Climate Corner
Montana Climate Matters: takeaways on climate change in Montana
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Today’s Montana Climate Matters column is a reality check. Like the rest of the planet, Montana’s climate is warming, and warming will continue as long as we increase levels of carbon dioxide and other greenhouse gases in the atmosphere. Montana has experienced few climate-driven weather disasters in comparison to other parts of the world, but we’re unlikely to escape them in the future. A recent report by the Intergovernmental Panel on Climate Change (IPCC) states that global temperatures are certain to rise over the next 20 years, but the magnitude and rate of climate change and the associated risks depend strongly on our near-term actions. Adverse impacts and related losses and damages to Montana escalate with every increment of global warming.
Montana is experiencing climate change in many ways:
1. Annual average temperatures, including daily minimums, maximums, and averages have risen across Montana between 1900 and 2015, and especially since 1990. Ten of the warmest years on record have occurred since 2000, with 2015 and 1934 tied for the hottest years.
2. Montana’s snowpack has declined since the 1930s in the mountains west and east of the Continental Divide. Between 1955 and 2022, snowpack losses have ranged between 20-80%, and the decline is most pronounced since 1980.
3. Historical observations show a shift toward earlier snowmelt and an earlier peak in spring runoff in Montana. Early, rapid melting has led to major spring floods in many parts of the state, including the 1-in-500-year flood in northern Yellowstone in 2022.
4. Multi-year and decadal droughts are a natural feature of Montana’s climate, but rising temperatures have exacerbated drought when and where it has occurred. Most counties have been in some state of drought since 2000.
5. In the future, Montana temperatures are projected to rise in all geographic locations, seasons, and under all currently projected greenhouse gas emission scenarios through the 21st century. Montana is expected to warm 4-6oF by 2050 and as much as 10-12oF by the end of the century. Climate models indicate 5-35 additional days of temperatures over 90oF by mid-century, with eastern and southern Montana getting more extreme-heat days than other parts of the state.
6. Precipitation in Montana is expected to increase slightly in the coming decades, with the greatest increases in winter, spring, and fall. Precipitation is projected to decrease in summer. This shift in the timing of precipitation means more precipitation falls as rain than snow.
7. Rising temperatures through the 21st century will reduce snowpack below historical levels, particularly at mid and low elevations. By 2100, snowpack will be negligible below 10,000 feet.
8. Snowpack will continue to melt earlier in the year in coming decades as temperatures increase. Earlier onset of spring runoff and more rain-on-snow events will increase the likelihood of spring flooding and reduce late-summer water availability in snow-dominated watersheds.
9. Changes in temperature, snowpack, streamflow dynamics, and groundwater resources will have far-reaching ecological consequences, including increasing tree mortality, wildfires, and insect epidemics, as well as altering wildlife behavior and distribution. Although the mid- to late 21st century seems far off, it is important to remember that our children and grandchildren will experience the brunt of these effects.
10. Some climate changes may be beneficial. For example, longer growing seasons will encourage development of new crops and livestock breeds. However, most climate changes pose challenges, including how to deal with less public and private water supplies, unreliable winter and summer recreational opportunities, shifts in energy demand, and more climate-driven weather surprises.
The time for action is now.
The next column will address climate change and its impacts on Montana’s agriculture.
Cathy Whitlock is Regents Professor Emerita of Earth Science at Montana State University and lead author of the 2017 Montana Climate Assessment.
