The Fourth National Climate Assessment (NCA) was released back in November. The NCA is a comprehensive overview of the possible impacts of climate change across the United States over the next hundred years or so, based on the most up-to-date scientific findings. With the “Green New Deal” proposed by the progressive wing of the Democratic Party making headlines, I thought it would be a good time to review our continuously evolving understanding of what climate change might mean for Montana.
The NCA is quite impressive in its scope, and includes chapters for each region of the US. Montana is discussed in the “Northern Great Plains” region along with Wyoming, Nebraska and the Dakotas. For each region, the report chooses several “key messages” that are deemed the most important climate-related impacts for that region. I will briefly review each Northern Great Plains key message in turn.
The top key message discusses—unsurprisingly—water. The majority of streamflow in the region comes from the Missouri River and its tributaries, but because of the aridity of the region and other geographic features, year-to-year streamflow is extremely volatile relative to most other parts of the country. Warming is predicted to only slightly reduce average streamflow but significantly increase its volatility, so storage in the form of groundwater and reservoirs will be increasingly important in the coming decades.
The second key message relates to agriculture. The region has always contended with high levels of year-to-year variability in temperatures and rainfall, but climate change is already pushing these extremes outside of what farmers are used to. Further warming over the century will lead to both more heavy precipitation events along with more heat waves and draughts. Overall, the region will experience warmer, wetter conditions and higher atmospheric concentrations of CO2, which will have mixed effects on agricultural yields, but the higher variability will require significant adaptation.
The third key message discusses recreation. Many outdoor recreational activities are likely to be impacted by climate change, but the two that are currently best understood is fishing and snow sports. Higher stream temperatures are already altering the mix of fish species, and further warming is projected to reduce the value of coldwater fishing by between $25-$66 million per year by the end of the century. For snow sports, the fraction of precipitation that falls as snow is expected to decrease by 25-40% and to fall during a narrower portion of the year, threatening the viability of ski resorts.
Fourth, climate change is expected to impact the region’s energy industry in several ways. Heat waves and high precipitation events will damage the infrastructure used to generate and transmit energy. Yields on biofuels are likely to decrease, and energy demand for cooling in the summer will likely strain capacity.
Finally, the report highlights particular threats to indigenous communities, many of whose way of life is especially reliant on the natural environment. Tribal communities are already reporting significant changes in water cycles, wildlife migration and hibernation patterns, and availability of plant-based foods. Indigenous peoples are particularly vulnerable to the expected changes in streamflows, draughts, and floods discussed above.
An earlier ageconmt post I wrote discussed a paper predicting county-by-county economic impacts expected to result from climate change, which actually predicted positive impacts for Montana and other northern states. This study was generally based on observing past impacts of changes in average temperatures. However, a common theme of the National Climate Assessment is that averages obscure the damages caused by substantially increased volatility in temperatures and other climatic features. The threats to Montana are still likely not as severe as other, hotter parts of the country, but significant planning and adaptation is still likely to be necessary.