Saturday, December 16, 2017

This should convince the climate skeptics. But it probably won't.

One of the factoids that climate-change denialists cling to is the fact (and it is a fact) that major storms haven't gotten measurably worse.  The damage from storms has gotten measurably worse, but that can be attributed to increased development on coastlines.  It might be that the storms themselves have gotten worse, but the data is not good enough to disentangle the two effects.

But storms are not the only natural disasters exacerbated by climate change.  As I write this, the Thomas Fire has grown to be the third largest in California history.  It only needs to grow another 10% to get to the #1 spot, and since it is only 40% contained at the moment and a new round of Santa Ana winds are blowing even as I write this, it will almost certainly achieve that dubious distinction.

But you can't draw conclusions about long-term trends from any single data point, so why am I bringing this up?  Because the Thomas fire is not an isolated incident.  It is only the latest in a long string of record-breaking fires in California.  If you look at the list of the twenty largest fires in California history, fifteen of them have happened in the last 20 years.  Nineteen of them have happened in the last 50 years.  The only fire on the top 20 list before 1970 was in 1932.

This increase in fire size cannot be the result of human development.  If anything, human development should result in smaller fires, because development removes wildland fuel.

There is also the national climate assessment, which has additional evidence that human-induced climate change is producing more catastrophic weather events.  This report was published by the Trump administration.  If that doesn't convince you that the problem is real and serious, then you will find kindred spirits among the birthers, the lunar landing denialists and the flat-earthers.  Good luck to you.


Luke said...

Do you know how many fires were probably caused by humans? It might be that more recently, less responsible humans more commonly travel into at-risk parts of the wilderness. I'm not sure this could explain everything, but it seems like a possible factor.

Ron said...

> Do you know how many fires were probably caused by humans?

No, but there's data on the total number of fires for the last 15 years:

I haven't done the math, but it sure doesn't look to me like there's any kind of upward trend there.

Also, there are plausible hypotheses about why more humans should make large fires less likely. We have more capacity for fighting fires now than we used to. And yet the fires keep getting bigger (because the droughts keep getting longer).

Publius said...

Wildland Fires: 1 - Studies

>But you can't draw conclusions about long-term trends from any single data point, so why am I bringing this up? Because the Thomas fire is not an isolated incident. It is only the latest in a long string of record-breaking fires in California.

A lot of phenomena are correlated with time, as time is always increasing. If the phenomena is either constantly increasing or decreasing, it will correlate with time. It is easy to find spurious correlations with "time" as the other factor.

What has the peer-reviewed reserach discovered regarding the trend in wildfires 1) due to global warming, and 2) in the Western U.S. specifically:

Global trends in wildfire and its impacts: perceptions versus realities in a changing world, Doer and Santin; Philosophical Transactions of the Royal Society B, May 2016.
".. . . Yet many consider wildfire as an accelerating problem, with widely held perceptions both in the media and scientific papers of increasing fire occurrence, severity and resulting losses. However, important exceptions aside, the quantitative evidence available does not support these perceived overall trends. Instead, global area burned appears to have overall declined over past decades, and there is increasing evidence that there is less fire in the global landscape today than centuries ago. Regarding fire severity, limited data are available. For the western USA, they indicate little change overall, and also that area burned at high severity has overall declined compared to pre-European settlement. Direct fatalities from fire and economic losses also show no clear trends over the past three decades.. . . The data evaluation presented here aims to contribute to this by reducing misconceptions and facilitating a more informed understanding of the realities of global fire."

Long-term perspective on wildfires in the western USA, Marlon et. al.; PNAS, Feb. 2012.
".. . . There has been a slight decline in burning over the past 3,000 y, with the lowest levels attained during the 20th century and during the Little Ice Age (LIA, ca. 1400–1700 CE). Prominent peaks in forest fires occurred during the Medieval Climate Anomaly (ca. 950–1250 CE) and during the 1800s. Analysis of climate reconstructions beginning from 500 CE and population data show that temperature and drought predict changes in biomass burning up to the late 1800s CE. 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."

Publius said...

Wildland Fires 2: - Studies

Is fire severity increasing in the Sierra Nevada, California, USA?, Hanson, Odion; J. International Association of Wildland Fire, Sept. 2013.
".. . . We analysed all available fire severity data, 1984–2010, over the whole ecoregion and found no trend in proportion, area or patch size of high-severity fire. The rate of high-severity fire has been lower since 1984 than the estimated historical rate. Responses of fire behaviour to climate change and fire suppression may be more complex than assumed. A better understanding of spatiotemporal patterns in fire regimes is needed to predict future fire regimes and their biological effects. Mechanisms underlying the lack of an expected climate- and time since fire-related trend in high-severity fire need to be identified to help calibrate projections of future fire. The effects of climate change on high-severity fire extent may remain small compared with fire suppression. Management could shift from a focus on reducing extent or severity of fire in wildlands to protecting human communities from fire."

Are High-Severity Fires Burning at Much Higher Rates Recently than Historically in Dry-Forest Landscapes of the Western USA?, Baker; PLOS One, Sept. 2015.
"Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing.. . . This analysis showed the rate of recent high-severity fire in dry forests is within the range of historical rates, or is too low, overall across dry forests and individually in 42 of 43 analysis regions. Significant upward trends were lacking overall from 1984–2012 for area burned and fraction burned at high severity. Upward trends in area burned at high severity were found in only 4 of 43 analysis regions. Projections for A.D. 2046–2065 showed high-severity fire would generally be still operating at, or have been restored to historical rates, although high projections suggest high-severity fire rotations that are too short could ensue in 6 of 43 regions. Programs to generally reduce fire severity in dry forests are not supported and have significant adverse ecological impacts, including reducing habitat for native species dependent on early-successional burned patches and decreasing landscape heterogeneity that confers resilience to climatic change. Some adverse ecological effects of high-severity fires are concerns. Managers and communities can improve our ability to live with high-severity fire in dry forests."

Publius said...

Wildland Fire 3: Studies

Modern departures in fire severity and area vary by forest type, Sierra Nevada and southern Cascades, California, USA, Mallek, Safford, Viers, Miller; Ecoosphere, Dec. 2013.
".. . . We found that modern rates of burning are far below presettlement levels for all forest types. However, there were major differences between low to middle elevation forests and high elevation forests regarding the components of this departure. Low and middle elevation forests are currently burning at much higher severities than during the presettlement period, and the departure in fire area is overwhelmingly expressed in the low to moderate severity categories; in these forest types, mean annual area of high severity fire is not notably different between the modern and presettlement periods. In higher elevation forests on the other hand, the modern departure in fire area is expressed equally across fire severity categories. Our results underline the critical need for forest and fire restoration in the study area, especially in low and middle elevation forests adapted to frequent, low severity fire. Expanded management of naturally ignited fires for resource benefit is clearly needed, but in many parts of our study area, strategic reduction of forest fuels will likely be necessary before large-scale restoration of fire becomes ecologically, politically, and financially feasible."

Publius said...

Wildland Fire 3: It's Your Government

>This increase in fire size cannot be the result of human development. If anything, human development should result in smaller fires, because development removes wildland fuel.

Governor Brown agrees with your assigning global warming as the cause.

However, what do the researchers point to as the cause of wildfires?

Doer, Santin:
". . . in the USA, only 0.4% of wildfires, whether ignited by lightning or humans, are allowed to burn [11]. All others are actively suppressed. Regarding social perceptions, it is important to stress that, in many of these regions, intentional burning had been used for a very long period both by native people and settlers. Thus, in rural areas fire was understood as part of the landscape management culture [12]. However, the current general public perception is predominantly different. Until very recently, governments refused to present fire as a potential positive ecological factor out of concern that any admission of a positive role for fire would sound contradictory [9]. Smokey Bear in the USA is the best, but not the only, example of effective public awareness campaigns supporting 100% fire suppression . . ."

"The evidence presented here shows that efforts to generally lower fire severity in dry forests for ecological restoration are not supported. Reducing fire severity in dry forests is a goal of the 2003 Healthy Forests Restoration Act (HFRA), the Collaborative Forest Landscape Restoration Program (CFLRP) of the 2009 Omnibus Public Land Management Act, and other government policies and programs. These laws, policies, and programs were developed before sufficient quantitative analysis of rates of recent high-severity fire was available, and with very limited information about rates of historical high-severity fire. Historical evidence, now available from multiple sources across large land areas (Table 1), combined with comprehensive recent fire-severity data, together show that high-severity fire is generally operating at or below historical rates. Thus, reducing fire-severity is fire suppression rather than restoration, as was commonly thought before these new data and analysis were available. Fire suppression is incompatible with laws and programs that mandate or encourage restoration of historical fire regimes and forest structure (e.g., Collaborative Forest Landscape Restoration Program)."

Hmm . . . why would Governor Brown blame the climate for forest fires? Could it be because he wants to direct blame away from government?

The other phenomena that is correlated in time is fire suppression of all forest fires. That is a more important factor than global warming.

Ron said...


Also, roads act as fire breaks:

So more roads should result in smaller fires.


Once upon a time I decided to engage in a debate with a lunar landing denialist. At one point I drew their attention to photos of the Apollo landing sites taken by the Lunar Reconnaissance Orbiter spacecraft:

They said it was photoshopped. I can't prove otherwise. A finite amount of data will always be consistent with an infinite number of conspiracy theories.

Ron said...


Another argument against the more-people-start-more-fires theory: there used to be a "fire season" in California that started around June and ended around September. None of the record setting fires started later than September until the Witch fire in 2007, which started in October. The Thomas fire started in December.

Luke said...


Your points are fair, but they just don't cover all the variables—such as whether the rate of controlled burns has decreased and whether we've suppressed more fires (preventing small-scale burns, thereby building more tinder for large-scale burns). I'm disappointed you have not addressed the peer-reviewed articles @Publius mentioned; PNAS and PLOS One are not terrible journals as far as I know. How can you dismiss them without investigation and claim to value EE&R?