Have we tipped? Are we in a positive feedback loop?


Wildfires Are Set to Double Canada’s Climate Emissions This Year
Early estimates of the carbon released by the fires far surpass the country’s total emissions in 2021. And fire season isn’t over yet.

When the greenhouse gases released from Canada’s 2023 wildfires are eventually tallied, they will be at least double the emissions from all other sectors of the nation’s economy combined, according to a top government scientist who has spent three decades measuring the carbon footprint of forests.

The 2023 emissions are “off the scale” compared to previous years, said Werner Kurz, a senior research scientist with Natural Resources Canada. Kurz’s team helped create a carbon budget model for Canada’s forestry sector which is used by governments and scientists around the world.


Have we tipped? Not likely. As linked in another thread, 24 years of satellite data show a decreasing trend in savannah and grassland burn area and no trend in forest fires.



It’s unlikely that Canada will have the same kind of severe fire season next year. It will take a decade or two for the burned out areas to regrow the forest to where it’s combustible again.

Of course, that doesn’t mean other areas won’t burn.


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Good news on the wildfire emissions front – the trend is declining.



Depends on how the data is analyzed. This is not a trivial task, which led one research group to note in 2022:

No high-resolution global satellite-based assessment of forest loss due to fire employing consistent definitions and methods across biomes has been available to date. https://www.frontiersin.org/articles/10.3389/frsen.2022.825190/full

This group attempted such a study using more refined methodology and they found:

We find an increasing global trend in forest loss due to fire from 2001 to 2019, driven by near-uniform increases across the tropics, subtropical, and temperate Australia, and boreal Eurasia. This is part of their results:


Another study modeled “fire weather”, the weather conditions optimal for wildfires. Their modeling indicates what we are only just entering the period when the risk of wildfires due to global warming is projected to accelerate. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020RG000726



From Yang et al. (2014) a reconstruction showing the decreasing trend going back over a century.


Burned area and Forest loss are different measures, and so could move in different directions. CAMS data says there is less burned area in the African savanna, and lower CO2 emission globally from wildfires. But savanna has few trees. As the climate warms, the risk of wildfires is moving further north. Emissions from boreal forest fires is increasing.

Forest health is important, but wildfires are not listed by wikipedia as a proposed tipping point:

Proposed Global climate tipping element
Greenland Ice Sheet (collapse)
West Antarctic Ice Sheet (collapse)
Labrador-Irminger Seas/SPG Convection (collapse)
East Antarctic Subglacial Basins (collapse)
Amazon Rainforest (dieback)
Boreal Permafrost (collapse)
Atlantic Meridional Overturning Circulation (collapse)
Arctic Winter Sea Ice (collapse)
East Antarctic Ice Sheet (collapse)

Proposed Regional climate tipping element
Low-latitude Coral Reefs (dieoff)
Boreal Permafrost (abrupt thaw)
Barents Sea Ice (abrupt loss)
Mountain Glaciers (loss)
Sahel and W.African Monsoon (greening)
Boreal Forest (southern dieoff)
Boreal Forest (northern expansion)

==== links ====
Record-high CO2 emissions from boreal fires in 2021
“Carbon dioxide emissions from boreal forest fires have been increasing since at least the year 2000, reaching a new high in 2021, Zheng et al. report. Although boreal fires typically produce about 10% of global carbon dioxide emissions from wildfires, in 2021 they produced nearly one quarter of the total. This abnormally high total resulted from the concurrence of water deficits in North America and Eurasia, which was an unusual situation. The increasing number of extreme wildfires that is accompanying global warming presents a real challenge to global climate change mitigation efforts.”

CAMS: monitoring extreme wildfire emissions in 2022
“Our monitoring of wildfires and vegetation fires in general shows that, at the global scale, emissions continue to decline in relation to land use changes and declining savanna fires in the tropics. However, we also continue to identify and monitor significantly increased fire emissions in different parts of the world, where hotter and drier conditions are leading to increased flammability of the vegetation”, said CAMS Senior Scientist Mark Parrington.

How wildfires in the Americas and tropical Africa in 2020 compared to previous years
“The low levels of fire activity in tropical Africa have contributed to the global total activity and carbon output being well below average. Although they can cause damage to ecosystems, human habitation and respiratory health, many of these fires burn in the savannah, were they are an important part of the ecosystem renewal.”

African burned area and fire carbon emissions are strongly impacted by small fires undetected by coarse resolution satellite data, 2021
“Fires burn an area comparable to Europe each year, emitting greenhouse gases and aerosols. We compared burned area (BA) based on 20-m resolution images with a BA derived from 500-m data. It represents an 80% increase in BA in sub-Saharan Africa, responsible for about 70% of global BA. This difference is predominately (87%) attributed to small fires (<100 ha), which account for 41% of total BA but only for 5% in coarse-resolution products.”

Trends in the annual number of large fires in the western United States
“Climate change enhances the drying of organic matter in forests (the material that burns and spreads wildfire), and has doubled the number of large fires between 1984 and 2015 in the western United States.”

Annual Mean Growth Rate of CO2 at Mauna Loa, Hawaii
CO2 Annual Increase (ppm):
0.9 in the 1960s
1.3 in the 1970s
1.5 in the 1990s
2.4 in the 2010s

“Earth’s temperature has risen by an average of 0.14° Fahrenheit (0.08° Celsius) per decade since 1880, or about 2° F in total. The rate of warming since 1981 is more than twice as fast: 0.32° F (0.18° C) per decade.”

“Tipping points are possible at today’s global warming of just over 1 °C (1.8 °F) above preindustrial times, and highly probable above 2 °C (3.6 °F) of global warming”


Unfortunately that is no longer the issue. We have very high CO2 levels now. Adding more has more of an effect. We have no room to play around.

We have zero room to play around with XOM.

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This is another example of cherry-picking the data to give an inaccurate impression of the research. Yang et al (2014) attributed most of this declining trend to changes in land use, like increased agriculture and grazing that is counterbalancing the tendency of climate change to increase fire risk. Here is a sample quote from the paper:

In the extratropics, climate influence was also important for fire activities. In the western United States, wildfire frequency has increased since the mid-1980s in response to the climate warming and extended fire season [Westerling et al ., 2006]. As demonstrated by Figure 7c, our simulation captured the upward trend of burned area in northern extratropics from the 1980s to the 2000s. Within this period, climate dominated the fire trend, and its contribution increased from −7.1 × 104 km2 yr−1 to 7.8 × 104 km2 yr−1. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2013JG002532

At the risk of oversimplification, if all fires are taken into consideration as with Yang et al, then a declining global trend is seen although rising trends can be observed in some regions. If the focus is more on wildfires associated with forests (my link), then an increasing trend in global burn acreage is observed.

To get an accurate view of what is happening, one has to look at the data in context. The overall evidence supports global warming increasing the risk of wildfires in many regions with the number of regions so impacted rising with more warming.


A couple of points:
• From a mix of causes, wildfire emissions into the atmosphere are declining, both recently (since 2003, see the graph upthread) and long-term (since 1900).
• The most recent IPCC report (AR6) has a summary chart that indicates when a given climate signal is expected to rise above the noise of variations. This is called time to emergence (Working Group 1, Chapter 12, Table 12.12). One of the categories is what they call ‘fire weather’. They show that currently “evidence is lacking or the signal is not present, leading to overall low confidence of an emerging signal.” Not only is this the case currently, but also for between now and 2050. This is also the case for between now and 2100.


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I think you might be on to something!


In the linked article, just below the graph is the following statement:

“Our monitoring of wildfires and vegetation fires in general shows that, at the global scale, emissions continue to decline in relation to land use changes and declining savanna fires in the tropics. However, we also continue to identify and monitor significantly increased fire emissions in different parts of the world, where hotter and drier conditions are leading to increased flammability of the vegetation”, said CAMS Senior Scientist Mark Parrington.

Seems likely that continued global warming will lead to more “hotter and drier conditions”.

That was then. The IPCC AR6 report used CMIP5 fire modeling, which for a variety of reasons is not particularly good on this issue. The 2022 review I linked upthread with all those fire weather curves noted this weakness and also described the effort call the Fire Model Intercomparison Project (FireMIP) to improve the fire models. The FireMIP data was not available for the AR6 report. The figure I pasted represents an advance over the AR6 report on fire weather, or as the authors put it:

Here, we explore model outputs from six FireMIP models (Hantson et al., 2020; Teckentrup et al., 2019) to illustrate the current understanding of how the global distribution of fire activity has changed over the past century…

Using FireMIP modeling they concluded the following (BA = Burn Area):

There have been increases in the length of the fire weather season and the frequency of extreme fire weather in most world regions during 1979–2019, priming landscapes to burn more frequently…During 2001–2019, we observed significant positive correlations between fire weather and BA in all ecoregions that we studied on a seasonal basis, indicating that fire weather strongly determines the annual timing of fires…Overall, correlations between BA and fire weather indicate that fire activity peaks in the seasons when fire weather is most conducive to vegetation flammability, and in some places the years with greatest BA also tend to coincide with the years of greatest fire weather. No other human or bioclimatic control on fire shares such a consistent relationship with BA as fire weather, signifying the key role of fire weather as a pervasive enabler of fire.