Cassandra Chapman, The University of Queensland

In late 2019 and early 2020, a series of devastating wildfires, known as the “black summer” bushfire disaster, left Australia reeling: More than 20% of the country’s forests burned.

As a scholar of the psychology of charitable giving, I have long been interested in the unique emotional response that disasters evoke – often generating an urgent and visceral wish to help.

I wanted to understand how and why people respond to a crisis of this magnitude. For the project, I teamed up with three Australian environmental psychology and collective action experts: Matthew Hornsey, Kelly Fielding and Robyn Gulliver.

We found that international media coverage of disasters can help increase donations. Our findings, which were published in the peer-reviewed academic journal Disasters in 2022, are relevant to the situation in Los Angeles, where severe fires destroyed thousands of homes and businesses in January 2025, devastating many communities.

That recovery could take years.

5 key factors affect generosity

All told, Australian donors gave more than US$397 million, or $640 million in Australian dollars, to support the recovery from the black summer bushfire disaster. The international community also rallied: U.S. and U.K. donors contributed an additional US$2.6 million. These donations were used to fund evacuation centers, support groups for victims, and cash grants for repairs and rebuilding, among other things.

When we surveyed 949 Australians about what influenced their donations and analyzed news articles about the disaster, we found that coverage of disasters significantly increased generosity and influenced which charities drew donations. This may be because news articles communicated directly the need for charitable support.

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Using this survey data, we identified key factors that influenced how much money, if any, people donated in response to the bushfire disaster appeals. These five were linked with the amounts Australians donated:

• Scale: The sheer scale of the fires.

• Personal impact: Having been personally affected, knowing people who have been affected, or being worried that they will be affected in the future.

• Climate change beliefs: Believing that climate change is impacting the environment.

• News footage: The dramatic footage of the fires they have seen.

• Stories: The stories of those who have been affected.

Three of these factors – scale, news footage and stories – relate to information people were exposed to in media coverage of the disaster. Further, when we asked people how they chose which charities to support, they said that media coverage was more influential than either their friends and family or direct communication from those same charities.

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These findings collectively show how media coverage can powerfully influence both how much people give to disaster relief and which nonprofits they choose to support.

Setting the agenda

In the next phase of our research, we tried to learn how media coverage affects the public’s generosity.

We downloaded every news article we could find about the disaster over the three-month period that fires raged and analyzed the text of 30,239 news articles using Linguistic Inquiry and Word Count software.

We looked at which kinds of language and concepts were being used in media coverage, and how frequently they were used compared with their use in everyday written language.

In addition to concepts we expected to see, like emergency, heroes and human loss, we found that the concepts of support and money frequently showed up in coverage. Words like “donations,” “help” and “support” occurred in 74% of news articles. Words having to do with money were even more common: They appeared almost twice as often as they do in ordinary written language.

Our findings suggest that news coverage may have helped to set the agenda for the huge charitable response to Australia’s wildfire disaster because the media told people what they should be thinking about in terms of that disaster. In Australia’s case, it was how they could help.

A consideration for the media

We also believe that it’s likely that news coverage of disasters like this one can serve an agenda-setting function by teaching the public how to think about the crisis.

To the extent that news coverage highlights concepts like support, possibly communicating that donating is a normal response to a crisis, it’s reasonable to expect people to donate more money.

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Given that news coverage can influence how much someone donates, as well as which charities they choose to support, nonprofits responding to the Los Angeles fires may wish to encourage media outlets to mention their work in news coverage.

It is likely that being featured in news coverage – especially when calls to action or opportunities to donate are incorporated in an article – would result in more funds being raised for the charity’s response to the disaster.

Cassandra Chapman, Associate Professor, The University of Queensland

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

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Patrick Megonigal, Smithsonian Institution

Firefighters battling the deadly wildfires that raced through the Los Angeles area in January 2025 have been hampered by a limited supply of freshwater. So, when the winds are calm enough, skilled pilots flying planes aptly named Super Scoopers are skimming off 1,500 gallons of seawater at a time and dumping it with high precision on the fires.

Using seawater to fight fires can sound like a simple solution – the Pacific Ocean has a seemingly endless supply of water. In emergencies like Southern California is facing, it’s often the only quick solution, though the operation can be risky amid ocean swells.

But seawater also has downsides.

Saltwater corrodes firefighting equipment and may harm ecosystems, especially those like the chaparral shrublands around Los Angeles that aren’t normally exposed to seawater. Gardeners know that small amounts of salt – added, say, as fertilizer – does not harm plants, but excessive salts can stress and kill plants.

While the consequences of adding seawater to ecosystems are not yet well understood, we can gain insights on what to expect by considering the effects of sea-level rise.

A seawater experiment in a coastal forest

As an ecosystem ecologist at the Smithsonian Environmental Research Center, I lead a novel experiment called TEMPEST that was designed to understand how and why historically salt-free coastal forests react to their first exposures to salty water.

Sea-level rise has increased by an average of about 8 inches globally over the past century, and that water has pushed salty water into U.S. forests, farms and neighborhoods that had previously known only freshwater. As the rate of sea-level rise accelerates, storms push seawater ever farther onto the dry land, eventually killing trees and creating ghost forests, a result of climate change that is widespread in the U.S. and globally.

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In our TEMPEST test plots, we pump salty water from the nearby Chesapeake Bay into tanks, then sprinkle it on the forest soil surface fast enough to saturate the soil for about 10 hours at a time. This simulates a surge of salty water during a big storm.

Our coastal forest showed little effect from the first 10-hour exposure to salty water in June 2022 and grew normally for the rest of the year. We increased the exposure to 20 hours in June 2023, and the forest still appeared mostly unfazed, although the tulip poplar trees were drawing water from the soil more slowly, which may be an early warning signal.

Things changed after a 30-hour exposure in June 2024. The leaves of tulip poplar in the forests started to brown in mid-August, several weeks earlier than normal. By mid-September the forest canopy was bare, as if winter had set in. These changes did not occur in a nearby plot that we treated the same way, but with freshwater rather than seawater.

The initial resilience of our forest can be explained in part by the relatively low amount of salt in the water in this estuary, where water from freshwater rivers and a salty ocean mix. Rain that fell after the experiments in 2022 and 2023 washed salts out of the soil.

But a major drought followed the 2024 experiment, so salts lingered in the soil then. The trees’ longer exposure to salty soils after our 2024 experiment may have exceeded their ability to tolerate these conditions.

Seawater being dumped on the Southern California fires is full-strength, salty ocean water. And conditions there have been very dry, particularly compared with our East Coast forest plot.

Changes evident in the ground

Our research group is still trying to understand all the factors that limit the forest’s tolerance to salty water, and how our results apply to other ecosystems such as those in the Los Angeles area.

Tree leaves turning from green to brown well before fall was a surprise, but there were other surprises hidden in the soil below our feet.

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Rainwater percolating through the soil is normally clear, but about a month after the first and only 10-hour exposure to salty water in 2022, the soil water turned brown and stayed that way for two years. The brown color comes from carbon-based compounds leached from dead plant material. It’s a process similar to making tea.

Our lab experiments suggest that salt was causing clay and other particles to disperse and move about in the soil. Such changes in soil chemistry and structure can persist for many years.

Sea-level rise is increasing coastal exposure

While ocean water can help fight fires, there are reasons fire officials prefer freshwater sources – provided freshwater is available.

U.S. coastlines, meanwhile, are facing more extensive and frequent saltwater exposure as rising global temperatures accelerate sea-level rise that drowns forests, fields and farms, with unknown risks for coastal landscapes.

Patrick Megonigal, Associate Director of Research, Smithsonian Environmental Research Center, Smithsonian Institution

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

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Virginia Iglesias, University of Colorado Boulder

Investigators are trying to determine what caused several wind-driven wildfires that have destroyed thousands of homes across the Los Angeles area in January 2025. Given the fires’ locations, and lack of lightning at the time, it’s likely that utility infrastructure, other equipment or human activities were involved.

California’s wildfires have become increasingly destructive in recent years. Research my colleagues and I have conducted shows U.S. wildfires are up to four times larger and three times more frequent than they were in the 1980s and ’90s. Fast-moving fires have been particularly destructive, accounting for 78% of structures destroyed and 61% of suppression costs between 2001 and 2020.

Lightning strikes are a common cause of U.S. wildfires, but the majority of wildfires that threaten communities are started by human activities.

A broken power line started the deadly 2023 Maui fire that destroyed the town of Lahaina, Hawaii. Metal from cars or mowers dragging on the ground can spark fires. California’s largest fire in 2024 started when a man pushed a burning car into a ravine near Chico. The fire destroyed more than 700 homes and buildings.

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What makes these wildfires so destructive and difficult to contain?

The answer lies in a mix of wind speed, changing climate, the legacy of past land-management practices, and current human activities that are reshaping fire behavior and increasing the risk they pose.

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Fire’s perfect storm

Wildfires rely on three key elements to spread: conducive weather, dry fuel and an ignition source. Each of these factors has undergone pronounced changes in recent decades. While climate change sets the stage for larger and more intense fires, humans are actively fanning the flames.

Climate and weather

Extreme temperatures play a dangerous role in wildfires. Heat dries out vegetation, making it more flammable. Under these conditions, wildfires ignite more easily, spread faster and burn with greater intensity. In the western U.S., aridity attributed to climate change has doubled the amount of forestland that has burned since 1984.

Compounding the problem is the rapid rise in nighttime temperatures, now increasing faster than daytime temperatures. Nights, which used to offer a reprieve with cooler conditions and higher humidity, do so less often, allowing fires to continue raging without pause.

Finally, winds contribute to the rapid expansion, increased intensity and erratic behavior of wildfires. Wind gusts push heat and embers ahead of the fire front and can cause it to rapidly expand. They can also create spot fires in new locations. Additionally, winds enhance combustion by supplying more oxygen, which can make the fire more unpredictable and challenging to control. Usually driven by high winds, fast-moving fires have become more frequent in recent decades.

Fuel

Fire is a natural process that has shaped ecosystems for over 420 million years. Indigenous people historically used controlled burns to manage landscapes and reduce fuel buildup. However, a century of fire suppression has allowed vast areas to accumulate dense fuels, priming them for larger and more intense wildfires.

Invasive species, such as certain grasses, have exacerbated the issue by creating continuous fuel beds that accelerate fire spread, often doubling or tripling fire activity.

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Additionally, human development in fire-prone regions, especially in the wildland-urban interface, where neighborhoods intermingle with forest and grassland vegetation, has introduced new, highly flammable fuels. Buildings, vehicles and infrastructure often ignite easily and burn hotter and faster than natural vegetation. These changes have significantly altered fuel patterns, creating conditions conducive to more severe and harder-to-control wildfires.

Ignition

Lightning can ignite wildfires, but humans are responsible for an increasing share. From unattended campfires to arson or sparks from power lines, over 84% of the wildfires affecting communities are human-ignited.

Human activities have not only tripled the length of the fire season, but they also have resulted in fires that pose a higher risk to people.

Lightning-started fires often coincide with storms that carry rain or higher humidity, which slows fires’ spread. Human-started fires, however, typically ignite under more extreme conditions – hotter temperatures, lower humidity and stronger winds. This leads to greater flame heights, faster spread in the critical early days before crews can respond, and more severe ecosystem effects, such as killing more trees and degrading the soil.

Human-ignited fires often occur in or near populated areas, where flammable structures and vegetation create even more hazardous conditions. Homes and the materials around them, such as wooden fences and porches, can burn quickly and send burning embers airborne, further spreading the flames.

As urban development expands into wildlands, the probability of human-started fires and the property potentially exposed to fire increase, creating a feedback loop of escalating wildfire risk.

Whiplash weather

A phenomenon known as whiplash weather, marked by unusually wet winters and springs followed by extreme summer heat, was especially pronounced in Southern California in recent years.

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A wet spring in 2024 fostered vegetation growth, which then dried out under scorching summer temperatures, turning into highly combustible fuel. This cycle fueled some of the biggest fires of the 2024 season, several of which were started by humans.

That dryness continued in Southern California through the fall and into early winter, with very little rainfall. Soil moisture in the Los Angeles region was about 2% of historical levels for that time of year when the fires began on Jan. 7, 2025.

As the factors that can drive wildfires converge, the potential for increasingly severe wildfires looms ever larger. Severe fires also release large amounts of carbon from trees, vegetation and soils into the atmosphere, increasing greenhouse gas emissions and exacerbating climate change, contributing to more extreme fire seasons.

This is an update to an article originally published Oct. 8, 2024.

Virginia Iglesias, Interim Earth Lab Director, University of Colorado Boulder

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

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