How do you explain the graph in skye6’s previous post?
Mike
The PNAS paper uses “Burned Area” as a measure of wildfires and “maximum near surface temperature” as an indicator of heating from climate.
This figure from the paper shows the strong correspondence between burned acres and surface temperature, which is rising over time due to climate change.
The correlation for the early period 1971-1995 was not statistically different than that from 1996-2021. If the 5X increase in burned acres was due to there being much denser forests (or some other non-climate factor) in 1996-2021, then the correlation between burned acres and surface temp should have changed with time. It did not. This supports surface temp as being the prime determinant of wildfire frequency
Or as the PNAS paper states:
" Our results suggest that changes in human environmental factors, including changes in biomass and fire management practices during the period of record, did not significantly affect the stability of the climate-fire relationship at the scales analyzed here. For instance, we assess the solidity of fire‐climate relationships during 1971 to 2021 by comparing regression statistics based on only data from 1971 to 1995 versus 1996 to 2021 (SI Appendix, Fig. S2). Similar statistical relationships for both periods strongly suggest that nonclimate factors did not cause a change in the fire–climate relationship during the study period."
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That graph is Oregon, not California.
Climate change is probably causing an increase in fire weather, periods of hot, dry, windy weather. If we make no changes, this leads to more fires. Human behavior can amplify this by building in fire-prone areas, or adapt through wildfire prevention strategies. This is just like floods. Climate change causes sea level rise - whether the sea level rise leads to floods and economic damage depends on how we adapt.
The IPCC says
Fire weather conditions (compound hot, dry and windy events) have become more probable in some regions (medium confidence ) and there is high confidence that they will become more frequent in some regions at higher levels of global warming.
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Do you think that Oregon forest fire fighting is that much different than CA? Or that climate change is different between the states?
Mike
How much desert is in Oregon? Riddle me this!
In case your google isn’t working today…it is ~25%
Mike
Not the same thing. The designation of desert is sand for soil. That is different in Palm Springs than anywhere in Oregon.
Not so. The determining factor is aridity. While sand is often a feature, deserts can also have vast areas of rocks and gravel peppered with occasional plants. Antarctica is also considered to be a desert.
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The elevation is higher and colder in the far northern part of Ca and Oregon. As far as danger, Ca fires are more dangerous … much more area to burn and much hotter wildfires. Even in summer months Oregon is much cooler than California
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Fair enough but I have heard the US described as 40% desert because of sandy soil content.
What Red Cloud said. Much of Oregon east of the Cascades, like much of all the Great Basin area, is sandless desert.
Where I live, only the usually dry river bottom has sand. But the arid Bajio of my home extends uninterrupted from the low mountain ridge of the San Miguel Pachecos just 20 kilometers south of my house in central Mexico, all the way north 2600 or so kms to Las Vegas and beyond, with red fox, roadrunners, and Joshua Trees or their cousin the Yucca palmiferia all the way. Not much sand.
d fb
Yep I looked up that prior claim I had heard of 40% sand. It is only 8%.
I wonder where the source was for that TV broadcast years ago.
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I’d have to see a citation for that because it is wrong. As mentioned, it is really defined as arid land with less than a foot of rainfall annually (or something like that). Sand has nothing to do with it. Stop beating the dead horse.
JimA
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The key here is “leads to.” This study estimated the number of wildfires in western forests over the last three thousand years using carbon samples. It found that western forest fires peaked in the late 1800s.
This finding is supported by contemporaneous accounts of white settlers who reported needing to use lamps during the day time due to darkness from wildfire smoke. Mark Twain visited Puget Sound on a speaking tour in the late 1800s and was unable to see the mountains or forests because they were obscured by smoke. A single fire in Washington State in 1910 burned over three million acres. By comparison, the Camp Fire burned about 150,000.
From the abstract:
Since the late 1800s, human activities and the ecological effects of recent high fire activity caused a large, abrupt decline in burning similar to the LIA fire decline. Consequently, there is now a forest “fire deficit” in the western United States attributable to the combined effects of human activities, ecological, and climate changes. Large fires in the late 20th and 21st century fires have begun to address the fire deficit, but it is continuing to grow.
The authors are very clear, climate does play a role in wildfires, but we’re actually experiencing fewer wildfires than can be explained by climate alone. The perceived increase is still below the baseline. The authors also point out that the effects of climate on wildfires occur over long time frames.
I can’t figure out where you are going with this. Have you ever been to eastern Oregon? Looks like a desert to me.
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The key concept here in studying fire in the 20th and 21st century is the policy of fire suppression. The U.S. became quite good at this by mid-century; that’s what accounts for much of the “deficit.” Meanwhile, the fuels have built up, so when fires do break out, there’s much more to burn. While the U.S. has started to use prescribed burns very selectively to remove the buildup of fuels, it is inherently hazardous work and can become uncontrolled if the conditions change. Meanwhile, the fuels continue to accumulate, and the climate is shifting. This is occurring on a vast scale, well beyond our ability to manage it.
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I saw some crap stats on desert area in the US about twenty years ago. It was garbage.