Local Impacts

Climate change is manifesting in multiple, interpenetrating ways depending upon characteristics of the regional subclimate.

Here we present a series of articles drawn from our Science Primer that was published in the Ravalli Republic newspaper:

Ravalli County Already Experiencing Climate Change - by Kit Tilly and Hillery Daily

Increasing In-Migration: An Effect of Climate Change on the Bitterroot Valley - by Kit Tilly and Hillery Daily

Below we present additional essays from our local scientists and specialists about expected impacts of climate change to the Bitterroot Valley. If you have comments, questions or ideas contact the Chair of our Science Committee Kit Tilley

Climate Change Impacts on Our Health, by Kit Tilly, PhD

Climate Change and Montana Land by Hillery Daily, ND

Climate Change and Montana Water by Becky Miller

Expected Climate Change Effects on Arthropods: Ticks, Mountain Pine Beetles, Honeybees by Kit Tilly, PhD

Suggestions for Reducing Your Carbon Footprint by Bill Salterburg

Climate Change Impacts on Our Health

Climate change is likely to have profound impacts on human health here in the Bitterroot Valley. A recent draft special report of the Montana Climate Assessment (MCA), entitled Climate Change and Human Health in Montana has just been released. This report summarizes the climate predictions of the initial MCA, which include the following:

• Precipitation in western Montana will have a higher proportion of rain to snow, resulting in earlier run-off.
• There will be an increased probability of rain-on-snow events, which often lead to flooding.
• Late summer droughts, plus hotter drier summers, will increase the likelihood of catastrophic wildfires, with associated smoke and displacement of people and animals.

The report then goes on to detail likely health consequences of these changes in our local climate.

Among the impacts of heat and wildfire smoke on health are increases in severity of asthma and other respiratory ailments, along with exacerbating other cardiopulmonary illnesses. Heat stroke and heat stress, especially for the elderly and other vulnerable populations, such as those who lack the ability to cool their homes, will be more common. Earlier runoff and floods could cause contamination of water supplies, leading to gastrointestinal illness. Flood conditions will also affect mosquito populations, and could increase the likelihood of mosquito-borne diseases, like West Nile virus. Summer droughts and higher temperatures will have a negative impact on agriculture, affecting the home gardens that many depend on for supplemental food and income, but also damaging crop yields for local small farmers and ranchers. Drinking water shortages are possible, along with short supply of irrigation and stock water. All of these potential stresses, combined with worldwide disease outbreaks, like the current Covid-19 pandemic, could lead to increased anxiety and depression.

The authors recommend several actions to prepare for the impacts of climate change on human health. These include improving monitoring of our changing climate, improved public health capacity, and collaboration among local and statewide public and private health providers. I would add that Montanans have always looked out for each other, including across political divides, and that this altruistic tendency must be perpetuated. We must keep reaching out to our neighbors, especially if climate change puts additional burdens on our health care system.

Climate Change and Montana Land

Hillery Daily

By Hillery Daily, ND

Montana’s climate and climate trends have been changing right along with the entire planet’s climate.  These new patterns are and will continue to affect our water, forests and land.  So far, the average temperature has risen 2-3 degrees F which is about 1 degree higher than the increase worldwide.  The higher rate of temperature increase in Montana is predicted to continue throughout the coming century.

Also, precipitation in Montana has decreased in the winter and increased during the spring, and this pattern is predicted to continue.  The reduced snow and increased rain in winter will lead to drier summers, as the decreasing snowpack melts earlier.  There will be more dry days in a row (remember the record 47 days without significant rain in the summer of 2017?) and more additional extreme heat days, which are those over 90 degrees F.  Surprisingly, Hamilton is unique in that the state-wide climate trends don’t appear to be happening here.  In Montana, except for the Hamilton area, nighttime temperatures are warming.

Overall, the most disruptive climate changes in Montana will be warmer/hotter days and nights, dryer summers, especially late summer, with decreased water in watersheds and increased drought and wildfires.  In fact, there appears to be a nearly 20 year “mega-drought” in the western US, according to a very recent study in the journal, Science.  This drought, which is thought to be as bad or worse than any in the past 1,200 years, is impacting 9 states including Montana.  Scientists say about half of the drought can be blamed on global warming.   According to the study, the 20th century was the wettest century during this 1,200 year record, giving “us an overly optimistic view of how much water is potentially available”.  Science, 2020; 368 (6488): 314 DOI:

For forests, these changes mean increased likelihood of fires (releasing the tree-stored carbon into the atmosphere).  According to Bruce Maxwell, a lead author of the 2017 Montana Climate Assessment, forest management does not appear to decrease forest fires. The increase in the number of drier and hotter days is causing more intense wildfires.   Despite the threat of fire, the best situation is to keep forested land intact.  Management serves best at the urban-forest interface.

For agriculture and gardening, although growing seasons may be longer, water will be scarce in late summer and early fall.

There is much that we can do.

  • Advocate for not only keeping our forests intact, but plant more trees. The shade from trees is good for all of life, including the trees themselves, since there will be less evaporation under a tree canopy.  Tree communities form underground networks that benefit the soil and all plants.
  • Keep grassy areas, marshes, and streams protected from incursion by domestic animals and humans.
  • Plant gardens with regenerative, no or low till methods.
  • Support local farms, dairies, and ranches by purchasing locally. Consider a community supported agriculture share if you don’t garden and/or support farmer’s markets.
  • Plant native plants/flowers.
  • Minimize the use of pesticides and herbicides for the health of all living organisms, including the soil microbiota.
  • Water lawns and plants in the early morning or late evening or use other water-conserving methods such as mulching to reduce evaporation and water waste.

Climate Change and Montana Water

By Becky Miller

Water is vital to life. In Montana, we depend on water for our natural ecosystems, agricultural irrigation, hydroelectric power, and domestic and industrial uses. Increasing levels of greenhouse gas emissions produced from fossil fuels are contributing to the rapid rise in our average global temperatures. A warming climate will influence Montana’s snowpack, streamflow dynamics, and ground water resources.

The vast majority of Montana’s water is derived from within our state boundaries, entering as precipitation. In western Montana, the majority of our annual precipitation falls as snow in the winters. For our central and eastern regions, it is rain in the springs and summers. Western Montana is known as the Crown of the Continent, because the snowpack in our mountains forms the headwater streams that supply water to the Columbia, Missouri-Mississippi, and Saskatchewan rivers, which are all significant rivers draining three of North America’s largest watersheds. Since the 1950s, low elevations west of the Continental Divide that are exposed to warmer Pacific air masses have been experiencing an increase in rain instead of snow, resulting in reduced snowpack volume and a shorter duration runoff that causes reduced streamflow in the late summer and early fall. Since the 1980s, the Rocky Mountains have been experiencing warmer spring temperatures resulting in snowpack declines at mid and low elevations. Montana stores a large amount of snowpack at mid and low elevations, making this part of the snowpack most vulnerable to increasing spring temperatures and further snowpack decline.

Streamflow is influenced by rainfall, snowmelt runoff, groundwater discharge, and glacial runoff. Annual streamflow determines the volume of water available to us for the year and is important in groundwater recharge and filling reservoirs and lakes, which greatly impacts our hydroelectric power generation, agricultural production, wildlife habitats, and outdoor recreations. Snowmelt and the timing of runoff are dependent on temperature, elevation, and precipitation. Montana has been experiencing rising winter and spring temperatures since the 1950s and western Montana has had a rapid decline in the annual number of days below freezing since the 1980s. Warmer temperatures will cause an increase in snowmelt runoff in winter and spring and will reduce streamflow in late summer and fall.

Increasing air temperatures and declining summer streamflow are warming our rivers and streams. Montana’s rivers and streams provide habitat for more temperature sensitive species such as bull trout, cutthroat trout, and pearlshell mussels. The warming water has forced populations of brown trout and bull trout to shift upstream in search of cooler habitats. Historically colder sections of rivers are warming and supporting fishes like the smallmouth bass and the rainbow trout. The rainbow trout have expanded into the range of the cutthroat trout and have begun to mate with the cutthroat trout producing hybrids, further impacting their survival as a species (http://fieldguide.mt.gov/speciesDetail.aspx?elcode=AFCHA02088).

A warming climate has led to an increase in average temperature throughout our state, which is most evident in our decreasing glaciers in Glacier National Park (Repeat Photography Project by the United States Geological Survey: nps.gov/glac/learn/nature/melting-glaciers.htm). The first survey of Glacier National Park in the 1850s found close to 150 glaciers; presently only 25 remain. The majority of the glacial melt has been occurring since the 1980s. Increasing temperatures have caused glacial retreat by reducing the period of glacial accumulation and extending the period of summer ice melting. Scientists are predicting that the vast majority of the glacial ice will disappear within the next 20 years.
Our warming climate is the leading cause of our rapidly melting glaciers. Higher temperatures during winter and spring are causing snowpack decline and earlier runoff, leading to lower summer and fall stream levels, which will be more sensitive to warming from the increasing air temperatures. Montana’s rivers and streams may warm too rapidly for our aquatic species to adapt, which will threaten their existence. Increasing rains during our springs will temporarily offset our declining snowpack, but eventually we will begin to experience water shortages. Montana’s snowpack is our natural reservoir, melting into streams at a more consistent rate, on which we and our natural ecosystems greatly depend. (2017 Montana Climate Assessment)

Expected Climate change effects on arthropods:
Ticks, mountain pine beetles, honeybees

Kit Tilly

By Kit Tilly, PhD

How would you like to worry about tick bites all year ‘round? Or, what if mountain pine beetle or garden pest infestations were annual events, and no longer cyclical? These scenarios are becoming more likely as our climate warms. Not only are our current arthropod pests likely to have longer active and reproductive seasons, but other arthropods (the group composed of insects, spiders, ticks, and related organisms) are expanding their ranges northward. These changes will affect many aspects of our lives. Ticks and mosquitoes having more active days per year, expanded ranges, and possibly increased numbers of reproductive cycles per year will increase our risk of getting tick- and mosquito-borne diseases, such as Colorado tick fever and West Nile virus. Expanding ranges could introduce new diseases, such as Zika virus and Dengue fever. These diseases would not only adversely affect human health, but could impact domestic and wild animals.

Global warming effects on arthropods will also likely create additional pressures on our forests and agriculture lands. Cold winters and early frosts have historically kept mountain pine beetles in check, by reducing the number that overwinter in marginal habitat. In fact, mountain pine beetles may serve as a selective force, leading to trees that are relatively pest-resistant.  Recent late frosts and autumn blustery weather recently allowed the beetles to survive east of the Rockies in Canada, which may allow them to spread through the boreal forest to eastern North America (Diana Six, Professor of Forest Entomology/Pathology, University of Montana). As growing seasons increase in length, agricultural and garden pests may be able to have more reproductive cycles per year, which, coupled with increased pesticide-resistance, would lead to reduced yields of important food crops. Although we don’t expect plagues of locusts any time soon, those may be in our future too.

Another potential impact of climate change on arthropods is declines in beneficial insects and spiders. Native pollinators and honeybees have been struggling in recent times, in part because of human expansion into natural areas, but also in response to decreasing habitat as a consequence of global warming.

Why does it seem that global warming is good for pests, but bad for beneficial arthropods? One reason is that many pests are invasive, meaning that they come from elsewhere and are expanding opportunistically into new places. These invasive insects are kept in check by predators in their native ecosystems, but have no such checks when they expand into new territory. In contrast, native arthropods have evolved over long periods in their habitats and struggle to keep up with a rapidly changing environment. Arthropods have no way to regulate their body temperatures, so are particularly vulnerable to increasing temperatures.

Are there things we can do to support native insects and discourage the invaders? One big thing is to plant native species in our gardens and around our homes. A second is to preserve open land. Finally, encouraging predators of insects, like birds and spiders, can help keep pests in check.

A recent National Geographic article (05.2020; p.40) details significant declines in both insect species and numbers of individuals per species. The article describes some of the ecosystem services provided by insects, which include serving as food for birds, bats, and amphibians, decomposing carcasses and feces, controlling other insects that are agricultural pests, pollinating, and engineering soil to hold water and nutrients. The article also provides possible explanations for the decline in insects, with climate change topping the list.


Suggestions for Reducing Your Carbon Footprint

By Bill Salterburg

When thinking about solving the problem of global warming, it is easy to be overwhelmed by the magnitude of the action needed. Radical national and global reductions in carbon emissions will be required to avoid more than a 2 degree increase in temperature, and these radical reductions will require action at the national level.
Despite this, actions at the individual and local levels are important. Every reduction in emissions contributes to the overall reduction that we need. Plus, our actions can inspire our friends and neighbors. Likewise, local action can lead to action at the state and national levels. The coronavirus pandemic has imposed big changes on our lives, which we should see as an opportunity to re-examine our values and actions and to decide what is really important to us.

For those who would like to make changes at the level of individual action, there are many small changes that can add up to a big change, if we all make them. These changes can occur in our homes and in the way we drive that will save money and reduce our carbon footprint. Below are some considerations. First, we will look at changes in the home. Secondly, we will consider transportation and its impact. Finally, our role in our community will be briefly addressed.

Here are some considerations for our homes to make them more efficient and environmentally friendly:

  • Turn the thermostat down, or up in the cooling season. Programmable thermostats make this easy.
  • Unplug appliances that are not in use. Turn the lights off.
  • Address energy leaks. Caulk around windows and upgrade or replace worn weather stripping around doors.
  • Lower the temperature of the water heater. 120 degrees is adequate for most purposes.
  • If the distance from your water heater to kitchen or bathroom is far, an inline hot water recirculating pump can be installed, giving instant hot water and saving money and energy. These start at about $60.00 and are a good investment in many homes.
  • Replace old appliances with more energy efficient models. Replace incandescent light bulbs with LED bulbs, which last longer and use less power for the same light.


Bigger home improvement projects are also a consideration. Here are some to explore:

  • Consider talking to one of our local solar panel installers. Prices are dropping every year, making the right setup very cost effective. With the addition of a solar setup, often with rooftop panels, solar can be converted to electrical energy as sunshine allows. Net metering allows a solar system linked to the electric grid to sell excess power on sunny days and purchased as needed. Otherwise, costly batteries are required to store electrical energy. Northwestern Energy sells electricity to the consumer at 11 cents per kwh. For customers with solar panels, NW is currently buying back energy at this same price, 11 cents. REC, our local cooperative, delivers power at about 8 cents per kwh, but only buys back power at 4 cents per kwh, diminishing financial incentives. Local solar panel companies do indicate that over 90% of their solar setups go to NW Energy customers. If you are a REC customer, you can voice your concern about their buyback policy by making your voice heard at their periodic board meetings or writing to the board.
  • High efficiency natural gas and propane furnaces are available for minimally more initial expenditure. This means less natural gas (or propane, depending on your fuel source), less carbon output, and more savings. Studies have indicated that a high efficiency furnace is one of the most effective ways to reduce our carbon footprint, with co2 emission levels that approach or exceed those of high efficiency ground source heat pumps. External source heat pumps are another fuel efficient option.
  • Consider wood heat, either wood or a wood byproduct, wood pellets. On paper, wood heat can be nearly carbon neutral. A dead tree decomposing on the forest floor emits the same amount of CO2 as does a dry log burning in a wood stove, but there are other factors involved. Wood heat causes air pollution. Missoula has greatly restricted wood heat for this reason. With the Bitterroot Valley growing in population by leaps and bounds, this is an important consideration. Also, there is a monetary and energy cost associated with gathering wood. If dead wood is readily available, and the cost of gathering it is minimal, it may be an inexpensive and environmentally sound alternative to more traditional forced air systems. Pellet stoves are also popular, and the higher efficiency stoves can emit less particulate than conventional wood stoves. With regard to carbon footprint, both pellets and wood are a tossup, assuming dry wood is easily accessed. In this part of the country, unlike in the east, pellets are usually manufactured from scraps and other byproducts at a sawmill, making them relatively low carbon.
    With either wood or pellet stoves, if live wood is cut as an energy source, it ceases to be a renewable, carbon friendly resource.
  • Keep remodeling projects green. Choose insulation carefully, with an eye on efficiency and affordability.


As we all know, most vehicles are powered by gasoline, a major contributor to greenhouse gases. Here are ways we can cut down on our transportation footprint:

  • Drive less. During this current pandemic, people are driving less, but prior to this time, our annual yearly mileage has gone up. Planning trips to the store, rather than going daily reduces cost and fuel burned. Taking advantage of community resources, such as the I Ride shuttle system between Hamilton and Missoula, is another opportunity to save on gas consumption and can make the commute trip less stressful. Carpooling can decrease our carbon footprint, get us to work faster, and lessen the parking burden while we are at work.
  • Recreate close to home. Consider more fuel efficient recreational vehicles, or get even closer to nature with a tent. We are Montanans, and love the great outdoors. So often, however, we have great recreational opportunities in our own backyard. Our public lands are a gift, and it would be a tragedy to not take advantage of them. Nevertheless, we can keep many of our outings a little closer to home, saving the big trips for rare occasions. Shorter, local outings may also keep everyone safer during this current pandemic.
  • Accelerate a little slower, brake a little lighter. Both of these are proven to improve fuel efficiency and reduce repair/maintenance bills. Inflate tires properly.
  • Buy and drive fuel efficient vehicles. Consider hybrids and electric cars. Save less efficient vehicles for the jobs they were intended. We are still waiting for an electric charging station in Ravalli County. Keep in mind, also, that electric cars are not perfect solutions. One study indicated that recharging an electric car with electricity obtained exclusively from a coal fired power plant actually increased atmospheric CO2 compared to a gasoline powered car getting 29 mpg.


Our path must be toward totally renewable energy sources. Coal fired power plants continue to emit a high volume of atmospheric CO2, but recent studies have indicated that even hydropower, touted by our electric suppliers as a carbon neutral energy source, is now known to increase atmospheric methane, a greenhouse gas that is 30 times more potent per molecule than CO2.

When discussing our present climate crisis and the changes we can consider to combat this crisis, community involvement is key. Global temperatures continue to rise.

Climate experts are calling for immediate change. Open and spirited discussions with neighbors, friends and co-workers are imperative. Being aware and involved with all levels of government legislation is equally important. The path we take determines the outcome that we will experience. Exercise your right to vote, and urge those you encounter to do the same.