Learn About Climate Change

The effects of climate change within the state are felt by and directly impact a wide and diverse range of people including those that make their living off of the land, those that intend to develop the land to live here, and those that use the land for recreational purposes. Climate change has different impacts in different regions of the country. In the West, climate change may lead to:

Changes in natural ecosystems resulting from higher temperatures and possibly intensified winter precipitation
Earlier snowmelt and significant reductions in snowpack stressing some reservoir systems
Decreased yields of crops that are already near climate thresholds
Increased stress on groundwater systems leading to decreased recharge
Higher summer heat; reduced winter cold stress
Increased wildfire potential

Montana: Trout and Drought
How is climate change affecting Montana? Warmer springs are making snow melt sooner, and early snowmelt leaves rivers low by summer's end. A look at what it all means for anglers, farmers and other Montanans, and how they are responding.

Montana: Trout and Drought HD from Climate Central on Vimeo.

The following information was derived from the US EPA publication entitled, "Climate Change and Montana". For the complete report, please visit: http://yosemite.epa.gov/oar/GlobalWarming.nsf.pdf.

Impacts for Montana
Over the last century, the average temperature in Helena, Montana, has increased 1.3°F, and precipitation has decreased by up to 20% in many parts of the state.

Over the next century, climate in Montana may change even more. For example, based on projections made by the Intergovernmental Panel on Climate Change and results from the United Kingdom Hadley Centre's climate model (HadCM2), a model that accounts for both greenhouse gases and aerosols, by 2100, temperatures in Montana could increase by about 4°F in spring and summer (with a range of 1-8°F) and 5°F in fall and winter (with a range of 2-10°F). Precipitation is estimated to increase by roughly 10% in all seasons except winter, when the range of estimated increase is 15-40%. The amount of precipitation on extreme wet or snowy days in winter is likely to increase. The frequency of extreme hot days in summer would increase because of the general warming trend. Although it is not clear how severe storms would change, an increase in the frequency and intensity of winter storms is possible.

Human Health
Higher temperatures and increased frequency of heat waves may increase the number of heat-related deaths and the incidence of heat-related illnesses. Montana, with its irregular, intense heat waves, could be susceptible. The elderly, particularly those living alone, are at greatest risk.

Warming and other climate changes may expand the habitat and infectivity of disease-carrying insects, thus increasing the potential for transmission of diseases. A recent study has concluded that a 5-9°F temperature increase would cause a significant northern shift in Western equine encephalitis outbreaks. Mosquitos capable of transmitting this disease already are present in Montana. If Montana's climate becomes warmer and wetter, mosquito populations could increase and conditions may become more favorable for disease transmission.

Water Resources
Water resources are affected by changes in precipitation as well as by temperature, humidity, wind, and sunshine. Changes in streamflow tend to magnify changes in precipitation. Water resources in drier climates tend to be more sensitive to climate changes. Because evaporation is likely to increase with warmer climate, it could result in lower river flow and lower lake levels, particularly in the summer. If streamflow and lake levels drop, groundwater also could be reduced. In addition, more intense precipitation could increase flooding.

Western Montana drains into the Columbia River system, and most of the remaining areas of the state drain to the east into the Missouri River or its major tributary, the Yellowstone River. Winter snow accumulation and spring melt are key processes that affect the runoff of all rivers within the state. A warmer climate would lead to earlier spring snowmelt, resulting in higher streamflows in winter and spring and lower streamflows in summer and fall. Earlier spring snowmelt could reduce the performance of the reservoir system in western Montana, thus reducing summer and fall runoff, which is critical for power generation, fisheries protection, recreation, and other uses. Increased rainfall could mitigate some of these effects, but it also could lead to increased flooding.

Agriculture
The mix of crop and livestock production in a state is influenced by climatic conditions and water availability. As climate warms, production patterns could shift northward. Increases in climate variability could make adaptation by farmers more difficult.

Warmer climates and less soil moisture due to increased evaporation may increase the need for irrigation. However, these same conditions could decrease water supplies, which also may be needed by natural ecosystems, urban populations, industry, and other sectors.

Understandably, most studies have not fully accounted for changes in climate variability, water availability, and imperfect responses by farmers to changing climate. Including these factors could change modeling results substantially. Analyses that assume changes in average climate and effective adaptation by farmers suggest that aggregate U.S. food production would not be harmed, although there may be significant regional changes.

In Montana, agriculture is a $1.8 billion annual industry, one-half of which comes from livestock, mainly cattle. Just over 20% of the crop acreage is irrigated. The major crops in the state are wheat, barley, and hay. In a warmer climate wheat yields could increase by more than a third, and changes in barley and hay yields could vary between -8% and +13%, depending on whether irrigation is used, leading to changes in acres farmed and production.

For example, barley yields could rise while production falls because of a decrease in barley acres farmed. An increased dependence on irrigation is possible, depending on the relative balance between rainfall and increased evaporation.

Forests
Trees and forests are adapted to specific climate conditions, and as climate warms, forests will change. These changes could include changes in species, geographic range, and health and productivity. If conditions also become drier, the current range and density of forests could be reduced and replaced by grasslands and pasture. Even a warmer and wetter climate could lead to changes; trees that are better adapted to these conditions, such as fir and spruce, would thrive. Under these conditions, forests could become more dense. These changes could occur during the lifetimes of today's children, particularly if change is accelerated by other stresses such as fire, pests, and diseases.

Some of these stresses would themselves be worsened by a warmer and drier climate. With changes in climate, the extent of forested areas in Montana may change little or could decline by as much as 15-30%. The uncertainties depend on many factors, including whether soils become drier and, if so, how much drier. Hotter, drier weather could increase the frequency and intensity of wildfires, threatening both property and forests. Drier conditions could reduce the range and health of lodgepole and Douglas fir forests, and increase their susceptibility to fire. With increases in rainfall, however, these effects could be less severe. Grass and rangeland could expand into previously forested areas along the eastern slope of the Rocky Mountains and into some of the western valleys. Milder winters could increase the likelihood of insect outbreaks and of subsequent wildfires in the dead fuel left after such an outbreak. These changes would significantly affect the character of Montana forests and the activities that depend on them.

Ecosystems
Ecosystems in Montana are diverse, ranging from grasslands and deserts to mountain shrublands, forests, meadows, and alpine tundra. They also include numerous wetlands and streams.

Because of elevation changes and human land use, many habitats are fragmented and restricted in area. Changes in temperature and precipitation caused by climate change could affect the location and productivity of these ecosystems.

Warming and changes in precipitation could affect alpine areas, causing tree lines to rise by roughly 350 feet for every degree Fahrenheit of warming. Mountain ecosystems such as those found in Glacier National Park could shift upslope, reducing habitat for many subalpine species. Alpine animals and species, many of which are unique to the region, could disappear from the highest elevations. Mountain glaciers such as those found in Glacier National Park are expected to shrink, possibly leading to higher stream temperatures and decreased runoff. This would adversely affect aquatic biota, including trout species. Changes in rainfall and snowfall also could alter streamflows and wetlands, affecting wildlife and possibly accelerating the invasion of non-native plants into streamside habitats. Aquatic species that are sensitive to water temperature could be affected adversely by climate change. Brown trout and rainbow trout could lose habitat.

Glacier National Park
Glacier National Park is located in a pristine mountainous area in northwest Montana. The park provides habitat for an abundance of wildlife, including the most dense population of grizzly bears (an endangered species) in the United States. Other endangered animal species found in the park include the bald eagle and the gray wolf. Over 1,400 different plants live in Glacier Park, 28 of which are found nowhere else in Montana.

Climate change could have a serious impact on Glacier National Park. The park has approximately 50 glaciers today, down from an estimated 150 glaciers in 1850. The recession of Sperry Glacier illustrates the impact of recent warming temperatures in the park. If these warming trends continue, it is estimated that no glaciers will be found in the park by 2030. Without glaciers, stream temperatures are expected to rise, which could affect aquatic ecosystems in the park, including trout species. Climate change also could affect the types of trees found in the forests. Lodgepole pine and western cedar forests could yield to forests dominated by spruce and western hemlock. Six rare alpine plants that are at the southern border of their geographic range would be especially vulnerable to climate change.