A report issued by Australia’s privately funded Climate Council has concluded that the number of professionals needed to fight bushfires in Australia will double by 2030. This major shift will be required by changes attributed to climate change. The 63-page report, titled Be Prepared: The Changing Climate and Australia’s Bushfire Threat, is entirely devoted to how climate change is already affecting wildland fires and how the rate of change is expected to increase over the next decades.
According to the report the most direct link between bushfires and climate change comes from the long-term trend towards a hotter climate. The change is increasing the frequency and severity of very hot days and driving up the likelihood of very high fire danger caused by weather. Changes in temperature and rainfall may also affect the amount and condition of fuel and the probability of lightning strikes.
The report lays out the current and predicted situation extremely well through the text and illuminating graphics. Click on the images here from the report to see larger versions.
I especially like the graphic above, which illustrates how four factors that affect wildland fire are being influenced by climate change
- Ignitions: more lightning leads to more fires;
- Fuel load will increase due to higher carbon dioxide levels, higher temperatures, and more rainfall. It could also decrease in some areas and vegetation types as a result of higher temperatures and less rain.
- Fuel condition: higher temperatures and decreasing rainfall will increase fire activity while more rain in some areas will decrease fire activity.
- Weather: higher temperatures will greatly increase fire activity.
Obviously it is a complex scenario with the factors having varying effects around the world where climate change affects local areas differently and vegetation types have specific responses to changes in weather.
The report concentrates on the effects in Australia, but also covers changes observed world-wide. As we have pointed out, in the United States there was an abrupt transition of fire activity in the mid-1980s with higher fire frequency, longer fire durations, and longer fire seasons. Fire frequency from 1987 to 2003 was nearly four times the average for 1970 through 1986. The area burned from 1987 to 2003 was more than six times that from 1970 to 1986, and the length of the fire season increased by about 2 months (Westerling et al., 2006).
The report discussed how fires affect carbon in the atmosphere:
Bushfires generate many feedbacks to the climate system, some of which can increase warming, while others decrease it. Emission of CO2 from bushfires generally represents a redistribution of existing carbon in the active carbon cycle from vegetation to the atmosphere.
As long as the vegetation is allowed to recover after a fire, it can reabsorb a very large fraction of the carbon released. By contrast, the burning of fossil fuels represents additional carbon inserted into the active land-atmosphere-ocean carbon cycle.
Increasing fire danger will make it more difficult to find times when planned prescribed fires are within the established prescriptions, which could result in fewer acres treated and higher fuel loads near wildland urban interfaces.
