During the last few weeks, a series of wildfires have occurred over the region.
Today's satellite imagery shows where the fires were burning (orange dots), with smoke plumes quite evident. Most of these fires began in grass/range vegetation.
In mid-June, there were a few grass/range fires in the Columbia Basin (see image below).
There has been drumbeat in the media that the wildfires were the result of, or significantly enhanced by, global warming/climate change due to increasing greenhouse gases such as CO2.
For example, a story from the Seattle Times Climate Lab was full of demonstrably false claims (such as claims that wildfires are occurring ahead of schedule due to global warming).
In this blog, I will provide the facts and demonstrate that the global warming connection with the current fires contradicts current scientific understanding.
Fire Ignition
The fires during the first half of summer were either human-initiated or caused by lightning.
Human ignition obviously is not related to increasing greenhouse gases, and neither is lightning.
In fact, I examined this issue with colleagues at the Washington State Climatologist Office, examining the potential for lightning using state-of-the-science regional climate models.
The results were clear: under global warming, there are no increases in lightning activity for Washington State (see sample graphic below for Ross Lake in the WA Cascades)
In short, we can say definitively that fire initiation in our region has nothing to do with global warming.
The Fuels
Then there are the claims that a lack of snowpack or prematurely dried fuels were important in the fires this summer, with both due to global warming. This is demonstrably false.
A map of the fires this year (below) shows that nearly all occurred over grass/rangeland or started in grass/rangeland and then spread into terrain.
Because the fires started at lower elevations, the below-normal snowpack of the last year had no impact on these fires.
Even at one higher-elevation fire (Little Giant), the fire started in an open area of a previous burn with lots of grass and downed trees.
A key point is that the range/grass areas were already dry, as would be expected this time of the year, even without any global warming.
Their moisture content was NEAR NORMAL before the fires.
Want proof? The US Forest Service summarizes the fuel moisture for various regions of the Northwest (see below)
Consider region 10, which includes many of the fires. The 100-hour fuel moisture (small vegetation) has been near normal (the gray shaded area), so was the ERC (energy release component) of the fuels.
In summary, any claims that human-caused global warming contributed to the recent Northwest wildfires are demonstrably false.
Lightning ignited fuels of normal dryness.
But there is something that has radically increased the chances of wildfires east of the Cascade crest: the invasion of highly flammable invasive grasses, such as cheatgrass. A map of the "exotic" grasses is shown below. You won't hear about this in certain media and by some advocacy groups. But the increase of these grasses during the past half-century has greatly enhanced the flammability of the landscape.
Yes but you say the lower level fuels are dry and not related to low snowpack. Are the upper level fuels drier due to lower snowpack? If ignition starts in the lower and spreads to the upper, and those fuels are fdrier... Is that different than usual?
ReplyDeleteSaw this article in Seattle Times and was hoping you would address the mis-information. Great public service Cliff!
ReplyDeleteGiven we are at hottest, driest period of the summer what is the probability of an extended period of hot, dry fire weather in Western Washington?
What about the fires in Canada and Europe? The press and governments (e.g. Canada) are invoking climate change as a major factor in the current fires in those areas. What do you think?
ReplyDeleteand Australia as well
DeleteIf the times is belly aching climate change. Follow the money / source of manipulation campaign.
ReplyDeleteCliff, perhaps you can remind people and me (a google search dependant) about summer of 2014. According to google the snowpack that last winter was slightly above normal. People like to say things dried out earlier this year making an early, therefore long fire season. Well The Carlton complex started July, 14th 2014. Over a decade later, to me that remembers, things arent dryer or hotter or worse than back then. I fought that fire, it was the most intense fire i ever fought. Conditions are ripe for it again here as always are, but with all the fires we have going right now the indgrediants arent mixing like they did for that fire , The Okanogan Complex, or the cold springs so far. Point is, one of the worst fires happened mid July. Things arent earlier than normal nor so far worse. It could be worse. Still not good, but could be worse.
ReplyDeleteYou imply that it is the increase in cheat grass in Eastern Washington that is the reason for the increase in number and size of wild fires in recent years, and not the fact that our summer seasons have become longer, hotter and drier this century. Cheat grass has been present in Eastern Washington and elsewhere in the West for many years but the grasses were especially lush this year due to the mild wet winter and early spring rains. I think it is more likely that prolonged heat and dryness is the main factor in the increase in fires, not only in Eastern Washington, but throughout the world, as is very evident this year. Frequency of ignition, say due to lightning, may not be increasing, but it is not the frequency of lightning that is the main fire-start factor but the nature of the lightning and the condition of the fuels when it occurs. One dry lightning storm can cause many fires which can quickly grow large when fuels are dry and the weather is hot, dry and windy. This was very evident this year in the fires in Eastern Washington and Oregon. Fires such as the Little Giant and those in the Colville and in Eastern Oregon would not have experienced their explosive growth and spread had it not been for the fact that the fuels had become very dry due to the prolonged warm, dry spell in June and July.. Our summers in Eastern Washington have become more frequently warm and dry this century so this may be a sign that global warming is a factor in the recent increase in fires. .
ReplyDeleteCheatgrass is only one of the contributors. The length of the summer season is not relevant. Fuel moisture was near normal...the numbers are clear.
DeleteCan you briefly elaborate on why length of summer is irrelevant? Intuitively, it seems like it would be
DeleteThe length of summer is not changing.
DeleteThe official start and end of summer may not be changing but there is observational evidence that the time between the last frost of spring and the first frost of winter has increased by about 35 days over the last 100 years so warmer temperatures are occurring earlier and later in the season.
DeleteCliff - that FEMS data is pretty extrapolated over variable terrain, no? Is it possible that fuel moisture will vary, especially according to aspect, enough so that solar aspects are drying out earlier than previously? Sounds like a data distribution problem to me.
DeleteI relate this to avalanche hazard across a given zone, say West Slopes South. The hazard is generally applied across the zone, but actual slope and drainage hazard varies considerably.
404--- the same trends are found at other nearby sites, so it is robust
DeleteThank you for putting a spotlight on the science behind this year's fire season and what's really driving it. I wonder how those invasive grasses first arrived in the Northwest and what can be done to eradicate them.
ReplyDeleteMostly in contaminated seed shipments from Europe in the 1800s, I believe.
DeleteThanks for the reply! It goes to show how important it is to keep seeds and other products as free from contamination as possible.
DeleteHere is quick note from the US Forest Service concerning the fires in Oregon. "A new Pacific Northwest Fuels and Fire Behavior Advisory has been issued that helps explain why Oregon's fires have been burning so aggressively this summer.
ReplyDeleteThe advisory, produced by the U.S. Forest Service, says the winter's low snowpack combined with recent drought "has led to live and dead fuels curing significantly earlier than usual," the report said. "Fire activity is already reflecting patterns normally seen much later in the fire season. Alignment in the fire environment is producing extreme fire behavior."
What do you think Cliff???
They clearly made some serious errors. Snowpack is not relevant for most of the fires. Fuel moisture was normal. I showed some of the numbers in my blog--there are more.
DeleteSnyder et al. (2019), “Effects of a Changing Climate on the Hydrological Cycle in Cold Desert Ecosystems of the Great Basin and Columbia Plateau” write that temperatures are warming, evaporation is increasing, snowpack is decreasing, etc. These are all conditions that favor annual invasive grasses over perennial native grasses and shrubs in the shrub steppe and dry forests. Restoration of annual grass dominated areas is becoming more challenging due to these conditions. Fire = more cheatgrass. More cheatgrass = more intense fire. And the invasives are moving higher in elevation and further into north facing aspects. I would hypothesize that we will see more challenging fire conditions as time goes on, invasive grasses expand, temperatures warm, and snowpack decreases in the Columbia basin and dry forests of much of the eastern slope of the cascades. Human caused climate change being a major factor in the changing conditions.
ReplyDeleteI read that paper. It does NOT say say that the current distribution of invasive grasses is connected with global warming. If fact, much of the transition occurred BEFORE global warming was significant.
DeleteI have a questions about "warming" not being a factor for increased lightning strikes. Doesn't warmer hold more water vapor, giving storms extra energy? Doesn't warmer air cause stronger updrafts that push ice and water particles up faster to build up electrical charges? Are studies cited by "climate experts" showing for every 1°C (1.8°F) of global warming, lightning strikes could increase by about 12% credible-accurate?
ReplyDeleteThank You
data shows NO increase in lightning over the NW. Lighning generation is much more complex than you are suggesting
Delete