The world's leading and largest scientific body on climate change—the Intergovernmental Panel on Climate Change (IPCC)—projects temperature increases in the Western U.S., including Montana, for a wide range of greenhouse gas emission scenarios. The size of the projected increases depends on the amount of emissions assumed in each scenario, from low to high. See the IPCC's recent report from Working Group I, “The Physical Science Basis,” especially Figure 10.8 on p. 766 of the printed document.

Climate Central scientists have converted data from climate models into animations that show how spring temperatures in Montana are projected to rise as the century proceeds. Specifically, the animations show that areas where the average March temperature remains above freezing are likely to expand (see Interactive Climate Forecast).

A recent report (Healing Troubled Waters: Preparing Trout and Salmon Habitat for a Changing Climate) by the nonprofit organization Trout Unlimited states that “[l]osses of western trout populations may exceed 60% in certain regions,” citing several scientific reports as supporting information, including: Keleher and Rahel predict considerable reductions in the amount of suitable trout habitat in the Rocky Mountain region, based on predictions of increasing average air temperatures for July; Rahel and colleagues estimated reductions in trout habitat in Wyoming due to a range of possible temperature increases. For general information on this subject, see also a recent report (Seasons' End: Global Warming's Threat to Hunting and Fishing) by the Seasons' End organization; the report was published by the Bipartisan Policy Center.

See the U.S. Fish and Wildlife Service's 2006 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation. For 2006, the estimated expenditures for state residents and visitors from out-of-state totaled about $330 million (see the Montana-specific data).

In general, movement of soil and other particles from the land into waterways (“sedimentation”) can make stream water cloudier and can add to existing sediments on stream and lake bottoms, affecting fish and other aquatic life. For a comprehensive discussion of this topic, see a paper by Curry and colleagues in the Journal of the North American Benthological Society.

The discussion around summer drought season, just below, addresses the issue of reduced stream flow.

Drought refers here to prolonged periods with reduced stream flows (but not necessarily reduced precipitation). In a 2004 paper in the journal Climatic Change, Stewart and colleagues showed that, since the late 1940s, there has been a trend in river flows for much of the Western U.S. that is consistent with lower stream flows in late-summer, which means the dry season begins earlier and thus lasts longer.

For rivers with flows dominated by melting snow in their headwaters—the norm in many parts of the Western U.S.—a shift toward earlier snowmelt will generally lead to periods during the late summer with comparatively lower streamflows. Using a network of stream gages, the U.S. Geological Survey constantly measures the quantity of water flowing down many rivers across the country, enabling estimates of annual flow volume. A common way to characterize the timing of a river's flow is to look at the date when half of the river's annual flow volume has occurred. In their 2004 paper, Stewart and colleagues showed that this date has been coming earlier in the year for much of the Western U.S. (specifically, they tracked this date each year from 1948 to 2000 for a large number of streams and rivers).

Current research in Professor Steve Running's lab at the University of Montana is showing that streamflows in seven Montana rivers have late-summer levels that have dropped 20 to 30% since 1950. Their tentative interpretation is that changes in both climate and withdrawal of water for irrigation are driving these decreases in in-stream flow. The data underpinning this research come from the U.S. Geological Survey and can be accessed from the National Water Information System website.

In addition, trends in other indices that are related both to climate and river flows in the Western U.S. are consistent with earlier river flows caused by warming (for example, less snow pack leads to less melt water to sustain stream levels¹).

Footnotes

1. See Science & Sources under KEY POINT, "Montana’s upward March temperature trend is consistent with global warming…" at timecode 2:29. ↑

The term drought can be used to mean several different things, though these uses are usually closely related. As described by the Intergovernmental Panel on Climate Change in its latest (2007) assessment (pp. 186-87, Working Group II Report):

The term drought may refer to meteorological drought (precipitation well below average), hydrological drought (low river flows and water levels in rivers, lakes and groundwater), agricultural drought (low soil moisture), and environmental drought (a combination of the above). The socio-economic impacts of droughts may arise from the interaction between natural conditions and human factors, such as changes in land use and land cover, water demand and use. Excessive water withdrawals can exacerbate the impact of drought.

A tail water describes a particular type of fishery, which is dependent on relatively cool water being released from the deep, cool portion of an upstream reservoir. Tail-water fisheries may be partially insulated from effects of climate warming (see a paper by Sinokrot and colleagues in the journal Climatic Change that discusses the potential for climate change to affect tail-water fisheries).

See just below.

The Montana State Climate Office has compiled data on a trend toward less snowfall in Montana since 1950 (see slide 5 on their site).

See discussion² and the record of Montana's increasing March average temperatures³.

Another study (see discussion of paper by Barnett and colleagues⁴) has shown that trends towards earlier snowmelt and a lower proportion of precipitation as snow are seen in the western US generally, including parts of Montana, and that these trends seem to be due to human-caused climate change.

Footnotes

2. See discussion at timecode 1:00. ↑
3. See discussion under Key Point "Montana's increasing March average temperatures…" beneath timecode 2:29. ↑
4. See Science & Sources under Key Point, "Montana’s upward March temperature trend…" beneath timecode 2:29. ↑

Steve Running is Regents Professor in the Department of Ecosystem and Conservation Sciences and Director of the Numerical Terradynamic Simulation Group at the University of Montana. Running is also host of the Montana State Climate Office.

The 78°F threshold for trout mortality is a commonly cited benchmark that was first discussed in a National Academy of Sciences report in 1972. An EPA report from 2001 by McCullough and colleagues is a key resource discussing the temperature threshold for fish in the trout family (salmonids). An EPA report from 1999 provides additional summary information on temperature limits for trout and other species. See also a 1995 paper by Eaton and colleagues in the journal Fisheries that discusses the topic in detail.

This range is based on records from five weather stations across the state (see The Montana State Climate Office study, slide 2). A separate analysis based on statewide data from almost 700 stations suggests a similar overall average warming (7.6°F from 1950 to 2007).

The Intergovernmental Panel on Climate Change's recent report (Working Group I, “The Physical Science Basis”) includes a breakdown of how natural and human influences have contributed to the rise in temperature from 1906 to 2005 over the Earth's continents (see FAQ 9.2, Figure 1, which is on p. 703 of the printed document available at the link above). In this analysis, climate models that include both natural and human factors accurately reproduce the observed temperature increases over the past 100 years, whereas those that include only natural factors do not—strongly suggesting a human imprint on warming generally.

More local to Montana, a 2008 article in the journal Science by Barnett and colleagues shows that trends in several parameters (river flow, winter air temperature, and snow pack) in the Western U.S. are inconsistent with any known explanation other than human-induced climate change. A paper soon to be released in the Journal of Climate by Bonfils and colleagues shows that trends in daily minimum and maximum temperatures, frost days, and days above 32°F in the Western U.S. are too rapid to be explained by any known phenomenon other than human-enhanced greenhouse warming.

Climate Central scientists have converted data from climate models into animations that show how spring temperatures in Montana are projected to rise as the century proceeds. Specifically, the animations show that areas where the average March temperature remains above freezing are likely to expand (See Montana temperature animation).

See discussion above⁴. Connecting all the pieces, warmer air temperatures in March mean that snow in the mountains begins melting earlier in the year. This translates to less water from melting snow toward the end of the summer, all else being equal, because the snowpack is depleted earlier.

Footnotes

4. See discussion at timecode 1:00. ↑

See just below.

In a 2006 paper in the journal Science, Westerling and colleagues showed that the numbers of large forest wildfires, acres burned by such fires, and the length of the fire season have increased markedly in the Western US since the mid-1980s. These changes in wildfire patterns have been shown to be closely associated with climate trends, particularly increased spring and summer temperatures, and earlier spring snow-melt (see also a summary of their findings by Running in the same issue). These are the same climate trends that are threatening trout populations.

An additional factor behind the trend in wildfire size specifically is decades of fire suppression, which has led to build up of brush and other fuel that would historically have been kept in check by frequent fires (see a 2007 paper by USDA Forest Service researchers Donovan and Brown). Thus, when fires do occur, they generally are larger because of the accumulation of fuel. 

A 2008 paper by Raffa and colleagues in the journal Bioscience presents data from several U.S. and Canadian sources that document an increase in mountain pine beetles in a region spanning the western part of both countries that includes Montana.

See a 2008 USDA Forest Service publication that describes in detail the recent situation with bark beetle infestations in Montana and neighboring states. Insect infestations are typically driven by the condition of the host trees, which can become more susceptible to infestations during drought conditions, although there may be a delay of years before insect outbreaks are observed. 

The Canadian Forest Service has a comprehensive publication on the biology of the mountain pine beetle. In general, winter low temperature at or below minus 40°F or high winds during the dispersal of the beetle's larvae is needed to reduce their spread (see page on Canadian Forest Service site).

A 2008 study by Kurz and colleagues in the journal Nature showed that large pine beetle outbreaks—like the current one in British Columbia—can turn an area that was accumulating carbon through forest growth (potentially helping to offset human-caused emissions of carbon dioxide) into an area that is releasing significant amounts of carbon into the atmosphere (principally as carbon dioxide) as dead trees decay.

A 2007 paper by Cook and colleagues in the journal Earth-Science Reviews provides a detailed analysis of the drought history in the Western U.S. A website related to the study provides more information as well as an animation that helps to visualize the regularity of droughts over recent centuries. This paper follows a 2004 paper by Cook and colleagues in the journal Science documenting the long-term drought record in the Western U.S. since medieval times.

In an interview with Climate Central in September 2008, Roger Pielke Sr. stated “…we expect that the droughts are more serious today because of the growth of the population and of the demands for water…so we are more vulnerable to drought in Colorado and the Western United States than we would have been with the same weather conditions 50 years ago or more.” But, as he explains in his next statement in the video (below), Dr. Pielke Sr. feels action is needed regardless of the cause.

A 2008 paper in the journal Science by Barnett and colleagues linked human-caused climate change with changes to date in the hydrology of the Western U.S., including reduced snow packs, increased winter air temperatures, and reduced summertime river flows. Looking into the future, a 2008 paper in the journal Geophysical Research Letters by Rauscher and colleagues shows how rising temperatures from greenhouse gas warming will likely lead to snowpack melting earlier, ultimately leading to lower late-summer river levels⁵.

Further, in a 2007 paper in the journal Science, Seager and colleagues describe model results that suggest the Southwestern U.S. will transition to a more arid climate in the years to come due to human-caused climate warming.

Footnotes

5. See Science & Sources section supporting discussion at timecode 1:00. ↑

A 2005 U.S. Geological Survey report (Water availability for the Western United States: Key scientific challenges) is a comprehensive assessment of water issues in the Western U.S. It includes the following:

A steady demographic shift is occurring in the United States. According to the 2000 U.S. Census, about one-third or 91.5 million of the 281 million people in the United States now reside in the 17 Western States…. These Western States accounted for 50 percent of the U.S. population growth from 1990 to 2000…and 7 of the 10 fastest growing States in the Nation are in the West….

See above.

In an interview with Climate Central in September 2008, Roger Pielke Sr. talked about what steps should be taken in the Western U.S., including: “What we need to do is consider ways to transport water over large distances so one area that's dry can benefit by another area that is wet. We need to design water storage approaches that are more effective at accumulating water for long time periods that are environmentally sensitive and provide some buffer to very dry periods.”

The 2006 publication Water Rights in Montana, posted on the State's website, discusses Montana water issues at length, including the following:

Montana waters, in all their varied forms and locations, belong to the state…water rights holders do not own the water itself…they possess a right to use the water, within state guidelines…. Water rights in Montana are guided by the prior appropriation doctrine, that is, first in time is first in right. A person's right to use a specific quantity of water depends on when the use of water began. The first person to use water from a source established the first right; the second person could establish a right to the water that was left, and so on. During dry years, the person with the first right has the first chance to use the available water to fulfill that right. The holder of the second right has the next chance. Water users are limited to the amount of water that can be beneficially used. In Montana, the term “beneficial use” means, generally, a use of water for the benefit of the appropriator, other persons, or the public, including but not limited to agricultural (including stock water), domestic, fish and wildlife, industrial, irrigation, mining, municipal, power, and recreational uses.

A similar quotation, "Whiskey's for drinking, water's for fighting over," is often attributed to Mark Twain.

In an interview with Climate Central in September 2008, Walt Sales also spoke about why he got involved with The Association of Gallatin Agricultural Irrigators. He said the association, of which he serves as president, has been involved in water rights issues at the government level, and has been working closely with such conservation organizations as Trout Unlimited and Montana Fish, Wildlife and Parks. "We are starting to understand each other and at least know the issues and have a relationship," he said in the interview, "that I think is turning into one that even though we don't agree on issues 100% we are starting to understand each other's value points and finding a common ground. We both want good, clean available water in the river, so we are starting to come together on that."

Montana's Department of Agriculture reports that cash receipts for the agricultural sector exceed $2.4 billion, whereas the USDA's Economic Research Service puts the value at just less than $2.4 billion in 2007 (data can be downloaded from this link).

This total income comes from agriculture on both irrigated and non-irrigated land. The 2002 Census of Agriculture estimated that 8.5% of Montana's cropland was irrigated. However, farmers generally grow crops of much higher value on irrigated cropland compared to non-irrigated areas.

About 29% of Montana's land area is federally owned, according to the USDA's Natural Resources Conservation Service. Montana's Department of Agriculture reports that more than 90% of Montana's private land is devoted to agricultural production.

See above.

Based on data from the Department of Energy's Energy Information Administration, as of January 1, 2007, Montana's estimated “demonstrated reserve base” (DRB) of coal was 119 billion tons, 24% of the total estimated U.S. DRB. Some portion of U.S. DRBs will most likely not be mined due to technological, economic, environmental, or other constraints.

According to current estimates, one to five gallons of water will be required per gallon of liquid fuel produced (see document on Western Governors' Association website having to do with liquid fuels from coal). The actual figures will depend upon technological refinements.

For a technical description of how coal can be converted to liquid fuels, see this paper co-authored by Climate Central scientists Kreutz and Larson and others. The following brief synopsis of the technology is excerpted and summarized from their paper:

Recent oil price increases have led to considerable interest in making synthetic fuels from coal—so called coal-to-liquid (CTL) fuels—in light of coal's relatively low prices and the abundance of coal both in the US and in other world regions that are not politically volatile. Much of this attention has been focused on Fischer-Tropsch liquids (FTL). Coal can do much to improve energy security if it is used to make FTLs. Moreover, the synthetic fuels provided would be cleaner than the crude oil products like diesel fuel that would be displaced (having essentially zero sulfur and other contaminants and ultralow aromatic content). Also, for FTL production via modern entrained flow gasifiers, the air pollutant emissions from the plants would be extremely low.

But synthetic fuels made from coal without capture and storage of by-product carbon dioxide (CO2) would result in net greenhouse gas (GHG) emissions about double those from petroleum fuels. And even with carbon capture and storage (CCS), the net GHG emission rate would be no less than that for the crude oil products displaced.

Based on 1 to 5 gallons of water required per gallon of fuel produced, a plant producing 50,000 barrels of diesel (and other fuels) per day—the initial production target for the new plant planned at the Crow Reservation (the “Many Stars Project”)—the annual water use would be from 1740 to 8680 acre-feet of water per year (note: full projected capacity for the Many Stars Project is 125,000 barrels per day). Estimates from the University of Montana's Department of Land Resources and Environmental Sciences are that irrigated alfalfa requires from 18 to 36 inches of water per year; 2000 acres of irrigated alfalfa would require from 3000 to 6000 acre-feet of irrigation water.

See discussion above (Kreutz/Larson PDF paper).

See Montana Wind Energy.