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Increased CO2 is making wildfires more frequent by making plants grow faster

We tend to think of wildfires as being caused by hot weather and drought. And for good reason – those weather conditions make plants tinder-dry. But a new study from the University of California, Riverside is flipping that idea on its head. Turns out, the biggest culprit in mega wildfires might be something utterly invisible: carbon dioxide (CO2).

CO2 and wildfires

You already know that CO2 is a greenhouse gas, trapping heat and contributing to climate change. But here’s the twist: CO2 is also a key ingredient in photosynthesis. Plants use sunlight, water, and carbon dioxide to create sugars, which fuel their growth.

With the massive increase of CO2 in our atmosphere from burning fossil fuels, we’ve essentially been putting plants on a supercharged fertilizer program. This has led to a surge in the growth of trees, shrubs, and grasses – a phenomenon scientists sometimes refer to as “global greening.”

Now, here’s the concerning part: all that extra vegetation becomes fuel for potential fires, especially during hot and dry conditions. And it’s not just the sheer amount of vegetation; the types of plants that thrive in higher CO2 environments can often be more flammable.

This means that in many areas, we have a dangerous combination: more plants overall, plus plants that are naturally prone to burning. “It’s not because it’s hotter that things are burning, it’s because there’s more fuel, in the form of plants,” said James Gomez, the lead researcher on the study.

Wildfires raging out of season

The researchers didn’t just theorize this – they put their ideas to the test using rigorous computer simulations. These simulations allowed them to isolate the influence of rising CO2 levels on vegetation and fire activity, separate from other factors that contribute to climate change.

One key lesson that emerged is that the usual “fire season” might be getting irrelevant. Of course, wildfires still thrive under hot, dry, and windy conditions – those factors make it easier for flames to spread rapidly.

However, the simulations highlight that the sheer amount of available fuel, thanks to CO2-boosted plant growth, is now the primary driver behind the terrifying scale of megafires.

James Gomez pointed to the massive wildfire in Texas this past February, which scorched over one million acres, as a stark example of this new reality.

Traditionally, wildfires of that size would be unexpected outside of the peak summer fire season. This event demonstrates that we’ve entered uncharted territory where devastating wildfires can erupt at almost any time of the year if the right combination of fuel and weather conditions exist.

Reduce CO2 and its impact on wildfires

The big takeaway of this study is sobering. It underscores that while smart fire management techniques, such as prescribed burns to carefully reduce flammable vegetation, are still absolutely crucial, they’re essentially a band-aid solution on a much larger problem.

The researchers make their stance unmistakably clear: the best way to decrease wildfires is to mitigate our carbon dioxide emissions. We need more emission control now.

This requires a fundamental shift away from our reliance on fossil fuels and investment in cleaner, sustainable energy sources on a global scale. The time for half-measures and gradual change is over.

Delaying decisive action will only further exacerbate the wildfire crisis, leading to more destruction, displacement, and potential loss of life. The science is clear – we need bold and urgent emission control measures now.

Factors leading to wildfires beyond CO2

Some additional concepts explored in the study include:

Don’t underestimate drying

While rising CO2 levels are driving increased plant growth and fuel load, it’s important to acknowledge that hotter temperatures still play a significant role in wildfires.

Increased heat from climate change dries out existing vegetation, making it significantly more flammable. This underscores the interconnectedness of climate factors, even when one might have a more dominant influence than others.

Plants aren’t all created equal

The impact of CO2 on vegetation isn’t uniform. Some plant species exhibit a stronger growth response to higher CO2 concentrations than others.

The scientists carefully considered these variations across different plant types when designing and running their models, ensuring a more realistic portrayal of wildfire behavior and CO2 amount.

This isn’t a pass for inaction

The study’s laser-focus on how changing CO2 levels impact wildfires is designed for scientific precision, isolating that particular variable. However, it’s crucial to remember that climate change is a complex issue driven by a multitude of factors, including other greenhouse gases and human activities such as land-use changes.

This study in no way suggests we ignore these other contributors; rather, it highlights the urgent need to reduce CO2 emissions alongside other climate mitigation strategies.

The study is published in the journal Communications Earth & Environment.


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