³Ô¹ÏÍøÕ¾

People have been using fire for millennia. It is a vital part of many ecosystems and cultures. Yet human activities in the current era, sometimes called the ““, are reshaping patterns of fire across the planet.

, published in the Annual Review of Environment and Resources, we used satellite data to create global maps of where and how fires are burning. We calculated about 3.98 million square kilometres of Earth’s land surface burns each year. We also examined research spanning archaeology, climatology, ecology, Indigenous knowledge and paleoecology, to better understand the causes and consequences of fires.

Our international team found strong evidence fires are burning in unexpected places, at unusual times and in rarely observed ways. These changes in fire patterns are threatening human lives and modifying ecosystems.

But the future does not have to be bleak. There are many opportunities to apply knowledge and practice of fire to benefit people and nature.

Here’s how fire patterns are changing

Exploring multiple approaches and scales enables a deeper understanding of where, when and how fires burn.

Satellite data provide evidence of changes in fire patterns at a global scale. increased by 14 days from 1979 to 2020 and , which indicate fires that cannot be quickly controlled, increased in intensity by 7.2% from 2003 to 2020.

Other changes are apparent only when we look at data from particular regions. An increase in fire size and the frequency of large fires has recently been observed in . Meanwhile fire-dependent grasslands and savannahs across and have experienced reductions in fire frequency.

It’s also important to consider the timescale and type of fire when interpreting changes. In Australia, the frequency of very large forest fires has increased over the past four decades. At longer time scales, indicate the frequency of low-intensity fires following British colonisation in 1788.

Changes in fire affect air, land and water

Many animals and plants have evolved strategies that enable them to thrive under particular fire patterns. This means changes to fire characteristics can .

are reducing the available forest habitat preferred by the greater glider. But a . Threatened species of native rodents can benefit from food resources and habitats that flourish shortly after fire.

There is evidence that emissions from recent fires are already modifying the atmosphere. The historically exceptional 2019-20 Australian wildfires produced over the Southern Hemisphere, as well as substantial carbon emissions.

The of the 2019-20 wildfires in Australia included an estimated 429 smoke-related premature deaths as well as 3,230 hospital admissions for cardiovascular and respiratory disorders.

Changes in fire patterns are modifying water cycles, too. In the western United States, and having strong impacts on and water availability.

New studies are revealing how the air, land and water that support life on Earth are connected by fires. Smoke plumes from the 2019-20 Australian wildfires transported nutrients to the Southern Ocean, resulting in .

Humans are responsible for the changes

Human drivers such as climate change, land use, fire use and suppression, and transportation and extinction of species .

Increasing global temperatures and more frequent heatwaves and droughts increase the likelihood of fire by promoting hot, dry and windy conditions. A pattern of extreme fire weather outside of natural climate variation is already emerging in , and .

Humans modify fire regimes by changing land use for agricultural, forestry and urban purposes. Until recent decades, large fires in tropical forests were uncommon. But used to clear primary forest for agriculture often promotes more frequent and intense uncontrolled fires.

Humans have transported plants and animals across the globe, resulting in novel mixes of species that modify fuels and fire regimes. In many parts of the world, have increased flammability and fire activity.

Social and economic changes propel these drivers. Colonisation by Europeans and the displacement of Indigenous peoples and their skilful use of fire has been linked with fire changes in , and .

Using knowledge and practice of fire to achieve sustainability goals

represent challenges to humanity, but knowledge and practice of fire can help to achieve sustainability goals.

This includes:

• , by supporting community-owned solutions and fire practices that increase social cohesion and health
• , by designing green firebreaks and mixed-use areas with low fuels, strategically located in the landscape
• ,
  by tailoring use of fire to promote and restore species and ecosystems
• ,
  by applying low-intensity fire to promote the stability of soil organic matter and increase carbon storage
• , by allocating resources before, during, and after wildfires to at-risk communities and residents.

As the world changes, society as a whole needs to keep learning about the interplay between people and fire.

A deep understanding of fire is essential for achieving a sustainable future – in other words, .

Luke Kelly receives funding from the Australian Research Council, Victorian Department of Energy, Environment and Climate Action, Natural Hazards Research Australia, and NSW Department of Planning and Environment.

David Bowman receives funding from the Australian Research Council, Natural Hazards Research Australia, and NSW Department of Planning and Environment.

Ella Plumanns Pouton receives funding from the Australian Research Training Program, the Victorian Department of Energy, Environment and Climate Action, and Natural Hazards Research Australia.

Grant Williamson receives funding from the Australian Research Council, Natural Hazards Research Australia, and NSW Department of Planning and Environment.

Michael-Shawn Fletcher receives funding from the Australian Research Council.