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Discovery: Massive amounts of methane gas spews from wildfires

Scientists at the University of California, Riverside (UCR) have discovered that wildfires are releasing a massive amount of methane gas into the atmosphere. Methane is a greenhouse gas much more potent than carbon dioxide. This source of methane was previously unaccounted for. It could make it challenging for states to achieve their cleaner air and climate goals.

Methane gas is known to warm the planet 86 times more effectively than carbon dioxide over a 20-year period. It is currently not being tracked by state air quality managers when it comes to emissions from wildfires. This omission could have significant implications for climate change mitigation efforts.

Wildfires have long been known to emit methane gas. A new study conducted by UCR researchers reveals that the amount of methane released by the top 20 fires in 2020 was more than seven times the average from wildfires in the previous 19 years. This significant increase in emissions has been linked to the growing size and intensity of fires.

“Fires are getting bigger and more intense, and correspondingly, more emissions are coming from them,” explained study co-author Professor Francesca Hopkins. She added that the fires in 2020 would have accounted for 14 percent of the state’s methane budget, had they been tracked.

Monitoring sources of methane gas

Currently, the state does not monitor natural sources of methane gas, such as those produced by wildfires. However, the 2020 wildfires would have ranked as the third biggest source of methane in the state. 

Professor Hopkins emphasized the importance of addressing these emissions, stating: “Typically, these sources have been hard to measure, and it’s questionable whether they’re under our control. But we have to try. They’re offsetting what we’re trying to reduce.”

In the past, scientists measured emissions by analyzing air samples collected from wildfires using aircraft. However, this method is both costly and complex. The UCR research team, however, employed a remote sensing technique to measure emissions from the Sequoia Lightning Fire Complex in the Sierra Nevadas. This remote sensing method is not only safer for scientists but also potentially more accurate. It captures an integrated plume from the fire, including different burning phases.

The novel technique, detailed in the journal Atmospheric Chemistry and Physics, allowed lead author and UCR environmental sciences Ph.D. student Isis Frausto-Vicencio to safely measure the entire plume of gas and debris from the Sequoia Lightning Fire Complex from 40 miles away.

“The plume, or atmospheric column, is like a mixed signal of the whole fire, capturing the active as well as the smoldering phases,” said Professor Hopkins. “That makes these measurements unique.”

Study used a new method to measure methane gas

The study employed a novel technique that utilizes the sun as a light source instead of lasers. This approach is common in similar instruments.

The innovative technique works by using the sun’s heat energy absorbed and emitted by gases in the plume. This allows scientists to determine the quantity of aerosols, carbon, and methane gas present. This method enabled the research team to measure the massive amount of methane released by the Sequoia Lightning Fire Complex. The 20 gigagrams of methane detected is noteworthy. Just one gigagram is equal to 1,000 metric tons, and an elephant weighs around one metric ton.

Interestingly, the data obtained using this remote technique corresponds with measurements collected from European space agency satellite data. While these satellites offer a broader, global view of burned areas, they are not yet capable of measuring methane gas in such conditions.

The study’s findings have critical consequences for California’s methane budget, as established by the California Air Resources Board. If wildfires like the Sequoia Lightning Fire Complex were accounted for, they would surpass residential and commercial buildings, power generation, and transportation in terms of methane emissions. 

However, they would still rank behind agriculture and industry. As climate change continues to intensify, scientists predict that more megafire years will occur in the future. This will further exacerbate methane emissions.

Addressing methane gas emissions

California has been proactive in addressing methane gas emissions since 2015 when the state set a target to reduce methane, refrigerants, and other air pollutants contributing to global warming by 40% by 2030. In 2016, Gov. Jerry Brown signed SB 1383 into law, officially codifying these reduction targets. 

The state’s ambitious goals are to be achieved through a series of regulations aimed at capturing methane gas from dairy farm manure, minimizing leaks from oil and gas producers, eliminating food waste in landfills, banning specific gases in new refrigerators and air conditioners, and implementing other measures.

“California has been way ahead on this issue,” said Professor Hopkins. “We’re really hoping the state can limit the methane emissions under our control to reduce short-term global warming and its worst effects, despite the extra emissions coming from these fires.”

The research highlights the importance of understanding and addressing the role of wildfires in methane emissions. This is particularly important in regions like California, which are already grappling with the impacts of climate change. By doing so, the state can make informed decisions on how best to mitigate greenhouse gas emissions and adapt to an increasingly unpredictable climate.

More about wildfires

Wildfires have a significant impact on humans and the environment, with consequences that can be both immediate and long-lasting. Some key aspects of wildfires and their effects are as follows:

Air quality

Wildfires produce smoke, which contains a mixture of gases, such as methane gas, and fine particles. These can cause respiratory issues, aggravate pre-existing conditions such as asthma and chronic obstructive pulmonary disease (COPD), and contribute to heart problems. Smoke can travel great distances, affecting air quality in regions far from the actual fire.

Climate change

Wildfires release large amounts of greenhouse gases, such as carbon dioxide (CO2) and methane (CH4), into the atmosphere. This contributes to global warming and climate change, which in turn can lead to more frequent and severe wildfires. Additionally, the loss of forests and vegetation due to wildfires reduces the Earth’s ability to absorb CO2, further exacerbating climate change.

Loss of biodiversity

Wildfires can cause significant damage to ecosystems, killing plants and animals, and reducing biodiversity. In some cases, wildfires can lead to the local extinction of sensitive species. Moreover, the loss of habitat can make it challenging for the surviving wildlife to find food, shelter, and breeding grounds.

Soil erosion and water quality

Wildfires can remove vegetation that helps stabilize soil and prevent erosion. This can lead to increased sedimentation in rivers and streams, affecting water quality and aquatic habitats. Additionally, the chemicals and ash released during a wildfire can contaminate water sources, posing risks to both humans and wildlife.

Economic impact

Wildfires can cause considerable damage to property, infrastructure, and natural resources, resulting in substantial economic losses. The costs of fighting wildfires, as well as the subsequent rebuilding and restoration efforts, can strain government budgets and local economies.

Mental health

Wildfires can have psychological effects on individuals and communities. The stress and trauma associated with losing one’s home, witnessing the devastation of the landscape, and the loss of livelihood can lead to mental health issues such as anxiety, depression, and post-traumatic stress disorder (PTSD).

Carbon sequestration

Forests play a crucial role in capturing and storing carbon, helping to mitigate climate change. Wildfires can reduce the carbon sequestration capacity of forests, especially when fires become more frequent or severe, preventing forests from regenerating and capturing carbon effectively. By releasing tons of methane gas, the climate impact becomes substantially worse.

To minimize the impacts of wildfires on humans and the environment, it is essential to implement effective forest management practices, promote public awareness and preparedness, and develop strategies to mitigate climate change.


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