Loading the Climate Dice:  Wildfires & Global Warming

Professor Jeff Obbard

Recent wildfires, notably in California, Spain and Portugal reveal the growing vulnerability of natural ecosystems and human habitation to ongoing climate change. Nothing left but ‘ash and bones’ was the grim description of the aftermath wildfires that swept through Northern California in mid-October that killed at least 38 people and destroyed over 5,000 homes. Later in October, at least another 36 people died as hundreds of fires spread across central and northern areas of Portugal, fanned by strong Atlantic winds from Hurricane Ophelia. This came after an earlier devastating wildfire in Portugal in June which killed 64 people. Across the border in Spain, in Galicia, at least another 3 people died in the most recent wildfires. Although ‘fire season’ is part of life in the post summer semi-arid, warm climates of California, Spain and Portugal, the recent wildfires have been unprecedented.

Fire needs three things to sustain it: fuel, oxygen and heat. Low rainfall causing drought, searing hot temperatures and wind come together to make the perfect recipe for a conflagration. Weather cycles, such as El-Niño events naturally affect levels of precipitation and moisture, and lead to year-by-year variability in the potential for droughts and wildfires. Although no single wildfire can be attributed to climate change, the gradual warming of the planet has now loaded the ‘climate dice’ – where the chance of extreme summer temperatures occurring in any one year is becoming greater. Compared to a 1950-1980 baseline period, the area of the Earth’s land surface now experiencing extreme summer heat has expanded by over 50-times. Such conditions increase the likelihood that, once wildfires are started by lightning strikes or human error, they will be more intense and longer-burning. Indeed, a recent study published in the Proceedings of the National Academy of Sciences indicate that climate change has already played a significant role in making forests in the western U.S. drier and more likely to burn –  nearly doubling the area affected by forest fires over the last three decades. As wildfires become more frequent and intense, the carbon emissions they release will exacerbate the speed of climate change – leading to a feedback loop where more warming leads to more fires, which releases more carbon, which causes more warming, and so on.

This ‘runaway train’ of climate change is of special concern in Southeast Asia where forest fires also release massive amounts of greenhouse gases when the heavy deposits of carbon-rich peat also burn beneath them. As we know in Singapore, the environmental and health costs of wildfires go beyond just the loss of biodiverse ecosystems. Wildfires can rapidly increase local air pollution – exacerbating lung diseases, and causing breathing difficulties – even in healthy individuals.  The costs of wildfires, in terms of risks to human life and health, property damage and forests will only increase unless we tackle climate change.