute of Food and Agriculture.

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Mentioned Resources

Cliff Mass's popular blog is at
And his book "The Weather of the Pacific Northwest" is available at…ass/dp/0295988479.

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