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Growing number of mega-fires may contribute to global warming

FAO calls for wildfire emissions monitoring and comprehensive fire management strategies

Photo: ©FAO/Roberto Faidutti
Mega-fires are mainly started by humans but are likely exacerbated by the effects of climate change.

10 May 2011, Rome/Sun City - Whilst changing climatic conditions may be exacerbating the growing number of mega-fires round the world, these fires may also themselves be a contributing factor to global warming, said FAO in a report presented today at the 5th International Wildland Fire Conference in Sun City, South Africa.

The agency called upon countries to implement more comprehensive fire management strategies and improve the monitoring of wildfire carbon gas emissions that cause global warming.

"Mega-fires are mainly caused by humans and are likely exacerbated by climate change, but now we suspect they may also in themselves represent a vicious circle that is speeding up global warming," said Pieter van Lierop, FAO Forestry Officer. "With an increasing incidence in the frequency and size of mega-fires along with weather projections indicating hotter and drier fire seasons, the issue is becoming urgent," he said.

Recent examples of mega-fires include the 2009 Black Saturday conflagration in Australia which killed 173 people and incinerated many towns, and record-setting wildfires in Russia last year, where 62 people were killed and around 2.3 million hectares burned as a result of over 32 000 fires.

The report, entitled "Findings and Implications from a Coarse-Scale Global Assessment of Recent Selected Mega-Fires", studies recent fires in Australia, Botswana, Brazil, Indonesia, Israel, Greece, Russia, and the United States.

Major causes of mega-fires

Nearly all of the mega-fires studied under this assessment were started by people. Often fires are deliberately set in order to clear land for agricultural or development purposes. Drought was implicated in all but one of the mega-fires examined. Hot, dry and windy conditions accompanied all of the wildfires studied in the report. In tropical forests, mega-fires are principally fueled by dried-out woody debris left behind from logging and land clearing for plantations and crop production. 

Balanced wildfire protection strategies needed

Although drought is often blamed for the uncontrolled spread of mega-fires, Florida and Western Australia offer two examples where, despite the prolonged presence of severe drought, wildfire costs, losses, and damages seem much lower than elsewhere. These programs reflect more balanced prevention, mitigation, and suppression approaches.

In Florida, the U.S. Forest Service and the State of Florida own approximately 800 000 hectares. On average each year, both agencies burn between 10 and 20 percent of their forests in a controlled way.  Controlled fires occur on a two- to four-year rotation and cost between $10-30 per hectare. In forests left untreated, wildfire suppression costs can often exceed many hundreds, even thousands of dollars per hectare, not counting the additional losses and damages that may be involved.

In southwest Western Australia, the Department of Environment and Conservation protects an estate of approximately 2.5 million hectares. It routinely uses controlled fires to treat approximately 8-9 percent of their holdings and aim for 70-90 percent burn coverage.  Wildfire costs, losses, and damages have been much reduced since the controlled burning program began.

In some areas, community-based fire management initiatives are underway. These models, jointly run by private and public landowners, reconcile competing interests, and provide for safer and more resilient fire-prone forests at landscape scales.