Western Wildfires Are Spinning Off Tornadoes – Here’s How Fires Create Their Own Freakish Weather

Fire tornado damage: WAPA's steel infrastructure mostly survived the fire intact, with one exception: the site of the fire tornado in Redding, July 26. The fire tornado destroyed at least three steel structures, including ripping two from the ground. Image by Western Area Power (Staff photo) (CC BY 2.0).
Fire tornado damage: WAPA’s steel infrastructure mostly survived the fire intact, with one exception: the site of the fire tornado in Redding, July 26. The fire tornado destroyed at least three steel structures, including ripping two from the ground. Image by Western Area Power (Staff photo) (CC BY 2.0).

By Charles Jones, Professor of Atmospheric Science, University of California, Santa Barbara and Leila Carvalho, Professor of Meteorology and Climatology, University of California, Santa Barbara. Published in collaboration with The Conversation (Public License).

It might sound like a bad movie, but extreme wildfires can create their own weather – including fire tornadoes.

It happened in California as a heat wave helped to fuel hundreds of wildfires across the region, many of them sparked by lightning. One fiery funnel cloud on Aug. 15 was so powerful, the National Weather Service issued what’s believed to be its first fire tornado warning.

So, what has to happen for a wildfire to get so extreme that it spins off tornadoes?

As professors who study wildfires and weather, we can offer some insights.

How Extreme Fire Conditions Form

Fires have three basic elements: heat, fuel and oxygen.

In a wildland fire, a heat source ignites the fire. Sometimes that ignition source is a car or power line or, as the West saw in mid-August, lightning strikes. Oxygen then reacts with dry vegetation to produce heat, ash and gases. How dry the landscape is determines whether the fire starts, how fast it burns and how hot the fire can get. It’s almost as important as wind.

Fire weather conditions get extreme when high temperatures, low humidity and strong winds combine with dead and live vegetation to produce difficult-to-fight, fast-spreading wildfires.

That combination is exactly what the West has been seeing. A wet winter fed the growth of grasses that now cover large areas of wildland in the western U.S. Most of this grass is now dead from the summer heat. Combined with other types of vegetation, that leaves lots of fuel for the wildfires to burn.

The remnants of Hurricane Elida also played a role. The storm increased moisture and instability in the atmosphere, which triggered thunderstorms further north. The atmosphere over land was pretty dry by then, and even when rain formed at the base of these clouds, it mostly evaporated due to the excessive heat. This led to “dry lightning” that ignited wildfires.

Wildfires Can Fuel Thunderstorms

Fires can also cause convection – hot air rises, and it moves water vapor, gases and aerosols upward.

Wildfires with turbulent plumes can produce a “cumulus” type of cloud, known as pyrocumulus or pyrocumulonimbus. Pyrocumulus clouds are similar to the cumulus clouds people are used to seeing. They develop when hot air carries moisture from plants, soil and air upward, where it cools and condenses. The centers of these “pyroclouds” have strong rising air.

It’s pretty common, and it’s a warning sign that firefighters could be facing erratic and dangerous conditions on the ground from the indraft of air toward the center of the blaze.

In some cases, the pyroclouds can reach 30,000 feet and produce lightning. There is evidence that pyrocumulus lightning may have ignited new blazes during the devastating fire storm in Australia in 2009 known as “Black Friday.”

Where do fire tornadoes come from?

Similar to the way cumulonimbus clouds produce tornadoes, these pyroclouds can produce fire‐generated vortices of ash, smoke and often flames that can get destructive.

A vortex can form because of the intense heat of the fire in an environment with strong winds. This is similar to a strong river flow passing through a depression. The sudden change in the speed of the flow will force the flow to rotate. Similarly, the heat generated by the fire creates a low pressure, and in an environment with strong winds, this process results in the formation of a vortex.

One fire tornado, or fire whirl, that developed during the deadly 2018 Carr Fire devastated parts of Redding, California, with winds clocked at over 143 miles per hour.

These vortices can also increase the severity of the fires themselves by sucking air rich in oxygen toward the center of the vortex. The hotter the fire, the higher the probability of stronger updrafts and stronger and larger vortices.

Persistent heat waves that dry out the land and vegetation have increased the potential of wildfires to be more violent and widespread.

Is extreme fire weather becoming more common?

Global warming has modified the Earth’s climate in ways that profoundly affect the behavior of wildfires.

Scientific evidence suggests that the severity of prolonged droughts and heat waves has been exacerbated not only by rising temperatures but also by changes in atmospheric circulation patterns associated with recent climate change. These changes can enhance extreme fire-weather behavior.

A study published Aug. 20 found that the frequency of California’s extreme fire weather days in the autumn fire season had more than doubled since the early 1980s. Over that four-decade period, autumn temperatures in the state rose by about 1.8 degrees Fahrenheit and autumn precipitation decreased by about 30%.

Firefighters and people living in wildfire-prone areas, meanwhile, need to be prepared for more extreme wildfires in the coming years.

The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Disclosure statement: Charles Jones receives funding from the National Science Foundation and the University of California. Leila Carvalho receives funding from the National Science Foundation.

Environmental Injustice is Rampant Around the World

A study of nearly 700 studies makes it clear: Environmental injustice is rampant around the world

By Rishi Sugla, AAAS Mass Media Fellow, ensia (CC BY-ND 3.0)

August 10, 2020 (originally appeared in ensia on July 30, 2020) — The coronavirus pandemic and resurgence of the Black Lives Matter movement have many environmentalists paying attention to the inextricable links between marginalized peoples and environmental pollution.

The history of disproportionate environmental impacts on Black, Indigenous, and people of color often goes back for centuries. A recent review of 141 Indigenous groups by University of Helsinki conservation researcher Álvaro Fernández-Llamazares and colleagues published in the journal Integrated Environmental Assessment and Management shows how colonialism directly led to the development of environment-polluting infrastructure built without the consent of — and differentially affecting — communities in their territories.

The study, which dug through nearly 700 studies covering six continents to reveal impacts of pollution on the environment, health and culture of Indigenous peoples, points out that this pattern continues today.

Photo by Alev Takil on Unsplash

“The literature reviewed clearly shows that [Indigenous peoples] are among the populations at highest risk of impact by environmental pollution of water, land, and biota through both exposure and vulnerability,” the authors wrote.

The study notes that landfillspipelines, toxic waste storage facilities, sources of radioactive contamination and mines are still being forced upon Indigenous people and directly affect community well-being. In Canada, for example, 20% of drinking water advisories come from Indigenous communities, which make up just 5% of the population. In the western United States, more than 600,000 Native people live within 10 kilometers (6 miles) of an abandoned mine.

Pollution from industrial activities literally flows through Indigenous environments. Contaminants from mines and factories can move into the water, air and soil, where they affect the flora and fauna Indigenous people rely on for traditional hunting, fishing and gathering. Exposure to contaminants has been associated with stark impacts on health.

“Indigenous peoples are particularly vulnerable to the impacts of pollution due to their high and direct dependency on local natural resources, limited access to health care, and relatively low levels of governmental support,” the authors say. Diabetes, hypertension, childhood leukemia, autism, cardiovascular disease, neurological impacts, anemia, cancer, changes in age of menstruation, contaminants in breast milk and anxiety all have been associated with polluting practices on Indigenous territories, the study reports.

Many impacts, however, are not easily measured. The authors write, “While cultural impacts have often been overlooked, the literature suggests that they are substantial in extent and scope.” Environmental degradation, the study notes, has led to the gradual loss of traditional cultural practices that rely on local plants and animals that Indigenous communities hold sacred. Ceremonies that involve drinking water from historical sources can heighten exposure to contaminants. Traditional basket-weaving practices that involve holding reeds in the mouth can become a health risk, for example.

Pollution also affects the spiritual and social health of Indigenous communities. Societal roles are often intimately related to the complex relationships Indigenous peoples have with their environment. Language, culture and community roles surrounding subsistence activities have been abandoned due to contamination and degradation. Spiritual practices involving sacred water sources or sites have similarly been left unviable because of environmental pollutants.

At the same time it documented adverse impact on Indigenous peoples of exposure to contaminants and toxins that they, for the most part, did not create, the study also noted positive impacts Indigenous people have on the environment. Indigenous peoples around the world campaign and resist polluting activities through protests, resistance, demands for policy action and occupation of pollution-producing infrastructure. Many Indigenous communities lead the way at preventing environmental destruction through their direct actions as part of networks of scientists, activists and others, tapping into legal systems when possible. While often framed in public discourse simply as struggles against pollution, the study notes that these actions are directly related to issues of Indigenous sovereignty, justice and land rights.

The study also underscores how traditional management systems help prevent pollution. Indigenous spirituality and social structures tied to the environment protect, remediate and restore sacred sites and community areas. In some cases, these practices have been shown to even support recycling of nutrients in local ecosystems, and Indigenous water cultures have been key to preventing pollution in freshwater environments.

The study concludes that Indigenous people, like many marginalized or oppressed communities, are on the receiving end of disproportionate impacts of environmental pollution. At the same time, these communities are not just victims of pollution. They have long led resistance against pollution-generating industries and activities and worked to protect biodiversity around the world. To reduce the toll of pollution and to maximize the benefits of their environment-protecting actions, the researchers recommend bringing Indigenous people and their perspectives front and center in environmental action.

“Greater engagement of IPs on environmental governance can help to incorporate IPs’ social, spiritual, and customary values in environmental quality and ecosystem health,” they write. “We argue that IPs should be part of any conversation on policy options to reduce risks of pollution to human well‐being, ecosystem services, and biodiversity.”

COVID-19 Mortality Link to Air Pollution

New research links COVID-19 mortality to air pollution – specifically, small increases in levels of fine particulate matter – explains Professor Francesca Dominici from the Harvard T.H. Chan School of Public Health.

The study is the first to look at the link between long-term exposure to fine particulate air pollution (PM2.5)—generated largely from fuel combustion from cars, refineries, and power plants—and the risk of death from COVID-19 in the U.S.

The study concludes that a small increase in long-term exposure to PM2.5 leads to a large increase in the COVID-19 death rate. The results underscore the importance of continuing to enforce air pollution regulations to protect human health both during and after the COVID-19 crisis. The data and code are publicly available.