Monday, February 10, 2020

Climate Change Is Causing Wildfires. Yes, Really.

I'll admit it.  The title of this post was clickbate.  Climate change doesn't cause wildfires... at least, not directly. But it certainly contributes to all of the conditions that feed wildfires, and that is what today's post is about.

Be forewarned: this is what my writing looks like when it's "forced."  I'm not entirely sure the structure here is as rock-solid as it could be, or that the transitional flows from one paragraph to the next are seamless.

I wrote this in response to a prompt for class.  The prompt: Please write an 800 word analysis on a topic of your choosing. Please remember: a news analysis is meant to examine, explain, illuminate, and suggest new and different ways of thinking about a topic than a straightforward news report. Analyses are not advocacy in the sense that they are prescriptive calls for action.

The professor advised us that news analyses often answer the question "how" or "why" about a breaking news story, and aim to answer that.  I had been thinking about the Australian brushfires, and decided to answer my own question: how does climate change actually cause wildfire?  The answer is below.

The view in Lake Conjola, South New Wales

The Australian brushfires of 2019 - 2020 received international attention as they grew into the nation’s largest wildfires on record, burning over 15 million acres of land and destroying over 6,000 buildings, almost half of them residential. The reasons cited for the fires include an intense heatwave and drought, but the severity of these conditions can be traced back to global warming. Climate change promotes conditions that affect the likelihood of wildfires, such as heat and dryness, and scientists have been able to draw a strong causative relationship between rising global temperatures and an increase in the frequency and severity of wildfires worldwide.

The first factor in Australia’s record wildfires was the extreme heat. 2019 was Australia’s warmest year on record. Over the past century, Australia’s climate has shifted by about one and a half degrees Celsius, according to the Australian Bureau of Meteorology. Intense heat waves have begun to occur more regularly, and are often coupled with drought.

2019 was also Australia’s driest year on record; rainfall was 40% lower than average. Drought is not uncommon in Australia; its lower elevation and uniform landmass, aided by the cold ocean currents that move in from the South Pacific, prevent evaporation from occurring inland. This prevents rain cloud formation. Another factor in preventing rainfall is high-pressure systems, particularly prevalent in the southwestern area of the continent. Drought increases the probability of brushfires by drying out vegetation, creating a ready source of fuel for wildfires and lowering the ignition threshold. Coupled with intense heat and electrical storms that can spark fires, Australia’s dry season is also called “brushfire season” because of the likelihood of uncontrolled wildfires.

The heat from the fires melted the rims off of this car.

A third consequence of the rising global temperature for Australia is higher summer temperatures, which result in an earlier onset of spring. This begets a more rapid melting of spring snowpack, which in turn causes the topsoil to dry out earlier and remain dry longer. The dry soil contributes to the dryness of the brush. The spring snowpack is also melting more rapidly simply because there is less of it; Australian rainfall has declined since 1970 in the southwest, and the below-average winter rainfall reduces the spring snowpack. Having a small spring snowpack that can be rapidly melted in high temperatures makes spring come on more rapidly and lasts longer.

Longer, hotter summers and longer, warmer springs have a fourth consequence that impacts wildfire likelihood: insect populations that thrive in warmer temperatures have exploded. The Fourth National Climate Assessment, which studies global climate change but predominantly focuses on North America, notes that warmer temperatures and longer springs allow beetle populations to grow unchecked. Typically, cold climates limit their numbers; left unregulated, tree beetles and other insects negatively impact plant growth in forests, killing off new tree growth and susceptible forest populations, which, once dead, dry rapidly and act as kindling in wildfires.

A man and his dog watch their ranch burn.

Australia’s most populous state, New South Wales, was the most significantly impacted by the wildfires and exemplifies how the changing global climate can contribute to the severity of wildfires. The 2019 brushfire was the state’s worst fire on record, both in terms of the area it affected (9.9 million acres) and how long it burned. 25 of the 35 fatalities from the fire were in this state. New South Wales has also experienced the most significant drought conditions in Australia, with rainfall 77% below average. Rainfall in New South Wales has decreased overall by 10 - 20% over the last fifty years.

Narrowing the scope even further, an example of how global climate change can be said to “cause” wildfires is New South Wales’ Gospers Mountain forest fire. The Gospers Mountain fire started from a single ignition point, caused by lightning. Dry forests are more likely to ignite naturally from lightning strikes. The Gospers Mountain fire has now destroyed 860,000 acres - an area twice as large as Hong Kong. According to the Centre for Environmental Risk Management of Brushfires at the University of Wollongong, this is the largest forest fire in Australian’s history, and it was unavoidable; the fire was started naturally, and its rapid growth was a natural consequence of the drought that hit New South Wales particularly severely.

 No filters.  
 Evacuees have flooded Instagram with photos of the red hellscape that is New South Wales.

The Australian Bureau of Meteorology, in its annual State of the Climate report, states that Australia’s climate over the last century has shown an increase in “extreme weather,” with more warm extremes and fewer cool extremes. Projections for Australian climate, based on global trends, predict that Australian temperatures will continue to increase, with more extremely hot days, and that average rainfall will decrease in southern Australia. Based on these trends, it goes on to predict that extreme “fire weather” will continue to increase, and that the fire season will lengthen as climate change continues to promote ideal wildfire conditions.

The Australian government has acknowledged that climate change and global warming is negatively impacting Australia’s environment. The continent is uniquely susceptible to negative impacts due to its geography, already-arid inland, high-pressure systems, strong coastal winds, and unpredictable rainfall. Although techniques for fighting and containing wildfires have improved over the last century, severe wildfires, like those seen in southwestern Australia, are expected to continue to grow in their frequency and intensity as global temperatures rise.

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