As cooler temperatures and precipitation finally bring relief to smoke-weary Montanans, the unusual nature of summer 2017 is coming into focus and the influence of climate change is impossible to ignore.
Extreme weather has been the dominant story throughout the country this summer as hurricanes have ravaged the southeastern United States and wildfires have wreaked havoc in the West. A simple Google search will yield hundreds of stories about the impacts of these events, but, unfortunately, very few mention climate change as a contributing factor.
Collectively, we have over 65 years of experience studying western climate and forest systems, and we are among the authors of the forthcoming Montana Climate Assessment, a report focusing on climate trends and their consequences for Montana’s water, forests and agriculture. We invite everyone to consult the report, which will be available after Sept. 20 at www.montanaclimate.org.
Was this fire season remarkable?
2017 is already a record-breaking wildfire season in regions of Montana, and the fingerprints of climate are easy to spot. In many ways, what we’ve seen this year is exactly what we’ve come to expect, but in other ways, it’s even more worrisome.
Large fires have increased in the last three decades, and this year will be one of the worst, especially in Montana, where wildfires have burned over 1 million acres (www.nifc.gov). The persistence of some of these fires has been unusual, choking western Montana with health-threatening smoke for weeks.
What role did climate change play?
Climate has played a big role. While it’s impossible to tie any one weather event or wildfire directly to climate change, we can say with certainty that increases in temperature in the last decades have set the stage for drier conditions and more fires. In a given year, warmer weather and less precipitation dries out fuel loads and creates conditions for rapid fire spread. Fire records dating back decades to millennia show a clear link between warmer temperatures, lower precipitation and an increase in the number of fires and acres burned. This situation is precisely what we expect to see from climate change.
Montana has been on a steady warming trend for decades, up over 3°F since 1950, and all projections are that it will continue. This summer was the second warmest on record since 1950 at 4 degrees F above average, and the persistent high temperatures coupled with the record lowest rainfall in July and August led to extreme drought by midsummer.
What can we expect in the future?
These extreme weather events weren’t unforeseen and are not without a systemic cause. As the buildup of greenhouse gases in our atmosphere intensifies, our overall climate and weather patterns will continue to change. We can expect additional warming with less precipitation in the summer. Over the next century, extreme heat days (above 90°F) are projected to increase by an additional 5-35 days. As a result of greater drought, forest fires will likely increase in size, frequency and possibly severity.
Factors contributing to wildfire are complicated, but they involve both forest management and climate conditions. From 2006-2015, 95 percent of wildfires were suppressed at a cost of $13 billion. This level of expenditure is not sustainable and the burden on state and local resources is enormous. New adaptive approaches are needed to manage forest fuel loads and reduce wildfire risk and costs (e.g., fuel treatments, especially on private land, and fire-adapted planning and land use) while also recognizing that fire is part of healthy forests. We must consider policies that will curb greenhouse gas emissions, which are the main driver in climate change.
Together, we can and must develop plans to increase resilience, mitigate expected impacts and address the known causes of climate change.