Climate change isn’t just about temperature—it is about the basic weather patterns that make up our climate. This includes changes in temperature (warmer & colder), wind, rainfall and storm patterns, frequency and intensity. Weather patterns affect just about everything in our lives: the ability to grow the food we eat, the kinds of diseases and pests that can thrive in our region and affect our health, and the amount of water we have for drinking and landscaping our yards. Weather patterns can also pose challenges to keeping our homes and families safe during extreme weather.
The decade of 2001– 2010 was the hottest decade on record for Greater Yellowstone Region, of which Bozeman is a part, averaging 1.4°F above the 20th century average. Overall, summers are hotter (2.3 °F in the last decade than 20th century summers), snowpacks are smaller, spring snowmelt is occurring earlier, and lower summer river flows are being seen in many major basins. Hotter temperatures and intermittent drought have both been major players in the epidemic of tree-killing mountain pine beetles currently attacking high-elevation forests. Drought and an increasing number of dead trees in turn increase the risk of large, destructive wildfires. Warming rivers and reduced summer streamflow threaten fisheries.
Glaciers are shrinking: the watershed within Grand Teton National Park’s two largest glaciers lost 45 percent of its glacier surface area between 1994 and 2007, and the US Geological Survey predicts that glaciers in Glacier National Park will disappear by 2030-2080.
A warmer and drier climate impacts the reliability of water resources, the frequency and scale of wildfires and insect infestations, and makes planning difficult for farmers, ranchers, and municipal water providers, among others.
Credit: Greater Yellowstone Coalition
Website with Comprehensive information, summaries of current research, and personal accounts of climate change across Montana.
Fishing: Repeated River Closures
When river temperatures are too hot, fish populations become stressed. Low river flows and hot temperatures mean that Montana rivers are closing to fishermen more often these days, in order to preserve healthy fish populations for the future. Take the Big Hole River: it has closed repeatedly to anglers during recent summers, with Fish Wildlife and Parks citing a combination of reduced winter snowpack and warmer-than-normal temperatures. And in the fall of 2016, the Yellowstone River was completely closed to all recreation due to an unprecedented massive fish kill attributed to a parasite never before documented in our region and to high water temperatures/low river flows.
Fires: Larger, More Frequent
Since the mid-1980s, forest fires in western states have become more intense and frequent than older historic fires. The average length of the annual fire season is now 78 days longer than the period between 1970 and 1985. There are four times as many large fires over 1,000 acres, and six times as many acres burned every year. The reasons for this are many, but hotter temperatures, increasing aridity, and an increasing number of dead trees due to beetle kill, all linked to climate change, are probable factors.
Water: Less Predictable Supply
In Montana, we rely on streams and rivers for up to 75% of our yearly water supply. In a state that typically receives less than 18 inches of precipitation each year, this water is important. Whether moisture falls as snow or rain has enormous impacts for late-summer water supply. If snow melts early, there is little water left in streams late in the summer – the hottest time of year, when towns, farmers, ranchers, and even lawns need it most.
Small changes in temperature make a big difference –more days in recent winters have been above freezing, and trends show precipitation has started to fall more frequently as rain.