Wildfire Presser Full Transcript: October 18, 2017


Dr. LeRoy Westerling – Professor of Management of Complex Systems and Co-Director of the Center for Climate Communication at UC-Merced

Dr. Linda Rudolph, MD, MPH– Director of the Center for Climate Change and Health at the Public Health Institute in Oakland, CA

Dr. Bill Stewart – Cooperative Extension Forestry Specialist at UC Berkeley in the Department of Environmental, Science and Policy Management and Co-Director of UC Center for Forestry & Center for Fire Research and Outreach

Moderated by Emma Stieglitz, Co-Director of Communications, Climate Nexus


Emma: Alright, so we'll open up the call. Good afternoon everybody and good morning for everyone who has joined from the west coast. Welcome to this briefing on the wildfires in California. I'm Emma Stieglitz, I'm going to be moderating today and I just want to remind people that the call is being recorded, so if you want a copy afterwards, follow up with me and I can email you the file.

So just to recap, according to the news this morning there were new fires reported yesterday in California. They forced about one hundred fifty people to evacuate and the fire which is being called the Bear Fire has so far destroyed about two hundred fifty acres. That is, of course, after a group of fires in the wine country region killed more than forty people, destroyed more than fifty five hundred homes, burned about two hundred thousand acres, and displaced about one hundred thousand people. Fire season in California has been getting longer in recent years and 2017 is already proving to be among the worst on record. So we thought it was prime time for a press briefing about this.

Today we're going to hear from a great panel of experts about these fires. I’ll introduce them now. Our panelists are Dr. Leroy Westerling. He's a professor of management of complex systems and the co-director of the Center for Climate Communication at the University of California at Merced.

Our second speaker will be Dr. Linda Rudolph, who's the Director of the Center for Climate Change and Health at the Public Health Institute in Oakland.

And our final panelist is Dr. Bill Stewart. He is a cooperative extension forestry specialist at the University of California at Berkeley in the Department of Environmental Science and Policy Management. And he's also the co-director of the U.C. Center for Forestry and the Center for Fire Research and Outreach.

There will be time for Q and A after the speaking line up has concluded. If you've joined on line you can ask a question by clicking the ask a question button or it may look like a raised hand button. That will put you in a queue and I’ll read your question aloud to panel. If you've joined on the phone you'll need to email me your questions, my email address is listed on the media advisory and I’ll re-prompt for questions at the end of the speaking order. So without further ado I just want to turn it over to our panel. So first of all start with LeRoy Westerling.

Dr. LeRoy Westerling

It is a pleasure to be here. I wanted to also give a shout for the California/Nevada applications programs, so in addition to the position at UC Merced, I’m part of the NOAA funded Climate Assessment for California down in San Diego. And it's been a resource for two decades now for people in the state and also for people in Nevada who need help with climate information regarding fire, but also flood, drought and other impacts in the region.

So there's a shifting range of perspectives to look at for this in terms of a time horizons for thinking about climate fire. In the really short run, this is to a Mediterranean climate at this time of the year where we're following a long summer dry season, and we can get these winds, these Diablo winds in Northern California and the Santa Ana winds in Southern California, that can fan fires once ignited and these coastal regions with a lot of chaparral and grass have plenty of fuel it's usually pretty dry by this time of year and given the proximity to lots of population centers there are a lot of human fire ignitions. When you combine that al together, this is a peak opportunity time in October for some of these big fires to occur. And they can have a lot of impacts on people because there's close to where where a lot of people live in California.

But then we have—if you step back a little bit—we had a really wet winter following a multi-year drought and that was a really significant drought, maybe one of the most severe in the last thousand years. And so when you look at that we have a lot of additional fuel created by the wet winter that cures out during the summer dry season, and we have a lot of standing dead fuels from vegetation that was killed during the drought.

If you step back even more and you ask, what about climate change? Well, for decades now we've had average temperatures in the long run that have been warmer than the historic temperatures that we use as our baseline for comparison. And warmer temperatures means more evaporation, more evaporation from the soils, more evaporation from the fuel. And cumulatively over time, it can have a profound effect on the landscape, and on the flammability of fuel, and on the availability of fuel. So you think about in a wet years you have warm temperatures, like this year we had very warm temperatures in the spring and summer, that means more evaporation in the wet years, that means less moisture to carry over. It also means that the fuel after a very wet winter, they can dry out especially in these coastal counties like Napa and Sonoma by the time you get to to the fall fire season. But it also means that your droughts are more significant, because you have less moisture carrying over from the wet years and you have warmer temperatures during the drought. So all of that together really sort of turns up the dial a notch on the extremes that we can experience in terms of drought and in terms a wildfire in the region. And I’ll pause here for a follow-up question.

Emma: Thank you LeRoy. So it looks like Craigmillar from K.Q.E.D. has a question which is: what actually causes Diablo winds?

Dr. Westerling: When you get into the fall your rate of temperature change at the coast, where you've got the ocean, which is like a reservoir that retains heat, is different than the temperature change inland. And that increased temperature gradient from the coast to the interior drives these wind events. And then because the air is descending from the interior to the coast and in between it can pass over a few mountain ranges that really results in it being much drier. So you have really low relative humidity in these winds and they’re increasing in intensity at this time of year and we haven't had a significant rainfall yet to really put an end to the fire season, so that overlap between the end of the summer dry season and the beginning of this intensification of this wind regime gives you a peak opportunity for these big fires that can spread really quickly.

Emma: Alright great. Thank you Dr Westling. Does that conclude your remarks for now, again we're going to get to Q and A after the speaking line up is over, but that one seemed useful to ask right away.

Dr. Westerling: Yeah, I mean there's a lot of different things I can address in terms of the length of the fire season, and things like that, but I’d like to give the other speakers an opportunity to weigh in.

Emma: Alright, sounds good, thank you so much. So our next speaker will be Linda Rudolph. And I’m just going to make sure you’re unmuted. You should be able to go ahead now.

Dr. Linda Rudolph, MD, MPH

Hi, I'm Dr. Linda Rudolph. I'll be speaking about how wildfires impacts health, who is most vulnerable to the health impacts of wildfires, and a little bit about what we can do to protect health. First wildfire smoke is a complex mixture of gases and particulate matter. The particulate matter in smoke, especially the very small particles known as PM2.5 can get deep into the lungs, and it can cause exacerbations of asthma, bronchitis and cardiovascular disease. Wildfire smoke exposure has been associated in numerous studies with increased premature deaths and with increased hospitalizations for asthma and chest pain. And smoke can cause breathing problems even in healthy people.The plumes of wildfire smoke can travel very long distances so thousands of people even quite distant from a wildfire may be affected by the smoke. The risks of mental health problems especially depression and post-traumatic stress disorder after a wildfire are also high and often not discussed as much as the respiratory effects, so they are important to keep in mind. And for people that are in burned areas, I think it's important to note that ash and debris can contain a lot of toxic substances such as asbestos and heavy metals.

Water may be contaminated. For example they did issue a boil water order in Napa County during the fires and even canned or bottled food that's been exposed to a wildfire may be unsafe. And wildfires cause very significant disruptions to our health care system. The Sonoma fire caused the evacuation of two major hospitals for many many days, also several clinics were burned, skilled nursing facilities had to be evacuated. Many of those who were evacuated, one hundred thousand people were evacuated, lost their medications, and pharmacies in the area are still struggling to fill prescriptions, especially for respiratory illnesses.

Who is most vulnerable to the health impacts of wildfires? The elderly, especially people with chronic heart lung disease. Very small children are especially high risk from smoke and particulate matter, and again children with asthma. Young children are also at a particularly high risk of psychological distress. Outdoor workers are at risk, especially if they have to continue joining heavy labor in areas with bad air quality due to smoke plumes. People living in poverty who are less likely to have disaster insurance or health insurance and have fewer resources with which to cope when they lose their homes or medications or jobs. And of course our courageous firefighters who literally put their lives at risk to save lives and homes. They’re at risk, not only from smoke, but also at risk of severe injuries, burns and heat illness because these wildfires burn so hot.

Fortunately, there's a lot that we can do to protect health from the impacts of wildfires. In the short term, it's really important for people to pay attention to the air quality index. And if the air quality is poor, to stay indoors in a building with filtered or recirculated air and closed windows. If you have to go outside, use an M95 respirator, not a plain paper mask. And pay attention to information from your local Health Agency about boil water orders or instructions about touching ash and debris and air quality information.

It's also important that we plan to reduce harm to human health from future wildfires. For example, with land use policies that limit development of the wildland/urban interface with community design that makes sure there are adequate exit routes. With warning systems, with building codes that require flame resistant building materials in fire prone areas. And we need to build resilience in our health care system so that we make sure that our hospitals and clinics are the last building standing and that we minimize disruption to health care services when people need them.

This has been a really tragic wildfire. And along with all the recent hurricanes it's another demonstration of the fact that climate change is already threatening our health and safety. We certainly need to prepare for the impacts of climate change but it's also critical that we act to reduce emissions of climate pollutants so that we prevent even more devastating climate change impacts on our health and the wellbeing of our communities and our children. And I'll stop there.

Emma: Alright thank you Dr. Rudolph. Finally we’ll hear from Bill Stewart.

Dr. Bill Stewart

Dr. Stewart: I just want to say, you know California has a real wide mix of grasslands, shrub lands and forest, and they've always burned and they’ve burned a different very different rates. But in our research, you know, we've been seeing clearly that the rates of these areas have gone up by 25-50% in the last three or four decades. So they’re are a number of causes and climate change is definitely one of them across all types but there's also a lot more vegetation on a lot of slopes. And that's also increasing the burning, especially on federal lands.

But you know I think when we talk about the fires in the wine country and the ones in Santa Cruz, the most costly fires in terms of financial cost and public health are the ones that are burning in private lands around where we have lots of houses and businesses. And a lot of those are not, you know, the forest fires that might get on the television when we look at Idaho and Montana, but it's really grasses, shrubs, and trees that are all dried out and they're all, as Leroy said, they're all burning, and they're going to be burning differently. Probably the trees are what created the embers that were able to fly across 101 and burn down the subdivisions, but clearly all the vegetation, grass, shrubs, and trees are all burning, and that's what's making this fire very difficult to put out, and it's producing lots of smoke that’s impacting the public health of everyone in that area.

I think one thing we’ve seen is that California is probably under investing in how we're doing some strategic work on reducing the amount of vegetation that can burn, so that when a fire comes it's going to be a lower intensity than some of the fires we've been seeing now. It's a challenge because removing vegetation also impacts wildlife habitats, recreational opportunities, it costs money, but we're really going to have to figure out how to do more strategic vegetation management around, especially around communities because you know the cost, especially the public health costs have been very high for this. If you have any other questions, maybe we can follow up in the Q and A.

Question and Answer Portion

Emma: Alright. Well thanks so much Dr. Stewart. We will just turn it over to Q and A at this point, and I've got one in the queue already that I'd like to ask, and then I’ll reprompt people for how to ask questions afterwards. So again, this one is another question from Craig Miller, and he asks:

What long term trends have been identified that make the climate wildfire connection. Can we say that we would expect longer droughts, etc. to increase fire activity? What have we actually observed? And what is the smoking gun, so to speak?

Dr. Westerling: This is LeRoy, I’d like to take a stab at that. There's a lot of a ways you can look at this. One is looking westwide at forest versus nonforest areas on federal land. The forest areas area burned has been increasing over the 1970s-early 1980s baseline, that’s when the dataset starts, 390% per decades over that that original baseline and the non forest area has been increasing by about 65% per decade.

So, forests clearly are more sensitive to temperature changes from our evolving climate then say, lower elevation chaparral and grasslands. And that kind of makes sense. This is an arid region. The places where you have the most moisture and sustained large forest area are basically higher elevations and higher latitudes, where you get more snow, more precipitation overall, and more of that snow, and that snow carries the moisture over into the summer dry season, and helps sustain the forest.

So part of the smoking gun that we see is that the biggest increases in forests, in fire, have been in forests, and the biggest forest areas that have increased have been in places like the Northern Rockies, where snow is a really important part of the annual water cycle and you get a really non-linear response, because most years maybe you wouldn't have enough of the dry season to really get the fuels dry and have to burn, and the warming that we've seen to date has been enough to kind of kick it up into a new regime where most years you actually can get significant fires now.

And interestingly, most of the increase in burn area has been in places where forests have not been greatly affected by fire suppression, so suppressing fires year after year and land use changes that also help to suppress fire can lead to increased fuel loads, especially in places like say mid-elevation Sierra Nevada or in the Southwestern forest, and those are not the places where we’ve seen the largest increase in fire with warming temperatures, it's been in places like the Northern Rockies and more recently the Northwest that have been really strongly associated with the warmer temperatures and earlier spring and where we've seen big increases in fire season lengths.

And just to give you some numbers, so looking at forest areas, this last decade the northern Rockies increase over the baseline is close to 3000% increase whereas in the Sierra Nevada it’s more like a 300% increase. The Northwest, just under 5000% increase over the 70s and early 1980s. So there have been very dramatic increases in areas burned but it's been very highly variable across the forests, depending on what their background climate looks like before we started warming it up.

As for the length of the fire season, it’s a very similar sort of thing, so we've had over the whole western U.S. the fire season length increased from 138 days back in the 1970s to 222 days in the last decade. And the Sierra Nevada for example, by comparison went from 65 days to 140 days. So the fire season has been increasing everywhere but the length has changed quite a bit more in some places like say the Rockies than it has in, say, the Southwest.

Emma: Thank you Dr. Westerling. Are there any other panelist who would like to answer that question? If not, we've got several more in the queue.

Dr. Stewart: This is Bill Stewart. I just want to point out that, for California residents, it’s the shrub lands which have always been the most prone to fire. They burn an average of one to two percent a year, as a probability. And I think what we're seeing is that Northern California, as it dries out, is acting more like Southern California. These fires were having would not be that unusual for Los Angeles or San Diego County but you know it's becoming more and more common here that we're having fire weather, hot fire weather, going away way into the fall. I think that's really an example, climate change is making it seem like we're living one or two counties south every decade in terms of fire behavior, the weather.

Emma: Okay, alright thank you. so we've got several questions, the next one comes from Deborah Kahn. She’s with E&E. She writes: “Dr. Stewart, can you say more about that finding about rates of burning; was it 25-50% more over the past three to four decades and what area is that in?”

Dr. Stewart: So that's a study we're just right now we're on getting it published, but we looked at grasslands, shrub lands, and forests, and it varies by ownership, but you know the rains in every one of those types was somewhere between 25 and 50% more fires whether it's private shrub plans, federal forests, private forests, all of them all of them have increased. And there's a variation, but the pattern has been consistent across all the vegetation types we have in California. And that was just looking at the acres burned from the historical fire perimeter record we have that goes back to the 1950s.

Emma: Great thank you. Okay, our next question is from Leah Russell. She's with the American Prospect. She writes: “If we know wildfires will be more frequent now, what does this mean for California; what will be the state's response going forward?”

Dr. Stewart: This is Bill Stewart, one of the things the state is developing what's called a vegetation treatment plan, so they can actually spend state dollars in reducing some of these fire risks, especially around communities. But those are major environmental activities, so they need to look at the impacts of those, maybe a fire risk reduction and possibly a public health increase, comparing that to how that’s going to affect wildlife habitats, especially for endangered species, how’s it going to affect recreational opportunities, how much is it going to cost. So the state is actually trying to get those programs to work together, so it isn't just about risk reduction, trying to remove all the fuel, because the reason it’s there is because people like seeing green landscapes around their neighborhoods. So they need to develop that balance so we can actually invest more in actually reducing some of the fire risks that surround our communities.

Dr. Westerling: This is LeRoy here too. So California has been very proactive in developing resources for informing decision making for adaptation. We're in the midst of our fourth statewide climate assessment funded by the state legislature and by the conference of energy commissions. And it looks at climate change impacts on a broad array of sectors including wildfire. So we have prepared simulations of average fire events but in extreme events, so we have a huge library or simulations of different scenarios for future climate, but also fuel management and population growth scenarios and development footprint scenarios. Some of these are available on the Cal Adapt website for the state of California Climate Assessment and that information being used by different groups around the state who are looking at the risks to different types of energy infrastructure, transportation infrastructure and also housing insurance markets. And then we have a project funded by the University of California, a multi-year project that looks at climate change and public health and the big part of that is looking at how changes in wildfire that we project for the coming decades will affect emissions particulate matter and how that will affect public health around the state. One of the biggest changes that we see with with climate change projections for wildfires is that, historically, the biggest source of wildfire emissions that might affect a populated area of the state were from Santa Ana wind driven wildfires in the fall in Southern California and the Sierra Nevada forests and the fires in those come to dominate the statewide particulate budget in the summertime by mid century, far exceeding what was projected for Southern California.

Emma: Thank you so much. So I want to take a question that was sent in over email. Our next question comes for Alastair Bland with the East Bay Express, and he writes: “Can we expect policy changes that limit building and development in the wildland urban interface, and will this be possible in California where the human population is growing rapidly and the landscape is becoming more fire prone?”

Dr. Stewart: This is Bill Stewart. You know one thing, much of what we’ve seen in terms of the house loss are houses and businesses that were built a few decades ago when the fire building stands were a lot more lax, I would say. And new standards actually, the truth is if they are really built high standards, a lot of new homes could actually withstand some of these fires, and that’s probably not going to change. But in addition, I think the bigger change is having to think about vegetation management on the broader landscapes, which includes everything from private land to open space districts and state parks. Putting all of those together, thinking about this as a large area is going to require crossing regulations, private lands, state lands, and that planning issue hasn't really been done as well to date, and I think we're going to see a bigger push to integrate East Bay regional parks, and private lands, and state parks as one fire prone entity.

Dr. Westerling: LeRoy again. The majority of the housing stock say mid-century has already been constructed, or will be constructed in the near term, so the more we control how new development is done, but also how people retrofit existing developments, can really shape the state’s economic vulnerability to changes in wildfire in the coming decades. And that's an important aspect of this outside of attempts to mitigate climate change by reducing the its rate of change.

Emma: Alright great. So our next question comes from Monica Woods with ABC10, she writes: “Given the increase in housing development and areas prone to fire danger, not to mention the trends showing even higher risk for catastrophic fires, do we need a similar system to tornado warnings for fire warnings?”

Dr. Stewart: This is Bill Stewart speaking, I think this issue of getting warnings out to people with reverse 911 calls and actually having it focused so that you don't have everyone that may not be in the burn area flooding all the roads and then having people in their cars during the fire is going to be a major issue after this fire is how to actually do safe evacuations at a very large scale that don't block the roads. And I know that's been probably one of the largest cities from a public safety standpoint, these have to be done much faster than hurricanes, for which we have days of warning. With this, they basically had an hour's warning. But this clearly we're going to see a major push to try to understand how to do this better in the future.

Dr. Rudolph: This is Linda, I think it's also really important that we pay attention to particularly vulnerable groups like the elderly, those with limited mobility, those with hearing impairments and so on, as we consider what the shape of those early warning system is.

Emma: Thank you Linda. And thank you Bill. Alight, moving on to the next question, this one is from Georgina Gustan, she is with Inside Climate News, she writes this question is for Bill: “Can you explain in more detail the study you mentioned that shows that the rates of grass/shrubland burning has gone; was it 25 to 50%, over what period?” Actually I think we may have answered this already but if you just want to remind very quickly.

Dr. Stewart: You know this was a study done by Carlin Stars, a Master's student here, and we looked at basically the probability decade by decade of fires in grasslands, shrub lands, and forests, and so right now they are somewhere between 1 and 2% for grasslands, and so a few decades ago it was more in the 0.5 to 0.75% a decade, and so we did that by each type because grasslands can burn a lot faster, because the fuel is always dry. But it isn't nearly as severe and as dangerous as when a forest or a shrub land is burning, because there is just less fuel per acre that catches on fire.

Emma: Thank you. Our next question comes from Chris Roberts at Curbed San Francisco, and he's got several questions, but the first one I'll ask is: “What is the likelihood of a wildfire of this magnitude hitting an even more heavily populated area than Santa Rosa such as San Francisco or Los Angeles like the Oakland Hills wildfire?”

Dr. Stewart: The fire behavior of the wine country fire is actually very similar to the Oakland Hills fire, but that was a much smaller fire in terms of acres. If we had the wine country fire, hundreds of thousands of acres, we'd be talking about a fire that go from Richmond to Hayward, and that is possible we have more grasslands than those areas, but yeah, I think the Oakland Hills fire showed that it is not inconceivable to have a very, very large fire. If you have many starts, which they had up there, that was the big difference, the Oakland Hills fire we had one start, this wine country fire might have had . . . twenty, and that’s the big difference.”

Dr. Westerling: I think it’s quite similar to the Witch Fire and the Cedar Fire down in San Diego in 2004 and 2007, both of those were in October too.

Emma: We have another question from Deborah Kahn again from E&E, she has a follow up question: “How important is it for homeowners to maintain defensible space given these Napa and Sonoma fires that grew so quickly, there wasn't really anything that anyone could do was there?” Thanks Deborah for the question.

Dr. Westerling: So I think it depends on how the housing is constructed, and not just the building codes, but how it is arranged on the landscape. If you've got a small area around your house that you control, then a lot of the danger can come from the house next door to you burning. But if we can arrange development on a landscape so that it's more clustered and we have broader defensible spaces around it for development, in that wildland urban interface, I think it will be easier for firefighters to protect it, than if we have lots of contact areas where dense vegetation is adjacent to developed areas. But we've seen in other sorts of contexts like in the Yellowstone fires, you know, it's not developed, but there were different parts of the fire season back there in 1988 when the fires were burning fires more intense versus less intense and when the intensity was lower, the condition of the fuel that had burned in preceding years made a big difference in the fire pathway, pattern and severity, whereas later in the season everything was burning, when the conditions were really severe it didn't matter that some areas had burned more recently and others hadn’t. And I suspect it's a similar thing with the Santa Rosa fires in the sense that vegetation clearing makes a difference, but how much of a difference it makes is probably something that depends on how severe the fire conditions are as well.

Dr. Stewart: I think it's important, in addition to defensible space, which is what most of the posters around committees, you know landowners over time, they can end up leaving a lot of hazardous fuels right next to their house—if they store firewood right next to the house where they can get it, if their lawn mower is underneath the deck and it has the gas canister there, there's a lot of other sources if they actually have bushes that could catch on fire, there's a lot of things right around the house that may be more important, especially when embers are flying into the neighborhood, that it isn't vegetation next to you catching fire, it's vegetation half a mile away that is basically showering your house with embers. In that case, a lot of the work is around the house, in keeping those, often detailed issues, like not keeping firewood next to your back door, are equally as important as the defensible space.”

Emma: Great thank you. I'd like to ask a question about long term health impacts and especially if we’re expected to see any mental health impacts following these fires in the communities that have experienced them.

Dr. Rudolph: We should expect to see mental health impacts in people who have suffered through these wildfires. We know from a variety of studies on people following wildfires in Australia and California and other places that the incidences of depression and post traumatic stress disorder go up. It's really important that we provide access to mental health services for people that have experienced the fire, particularly for those that have lost their homes, or been evacuated, or suffered severe property damage, or other injury in the fires. And also we need to make sure that people know to access those services. It's especially important that young children and their mothers seek help if they're having any concerns at all, or if their children are exhibiting any kind of continued anxiety or other symptoms after they've experienced a wildfire.

Emma: Great thank you Linda. Alright and another question from Craig Miller. He writes: “Is there evidence that Diablo and similar winds are increasing, or will increase, because the climate change?”

Dr. Westerling: There was a headline I saw just this last week about the potential for it to be intensified by climate change, but I haven’t had a chance to read the paper yet. But there was something out just recently. I could try and track down the reference for you afterward.

Dr. Stewart: This is a Bill Stewart. There's been quite a bit of research on the Santa Ana fires and you know the meteorological issues here. I know at San Jose State they have a number of experts that work in this area, and they've been working on this. I wouldn't be surprised if they are predicting more fires, because heat is what drives the winds in the first place, so I do think the meteorologists are the people to ask on that question.

Dr. Westerling: There's another aspect to it too, a more climatological aspect, and it's really the intersection between the fuel still being dry into the fall and beginning of the intensification of the wind because the Diablo winds or Santa Anas in the south. And climate change makes our precipitation more variable, and so under some of the future scenarios we see that there are fewer storms in some years and they might start later in the year, so we if you don't get significant precipitation until November or December, you really greatly expand the period when that wind is going, and the fuels are still dry, and the relative humidities are still pretty low. And so, even if the winds didn't change significantly, if our precipitation in the fall becomes more variable, for some years we don't get any quite late in the year, then these winds could have a much bigger impact in the sense of extending a fire season further into the fall and winter.

Emma: Great. Alright, our next question is another one from Alastair Blant. This is a question for Bill. He writes, “Bill, you said warming trends are creating an effect where it seems like we’re living one or two counties south every decade. What does that look like in terms of vegetation? Are plant communities in northern California beginning to thin out and become more desert like? What is happening in Southern California? Will the landscape eventually resemble something more like Mexico’s?”

Dr. Stewart: Yeah, Professor David Ackerley here at U.C. Berkeley has done a lot of research on this, but what we're seeing is not a shift towards more desert like, we're actually just seeing a lot more shrubs, which are outcompeting trees. And the shrubs, ere because often many of the shrubs have much more flammable leaves, that's shifting forest to shrub lands, that's one thing that seems could be increasing the fire risk in some of these landscapes. And I do think Southern California probably is going to have hotter conditions. Shrubs do great in hotter conditions, so the grasses, but trees don't. But the shift towards shrub lands, that's the most flammable vegetation we have in California, so warmer shrub lands does not portend well for us.

Dr. Westerling: The other thing is that while climate is shifting steadily, especially temperatures warming, and over time that might change sort of what the reference vegetation would look like, the vegetation that we have on the ground now, and that we look at as our record to associate what types of vegetation go with what kinds of climate, came about over a relatively stable climate regime that lasted thousands of years. Climate change introduce unprecedented rates of change for anything that we've been able to measure or recreate from from the Holocene. So we're looking at two problems: one is that it’s things like wildfire and drought and beetles that really drive the change that we perceive. Even though climate change is progressing basically all the time, the landscape gets reorganized in steps, or sudden shifts, as we have these big intense disturbances. Not just these increases in wildfire that we've seen around the West, but also the beetle and drought dieback. We lost a huge fraction of our canopy, our forest canopy here in the Sierra Nevada because of the recent drought.

And these changes, when the ecosystem starts to recover after these the disturbances, they're recovering under a new climate regime, compared to what formed before, and so they may not go back and reset to what they looked like before, but also it's really hard for us to predict what's going to happen in sort of the intermediate term, because instead of climate change being a one step thing, and then everything adjusts to where the new climate spaces are on the landscape, instead what we have is accelerating change projected for the rest of this century. If we stabilize our emissions and reduce our emissions to stabilize atmospheric concentrations there are still a lot of climate feedbacks in the global earth system that would keep temperatures increasing and climate changing for a while, as a response to what we we’ve triggered.

And that makes it very hard to predict what this complex system of interactions is going to do in the immediate term. So, we have a lot of fluctuations in vegetation ahead of us. And we're trying really hard to understand how that is going to evolve over time. It’s easier to think about what it would look like 500 years from now than it is to tell you what it’s going to look like 50 years from now.”

Emma: I’m going to ask a question from Climate Signals. The question posed to the whole panel is: “Were the wildfires early this year in Southern California an example of the shifting or extending wildfire season?”

Dr. Stewart: This is Bill Stewart. The biggest change has been having wildfires later and later into the fall. You know we didn't really have any massive wildfires in Southern California this year, compared to some of the ones we’ve had in San Diego and other places a few years ago. We a lot in the Sierra Nevada but I don't remember the really big ones in Southern California compared to some the previous years. But the long term trend has been more and more acres burning in Southern California decade upon decade.

Dr. Westerling: And the fire season is getting earlier and earlier decade by decade too but you have to look at the averages over multiple years. I could point to specific events, you know, more than a decade ago we had a fire in January. So it's not that it couldn't happen before it’s just that it’s more likely now.

Emma: Got it, thank you. I wonder if the panel could speak a little bit about the extent to which higher temperatures have played a role. People have talked about drought, and dried foliage, but if you could also speak about increasing temperatures across the state and what impact that has on the wildfires and also public health that would be great.

Dr. Westerling: Well we did address a little bit right, talking about the increased evaporation intensifying the drought. How much moisture you have in the landscape is partly the input, so how much carried over previous years and how much precipitation you get in the current year. And then there’s the outflow, the runoff and evaporation. Warmer temperatures mean more evaporation. Climate change also mean enhanced variability in the precipitation, so more extreme wet and dry events. The combination of that high background variability that's getting exacerbated by climate change and the warmer temperatures that increase evaporation means that your droughts get enhanced and become more severe and we’re also seeing more drying out over time.

One way to think about it is like it’s a bathtub -- how much moisture is in the bathtub? And you have two dials: one controls how much precipitation is going in and that’s getting more variable and maybe slightly increasing over time on average, and the other is the temperature and that's mostly going in one direction, it’s getting warmer, and that’s increasing the evaporation coming out. And the thing is you would need way more of an increase in precipitation than anything that's being projected or that's being observed for our region to counteract the cumulative drying of year after year warmer temperatures. So, overall, that means our landscape is drying out. And that is driving, ultimately, shifts in vegetation, perhaps more shrubland and less forest. They have a paper out this year, Matt Hertow and a student of his, Shung Yung, looking at how the Sierra Nevada forests may transition from a net sink for carbon to a net source of carbon to the atmosphere as temperatures continue to increase. And we see this kind of dynamic throughout the west, progressing at different rates in different types of vegetation.

Dr. Rudolph: I’ll just jump in here and say that heat is the extreme event that has the most significant health impacts that we're experiencing in California and the U.S. right now, both in terms of mortality and other impacts. And we know that cardiovascular disease deaths increase with extreme heat events in addition to hospitalizations and deaths from acute heat illness and heat stroke. But we also know from studies that have been done by my colleagues at the California Office of Environmental Health Hazard Assessment that higher temperatures are associated with more emergency room visits for heart disease stroke, diabetes and renal failure. So we should be very concerned about what increasing temperatures and greater extreme heat events are doing in terms of the public health impacts.

Emma: Great thank you, that's very helpful. Alright another question from Chris Roberts at Curbed San Francisco and he writes: “Power lines were the cause of the 2015 fire, I may mispronounce the name here, in Butte. There is educated speculation that power lines falling or sparking in the winds may have caused this fire as well. Based on what we know at this point, does this seem to be the most likely cause, or can we not say what the cause was just yet?”

Dr. Stewart: This is Bill Stewart. There definitely were reports of power lines going down and transformers exploding, whether they actually started the fire they are still under investigation. They have a very experienced crews of fire investigators out there, and they'll probably identify the exact trees involved. There was no lightning events going on during that evening, so that seems to be the leading hypothesis now, that numerous trees hit numerous power lines in that area. We had so many starts, it wasn’t just one. There were a lot. It's a very, very painstakingly detailed investigation they do to really get at that this. It has already started, there are people out there working right now. And it's a big money question, is someone libel or what. So everybody's working to get this accurate and right so it stands up to future scrutiny.

Emma: And certainly if a power line is down in a place like New York it doesn't necessarily lead to massive wildfire, so it seems like while that may have sparked it then conditions like wind and heat and dryness exacerbate something to be the crisis that it turned into.

Dr. Stewart: The other big challenge is it seems like much of the wind event and therefore the ignitions started at night, when it's very hard to see anything, because it's all dark except for the fires.

Emma: So I’ll prompt one more time for questions. Okay, here's a follow up question. “Is there a possibility that a falling line started the first fire, because they fell on trees that were killed because of drought conditions?

Dr. Stewart: The bigger cause was was probably the winds knocking down—whether they were lives trees or trees that had their roots rotted out—trees definitely fell down, a lot of trees fell down. Whether they are alive or dead, right now, this time of year, as LeRoy pointed out, they are probably dry, so it really didn’t actually matter if they were alive or dead because the grass is all dry, the litter is all dry. At this time of year,  if sparks hit the ground there was a lot of kindling on the ground in late October in Sonoma County.

Emma: Alright, well we're coming up on 2:29p. I have promised our panelists that we would be finished at 2:30p out of respect for their schedules. I just want to open up to the panelists quickly and see if anyone has any closing thoughts. We've covered a lot of ground here.

Dr. Rudolph: No, we really appreciate that you put this together Emma and Climate Nexus, so thank you.

Emma: Certainly.

Dr. Westerling: I think it's good to keep in mind that this is part of a broader shift going on in our climate system, and it’s going to continue for some time. For the foreseeable future, forest fires are going to continue to increase until fuel becomes more of a limitation. Chaparral can regenerate fuels pretty quickly. So this is really part of what we have to learn to adapt to live with as it intensifies with climate change.

Emma: Thank you Dr. Westerling. So if people are interested in the recording please e-mail me. Again, I’m Emma Stieglitz from Climate Nexus my e-mail addresses E.S.T.I.E.G.L.I.T.Z at climatenexus.org. Happy to send you an audio file of this call. And if there are questions that we didn't get to, or follow up questions, I would be happy to follow up with you after the call and see if we can connect you with some of our panelists for more detailed information. Thank you for everyone who joined, and a huge thanks to our panelists for lending your time and expertise to this subject. We really appreciate it, and that concludes the call.

Have a great rest of your day everybody.

Thank you.