Tag Archives: Forest Fires

Isotopes Point To Natural CO2 Origins

21 Thursday May 2026

Posted by in Climate science, Global Warming

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Evidence is piling up that claims of anthropogenic global warming (AGW) and an incipient climate apocalypse have constituted vast exaggerations if not outright falsehoods. And for several years it’s been hard to miss indications that the social mood has shifted away from climate alarmism. That’s true inside and outside the climate science community, where so-called “consensus” has given way to growing skepticism and dissent.

Backing Away From Crazy Town

The most prominent shift in the climate “vibe” involves the Intergovernmental Panel on Climate Change (IPCC), which has grown to be the chief climate-change propaganda arm of the United Nations and the environmental left. The IPCC has now received new climate change scenarios from an upstream committee to be used in the IPCC’s upcoming Seventh Assessment Report (AR7). Roger Pielke Jr. reviewed the changes, which are noteworthy due to their scaled-back projections of atmospheric CO2 concentrations and global warming.

The three most extreme scenarios for CO2 forcings have been eliminated: RCP8.5, SSP5-8.5, and SSP3-7.0. These scenarios have become “implausible”, according to this paper, which credits renewable energy and climate policy for the changed outlook. “Implausible” is the right word, but this narrative is a preposterous attempt to save face. The extreme scenarios were never realistic, and that should be obvious to even the climate-change orthodoxy.

Given the IPCC’s track record, it might be surprising that the extreme scenarios were so influential. The most extreme, RCP8.5, was used in over 17,000 papers as the basis of climate change and various damage calculations. It’s not been unusual for documents to go so far as to describe RCP8.5 as “Business as Usual”.

The best argument I’ve heard in favor of the extreme scenarios is that they represented stress tests that could be used to interpolate many less extreme scenarios without the substantial cost of additional model simulations. A key quote is that “It’s easier to interpolate than extrapolate.” That’s fine, though my own experience in running model simulations informs me that the comment cited at the link likely exaggerates the cost of model runs. Furthermore, “interpolating” complex models over decades is not a simple business, or non-controversial for that matter. And perhaps most importantly, it would have been incumbent on the IPCC and other climate authorities to make clear to the press, the public, educators, and policymakers that the most extreme scenario did NOT represent BAU, and were not to be interpreted as plausible outcomes. That critical disclaimer simply fell through the cracks.

Models, Reality, and Data

That such extreme scenarios should prove influential as key inputs to other models speaks to the confusion between empirical evidence and a narrative treated as consensus by the left, including much of the press. It’s bad enough that so many observers unknowingly take model outputs as empirics. That is all too common in discussions of climate change, but these extreme model outputs go well beyond that sort of confusion, and their promotion seems quite intentional.

Challenging “Consensus”

In my last post I discussed Jonathan Cohler’s take-down of so-called “global temperature” measurements, particularly the Global Mean Surface Temperature. As Cohler notes, this metric is no more valid as a representation of physical reality than an infinite array of other calculations. Cohler has made several other noteworthy contributions to the growing canon of climate realism.

Here I wish to discuss another important Cohler paper, this one with coauthor Willie Soon, debunking the widely-held belief that rising atmospheric CO2 concentrations are attributable to human activity, and more specifically the burning of fossil fuels. Below, I try my best to explain the logic and empirics underlying the Cohler-Soon (CS) conclusions in nontechnical language. Any mistakes are mine.

Isotopic Signatures

CS take advantage of the isotopic “signature” of net carbon additions to the atmosphere. This refers to the atomic makeup (number of neutrons) of different carbon sources. They find that the isotopic signature of the aggregate source flow has been quite stable for decades, even centuries based on proxy measures. But fossil fuels have a more extreme isotopic signature than natural carbon sources. These signatures are illustrated in the graphic at the top of this post, taken from a paper by Heather Graven, et al. Thus, CS conclude that the burning of fossil fuels has had little impact on the (trendless) aggregate source signature (NOT the cumulative atmospheric signature on the upper left of the graphic, which has risen). The source signature should have trended more decisively if fossil fuels dominated the rise in atmospheric CO2, especially as human emissions grew over the decades.

CS find that atmospheric carbon tends to dissipate fairly rapidly due to natural processes: 3.5 – 4 years, contrary to frequent assertions of very slow decay (see CS Table 1). It’s what plants breathe, converting it to oxygen; oceans absorb a great deal of carbon as well. Furthermore, human emissions have accounted for only about 4% of gross fluxes of CO2 into the atmosphere each year. CS state that the balance comes from natural sources such as “oceanic processes and … terrestrial respiration.” These include plant decay and geothermal activity. These natural sources have less extreme isotopic signatures than fossil fuel emissions. (I say “extreme” because most of these signatures take negative values.) Based on these facts, CS show that increases in natural fluxes can easily account for the added CO2 that has accumulated since the 1950s.

An Alternative Explanation

The meaning of the Cohler-Soon paper is that to-date, all but the last several years of human emissions of CO2 are still present in the atmosphere. Obviously, this concentration would grow if annual emissions grow. But to-date, the stability of the net source signature suggests that some other carbon source is acting to offset the extreme isotopic signature of CO2 from burning fossil fuels. In fact, that logic suggests that ocean outgassing, geothermal fluxes, plant decay and the soil biosphere can account for the added atmospheric carbon. Those natural sources have less extreme isotopic signatures, especially geothermal, followed by ocean outgassing.

But what caused this increase in natural fluxes? CS maintain that warming temperatures since the end of the Little Ice Age (1300 – 1850) led to the increase in atmospheric carbon from oceanic and biospheric fluxes. The higher temperatures themselves were not driven by CO2 concentrations but by greater solar radiation, changes in cloud cover, ocean cycles, and deep ocean heating. This conclusion is supported by earlier research conducted by Soon and other authors cited in the CS paper.

Failed Models and Predictions

More and more, we see that virtually every assertion made by the climate-crisis orthodoxy lacks evidence that stands up to scrutiny. The earth is not “on fire”. It is greening beautifully. Here’s a helpful timeline of failed, catastrophic climate predictions made since the mid-1960s. There will be many more. One such failed prediction calls for severe storms to increase in frequency and intensity, but that trend is negative. The trend in forest fires is negative as well, as are droughts, despite alarmist predictions. The oft-cited trend in sea levels has been in place since the Little Ice Age, with no recent acceleration. See this page for information on other climate phenomena that run contrary to the alarmist narrative.

Summary

Evidence from isotopic measures of CO2 over recent decades, and proxy measures over several centuries, show that the much-dreaded rise in carbon concentrations had its probable origin in natural sources. Human emissions are too inconsequential relative to natural sources, and carbon dissipates too rapidly in the atmosphere to support the hypothesis of rising carbon concentration based on human activity. Natural sources include geologic and oceanic outgassing, along with decaying matter and soil. These fluxes were stimulated by warmer temperatures brought on by stronger solar radiance, geothermal deep ocean heating, and changes in cloud cover.

So the evidence strongly indicates that higher temperatures induced more atmospheric carbon fluxes, not vice-versa. But how can that be when the models used by the climate science establishment embed assumptions to the contrary? The answer is that they are models based on sketchy empirics, not reality, and the line of causation seemed logical to modelers searching for a culprit. Furthermore, the causal chain upon which the models depend was often politically and financially expedient. While higher carbon concentrations can lead to rising temperatures given radiative forcing, the effect is weak and tapers at higher CO2 concentrations.

The IPCC’s retirement of its extreme climate scenarios represents a significant change. It is not that the extreme model scenarios have “become less likely”. It’s because those scenarios were always farfetched and reality finally caught up with the extremist narrative. This should give us all pause whenever policymakers attempt to sell costly initiatives to address climate change, anthropogenic global warming, climate sustainability, or the alarmist euphemism of the day. We’re not yet free of the exaggerated climate narratives, as this piece regarding the new IPCC scenarios tells us.

The Disastrous Boomerang Effect of Fire Suppression

15 Thursday Nov 2018

Posted by in Environment, Wildfires

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We can lament the tragic forest fires burning in California, but a discussion of contributing hazards and causes is urgent if we are to minimize future conflagrations. The Left points the finger at climate change. Donald Trump, along with many forestry experts, point at forest mismanagement. Whether you believe in climate change or not, Trump is correct on this point. However, he blames the state of California when in fact a good deal of the responsibility falls on the federal government. And as usual, Trump has inflamed passions with unnecessarily aggressive rhetoric and threats:

“There is no reason for these massive, deadly and costly forest fires in California except that forest management is so poor. Billions of dollars are given each year, with so many lives lost, all because of gross mismanagement of the forests. Remedy now or no more Fed payments.”

Trump was condemned for his tone, of course, but also for the mere temerity to discuss the relationship between policy and fire hazards at such a tragic moment. Apparently, it’s a fine time to allege causes that conform to the accepted wisdom of the environmental Left, but misguided forest management strategy is off-limits.

The image at the top of this post is from the cover of a book by wildlife biologist George E. Gruell, published in 2001. The author includes hundreds of historical photos of forests in the Sierra Nevada range from as early as 1849. He pairs them with photos of the same views in the late 20th century, such as the photo inset on the cover shown above. The remarkable thing is that the old forests were quite thin by comparison. The following quote is from a review of the book on Amazon:

“Even the famed floor of Yosemite is now mostly forested with conifers. I myself love conifers but George makes an interesting point that these forests are “man made” and in many ways are unhealthy from the standpoint that they lead to canopy firestorms that normally don’t exsist when fires are allowed to naturally burn themselves out. Fire ecology is important and our fear of forest fires has led to an ever worsening situation in the Sierra Nevada.”

I posted this piece on forest fires and climate change three months ago. There is ample reason to attribute the recent magnitude of wildfires to conditions influenced by forest management policy. The contribution of a relatively modest change in average temperatures over the past several decades (but primarily during the 1990s) is rather doubtful. And the evidence that warming-induced drought is the real problem is weakened considerably by the fact that the 20th century was wetter than normal in California. In other words, recent dry conditions represent something of a return to normal, making today’s policy-induced overgrowth untenable.

Wildfires are a natural phenomenon and have occurred historically from various causes such as lightning strikes and even spontaneous combustion of dry biomass. They are also caused by human activity, both accidental and intentional. In centuries past, Native Americans used so-called controlled or prescribed burns to preserve and restore grazing areas used by game. In the late 19th and early 20th centuries, fire suppression became official U.S. policy, leading to an unhealthy accumulation of overgrowth and debris in American forests over several decades. This trend, combined with a hot, dry spell in the 1930s, led to sprawling wildfires. However, Warren Meyer says the data on burnt acreage during that era was exaggerated because the U.S. Forest Service insisted on counting acres burned by prescribed burns in states that did not follow its guidance against the practice.

The total acreage burned by wildfires in the U.S. was minimal from the late 1950s to the end of the century, when a modest uptrend began. In California, while the number of fires continued to decline over the past 30 years, the trend in burnt acreage has been slightly positive. Certainly this year’s mega-fires will reinforce that trend. So the state is experiencing fewer but larger fires.

The prior success in containing fires was due in part to active logging and other good forest management policies, including prescribed burns. However, the timber harvest declined through most of this period under federal fire suppression policies, California state policies that increased harvesting fees, and pressure from environmentalists. The last link shows that the annual “fuel removed” from forests in the state has declined by 80% since the 1950s. But attitudes could be changing, as both the state government and environmentalists (WSJ, link could be gated) are beginning to praise biomass harvesting as a way to reduce wildfire risk. Well, yes!

The reason wildfire control ever became a priority is the presence of people in forest lands, and human infrastructure as well. Otherwise, the fires would burn as they always have. Needless to say, homes or communities surrounded by overgrown forests are at great risk. In fact, it’s been reported that the massive Camp Fire in Northern California was caused by a PG&E power line. If so, it’s possible that the existing right-of-way was not properly maintained by PG&E, but it may also be that rights-of-way are of insufficient width to prevent electrical sparks from blowing into adjacent forests, and that’s an especially dangerous situation if those forests are overgrown.

Apparently Donald Trump is under the impression that state policies are largely responsible for overgrown and debris-choked forests. In fact, both federal and state environmental regulations have played a major role in discouraging timber harvesting and prescribed burns. After all, the federal government owns about 57% of the forested land in California. Much of the rest is owned privately or is tribal land. Trump’s threat to withhold federal dollars was his way of attempting to influence state policy, but the vast bulk of federal funds devoted to forest management is dedicated to national forests. A relatively small share subsidizes state and community efforts. Disaster-related funding is and should be a separate matter, but Trump made the unfortunate suggestion that those funds are at issue. Nevertheless, he was correct to identify the tremendous fire hazard posed by overgrown forests and excessive debris on the forest floor. Changes to both federal and state policy must address these conditions.

For additional reading, I found this article to give a balanced treatment of the issues.

Forest Fires Ignite Climate Change Delusions

10 Friday Aug 2018

Posted by in Global Warming, Wildfires

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The geographic extent of this summer’s forest fires won’t come close to the aggregate record for the U.S. Far from it. Yes, there are some terrible fires now burning in California, Oregon, and elsewhere, and the total burnt area this summer in the U.S. is likely to exceed the 2017 total. But as the chart above shows, the burnt area in 2017 was less than 20% of the record set way back in 1930. The same is true of the global burnt area, which has declined over many decades. In fact, this 2006 paper reported the following:

“Analysis of charcoal records in sediments [31] and isotope-ratio records in ice cores [32] suggest that global biomass burning during the past century has been lower than at any time in the past 2000 years. Although the magnitude of the actual differences between pre-industrial and current biomass burning rates may not be as pronounced as suggested by those studies [33], modelling approaches agree with a general decrease of global fire activity at least in past centuries [34]. In spite of this, fire is often quoted as an increasing issue around the globe [11,26–29].”

People have a tendency to exaggerate the significance of current events. Perhaps the youthful can be forgiven for thinking hot summers are a new phenomenon. Incredibly, more “seasoned” folks are often subject to the same fallacies. The fires in California have so impressed climate alarmists that many of them truly believe global warming is the cause of forest fires in recent years, including the confused bureaucrats at Cal Fire, the state’s firefighting agency. Of course, the fires have given fresh fuel to self-interested climate activists and pressure groups, an opportunity for greater exaggeration of an ongoing scare story.

This year, however, and not for the first time, a high-pressure system has been parked over the West, bringing southern winds up the coast along with warmer waters from the south, keeping things warm and dry inland. It’s just weather, though a few arsonists and careless individuals always seem to contribute to the conflagrations. Beyond all that, the impact of a warmer climate on the tendency for biomass to burn is considered ambiguous for realistic climate scenarios.

And what of the “mega-fires” burning in the West, like the huge Mendocino Complex Fire and last year’s Thomas Fire? Unfortunately, many decades of fire suppression measures — prohibitions on logging, grazing, and controlled burns — have left the forests with too much dead wood and debris, especially on public lands. From the last link:

“Oregon, like much of the western U.S., was ravaged by massive wildfires in the 1930s during the Dust Bowl drought. Megafires were largely contained due to logging and policies to actively manage forests, but there’s been an increasing trend since the 1980s of larger fires.

Active management of the forests and logging kept fires at bay for decades, but that largely ended in the 1980s over concerns too many old growth trees and the northern spotted owl. Lawsuits from environmental groups hamstrung logging and government planners cut back on thinning trees and road maintenance.

[Bob] Zybach [a forester] said Native Americans used controlled burns to manage the landscape in Oregon, Washington and northern California for thousands of years. Tribes would burn up to 1 million acres a year on the west coast to prime the land for hunting and grazing, Zybach’s research has shown.

‘The Indians had lots of big fires, but they were controlled,’ Zybach said. ‘It’s the lack of Indian burning, the lack of grazing’ and other active management techniques that caused fires to become more destructive in the 19th and early 20th centuries before logging operations and forest management techniques got fires under control in the mid-20th Century.”

The annual burnt area from wildfires has declined over the past ninety years both in the U.S. and globally. Even this year’s wildfires are unlikely to come close to the average burn extent of the 1930s. The large wildfires this year are due to a combination of decades of poor forest management along with a weather pattern that has trapped warm, dry air over the West. The contention that global warming has played a causal role in the pattern is balderdash, but apparently that explanation seems plausible to the uninformed, and it is typical of the propaganda put forward by climate change interests.