Montana State University, Bozeman. Photo courtesy of Scott Bischke.



adaptation — Actions taken to help communities and ecosystems better cope with potential negative effects of climate change or take advantage of potential opportunities.

adaptive capacity — Ability of a person (or society) to cope with climate change. Used to calculate vulnerability.

adverse childhood experiences — Potentially traumatic events that occur in childhood. Sometimes referred to as ACEs. These events can include violence, abuse, neglect, separation, substance abuse, mental health problems, or witnessing a family suicide. ACEs are linked to chronic health problems, mental illness, and substance misuse in adulthood. ACEs can also negatively impact education and job opportunities. ACEs can be prevented.

anthropogenic Originating in human activity; human caused.

aquifer — A body of permeable rock that can contain or transmit groundwater.

atmospheric carbon dioxide (CO2) — The amount of carbon dioxide in Earth’s atmosphere. Although the proportion of Earth’s atmosphere made up by CO2 is small, CO2 is one of the most potent greenhouse gases and directly related to the burning of fossil fuels. Atmospheric carbon dioxide levels in Earth’s atmosphere are at the highest levels in an estimated 3 million yr and these levels are projected to increase global average temperatures through the greenhouse effect.

attribution — Identifies a source or cause of something.

basin — A drainage basin or catchment basin is an extent or an area of land where all surface water from rain, melting snow, or ice converges to a single point at a lower elevation, usually the exit of the basin, where the waters join another body of water, such as a river, lake, reservoir, estuary, wetland, sea, or ocean.

biodiversity — The variety of all native living organisms and their various forms and interrelationships.

chronic disease — A disease or health condition lasting for a long time, usually more than 3 months. Examples include high blood pressure, chronic obstructive lung/pulmonary disease (COLD/COPD), cancer and diabetes.

climate change — Changes in average weather conditions that persist over multiple decades or longer. Climate change encompasses both increases and decreases in temperature, as well as shifts in precipitation, changing risk of certain types of severe weather events, and changes to other features of the climate system.

climate pressures — Events or processes either caused by or made more frequent due to climate change, including increased temperatures, sea-level rise, extreme precipitation events, and more extreme weather, such as storms.

climate variables — Essential information for understanding the Earth's climate, including average annual and season temperature and precipitation.

climate versus weather — The difference between weather and climate is a measure of time. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere "behaves" over relatively long periods of time (i.e., multiple decades).

commodity futures — Buying or selling of a set amount of a commodity at a predetermined price and date.

COVID-19 — Respiratory illness and associated complications caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) that was first detected in humans in late 2019.

direct effect — A primary impact to a system from shifts in climate conditions (e.g., temperature and precipitation), such as direct mortality to species from increased heat extremes.

displacement — Forced migration due to conditions that prevent individuals, families, or communities from sustaining themselves in traditional locations. Those conditions might result from climate change—e.g., sea-level rise, floods, or drought—or social upheaval such as violence, persecution, or economic distress.

downscaling — A general term for procedures that take information known at large scales to make predictions at local scales.

drought — Drought is generally categorized in three ways: 1) meteorological drought, defined as a deficit in precipitation, 2) agricultural drought, commonly understood as a deficit in soil moisture, and 3) hydrological drought, characterized by reduced water levels in streams, lakes, and aquifers.

El Niño-Southern Oscillation (ENSO) — A periodic variation in wind and sea-surface temperature patterns that affects global weather; El Niño (warming phase where sea-surface temperatures in the eastern Pacific Ocean warm) generally means warmer (and sometimes slightly drier) winter conditions in Montana. In contrast, La Niña (cooling phase) generally means cooler (and sometimes wetter) winters for Montanans. The two phases each last approximately 6-18 months, and oscillate between the two phases approximately every 3-4 yr.

ensemble of general circulation models (GCMs)Succinctly: When many different forecast models are used to generate a projection, and outputs are synthesized into a single score or average. This type of forecast significantly reduces errors in model output and enables a level of certainty to be placed on the projections. More broadly: Rather than relying on the outcome of a single climate model, scientists run ensembles of many models. Each model in the ensemble plausibly represents the real world, but as the models differ somewhat they produce different outcomes. Scientists analyze the outputs (e.g., projected average daily temperature at mid century) over the entire ensemble. Those analyses provide both the projection of the future resulting from the ensemble of models, and define the level of certainty that should be placed on that projection.

evaporation — The change of a liquid into a vapor at a temperature below the boiling point. Evaporation takes place at the surface of a liquid, where molecules with the highest kinetic energy are able to escape. When this happens, the average kinetic energy of the liquid is lowered and its temperature decreases.

exposure — The type and magnitude of a climat change. Used to calculate vulnerability.

fire regime — The frequency, severity, and pattern of wildfire.

fire risk — The likelihood of a fire ignition.

fire severity — The magnitude of effects from a fire, usually measured by the level of vegetation or biomass mortality or the area burned.

flood — An overflowing of a large amount of water beyond its normal confines, especially over what is normally dry land.

flood plain — An area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.

food security / insecurity — Describes an individual or community’s ability to reliably access a sufficient quantity of affordable, nutritious food. The USDA defines food security into four categories: 1) high food security means having no food-access problems or limitations; 2) marginal food security means having some anxiety over food sufficiency, but little change in diets or food intake; 3) low food security (i.e., food insecurity) means reduced quality, variety, or desirability of diet, though little or no reduction in food intake; and 4) very low food security (again, food insecurity) means disrupted eating patterns and reduced food intake.

frost days — The annual count of days where daily minimum temperature drops below 32°F (0°C).

general circulation models (GCMs) — Numerical models representing physical processes in the atmosphere, ocean, cryosphere, and land surface. They are the most advanced tools currently available for simulating the response of the global climate system to increasing greenhouse gas concentrations.

greenhouse gas — A gas in Earth’s atmosphere that absorbs and then re-radiates heat from the Earth and thereby raises global average temperatures. The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Earth relies on the warming effect of greenhouse gases to sustain life, but increases in greenhouse gases, particularly carbon dioxide from the burning of fossil fuels, can increase average global temperatures over historical norms.

greenhouse gas emissions — The discharge of greenhouse gases, such as carbon dioxide, methane, nitrous oxide and various halogenated hydrocarbons, into the atmosphere. Combustion of fossil fuels, agricultural activities, and industrial practices contribute to the emissions of greenhouse gases.

global warming — The increase in Earth’s surface air temperatures, on average, across the globe and over decades. Because climate systems are complex, increases in global average temperatures do not mean increased temperatures everywhere on Earth, nor that temperatures in a given year will be warmer than the year before (which represents weather, not climate). More simply: Gobal warming is used to describe a gradual increase in the average temperature of the Earth's atmosphere and its oceans, a change that is believed to be permanently changing the Earth's climate.

groundwater — Water held underground in the soil or in pores and crevices in rock.

health factors — Factors that drive how long and how well people live including, for example, personal behaviors, socioeconomic factors, and the physical environment.

heat index — A measure of perceived heat when humidity, which can make it feel much hotter, is factored in with the actual measured air temperature. (A similar and more familiar term is wind chill factor, a measure of how cold it feels when wind, which can make it feel much colder, is factored in with the actual measured air temperature.)

heat stress — A buildup of body heat generated either internally by muscle use or externally by the environment. Heat exhaustion and heat stroke result when the body is overwhelmed by heat . As the heat increases, body temperature and the heart rate rise.

HEPA — high-efficiency particulate air (filters).

hydrograph — A hydrograph is a graph showing the rate of flow (discharge) versus time past a specific point in a river, or other channel or conduit carrying flow. The rate of flow is typically expressed as cubic feet per second, CFS, or ft3/s (the metric unit is m3/s).

hydrologic cycle — The sequence of conditions through which water passes from vapor in the atmosphere through precipitation upon land or water surfaces and ultimately back into the atmosphere as a result of evaporation and transpiration.

hydrology — The study of water. Hydrology generally focuses on the distribution of water and interaction with the land surface and underlying soils and rocks.

interpolation — The process of using points with known values to estimate values at other unknown points.

intervention — The act of interfering or interceding with the intent of modifying the outcome. In medicine, an intervention is generally undertaken to help treat or cure a condition.

irrigation — Application of water to soil for the purpose of plant production.

legume — Any of a large family (Leguminsoae syn. Fabaceae, the legume family) of dicotyledonous herbs, shrubs, and trees having fruits that are legumes or loments, bearing nodules on the roots that contain nitrogen-fixing bacteria, and including important food and forage plants (as peas, beans, or clovers).

mental health — The condition of being sound mentally and emotionally that is characterized by the absence of mental illness and by adequate adjustment, especially as reflected in feeling comfortable about oneself, positive feelings about others, and the ability to meet the demands of daily life.

metrics — Quantifiable measures of observed or projected climate conditions, including both primary metrics (for example, temperature and precipitation) and derived metrics (e.g., projected days over 90°F [32°C ] or number of consecutive dry days)

metropolitan areas — Areas having at least one urbanized area of 50,000 or more population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.

microclimate — The local climate of a given site or habitat varying in size from a tiny crevice to a large land area. Microclimate is usually, however, characterized by considerable uniformity of climate over the site involved and relatively local when compared to its enveloping macroclimate. The differences generally stem from local climate factors such as elevation and exposure.

micropolitan areas — Areas having at least one urban cluster of at least 10,000 but less than 50,000 population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.

mitigation — Efforts to reduce greenhouse gas emissions to, or increase carbon storage from, the atmosphere as a means to reduce the magnitude and speed of onset of climate change

model — A physical or mathematical representation of a process that can be used to predict some aspect of the process.

organic — A crop that is produced without: antibiotics; growth hormones; most conventional pesticides; petroleum-based fertilizers or sewage sludge-based fertilizers; bioengineering; or ionizing radiation. USDA certification is required before a product can be labeled organic.

oscillation — A recurring cyclical pattern in global or regional climate that often occurs on decadal to sub-decadal timescales. Climate oscillations that have a particularly strong influence on Montana's climate are the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO).

Pacific Decadal Oscillation (PDO) — A periodic variation in sea-surface temperatures that is similar to El Niño-Southern Oscillation, but has a much longer duration (approximately 20-30 yr). When the PDO is in the same phase as El Niño-Southern Oscillation, weather effects are more pronounced. For example, when both are in the warming phase, Montanans may experience an extremely warm winter, whereas if PDO is in a cooling phase, a warm phase El Niño-Southern Oscillation may have a reduced impact.

pandemic — An epidemic of a disease that has spread across a wide geographic region, either multiple continents or worldwide. (Contrast with an epidemic, which is a disease that is actively spreading. Thus, a pandemic is a specific type of epidemic that has spread more widely.)

parameter — A variable, in a general model, whose value is adjusted to make the model specific to a given situation.

pathogen — Microorganisms, viruses, and parasites that can cause disease.

peak flow — The point of the hydrograph that has the highest flow.

permeability — A measure of the ability of a porous material (often, a rock or an unconsolidated material) to allow fluids to pass through it.

pulse crop — Annual leguminous crops yielding from 1-12 grains or seeds of variable size, shape, and color within a pod. Limited to crops harvested solely for dry grain, thereby excluding crops harvested green for food, oil extraction, and those that are used exclusively for sowing purposes.

RCP (representative concentration pathways) — Imagined plausible trends in greenhouse gas emissions and resulting concentrations in the atmosphere used in climate projection models. This analysis uses the relatively moderate and more severe scenarios of RCP4.5 and 8.5. These scenarios represent a future with an increase in radiative forcing of 4.5 or 8.5 watts/m2, respectively. The RCP4.5 scenario assumes greenhouse gas emissions peak mid century, and then decline, while the RCP8.5 scenario assumes continued high greenhouse gas emissions through the end of the century.

resilience — In ecology, the capacity of an ecosystem to respond to a disturbance or perturbation by resisting damage and recovering quickly.

resistance — In ecology, the property of populations or communities to remain essentially unchanged when subject to disturbance. Sensitivity is the inverse of resistance.

runoff — Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the Earth's surface.

scenario — Climate change scenarios are based on projections of future greenhouse gas (particularly carbon dioxide) emissions and resulting atmospheric concentrations given various plausible but imagined combinations of how governments, societies, economies, and technologies will change in the future. This analysis considers two plausible greenhouse gas concentration scenarios: a moderate (stabilized) and more severe (upper-bound) scenario, referred to as RCP4.5 and RCP8.5, respectively.

sensitivity — How sensitive a person is to climate change. Used to calculate vulnerability.

Snow Water Equivalent (SWE) — A common snowpack measurement that is the amount of water contained within the snowpack. It can be thought of as the depth of water that would theoretically result if you melted the entire snowpack instantaneously.

soil moisture — A measure of the quantity of water contained in soil. Soil moisture is a key variable in controlling the exchange of water and energy between the land surface and the atmosphere through evaporation and plant transpiration. 

Sudden Infant Death / Sudden Unexpected Infant Death syndromes (SIDS/SUIDS) — unexplained death, usually during sleep, of a seemingly healthy baby less than a year old. 

transpiration — The passage of water through a plant from the roots through the vascular system to the atmosphere.

vulnerability — The extent to which a person is susceptible to the impacts of climate change.

warm days — Percentage of time when daily maximum temperature >90th percentile.

warm nights — Percentage of time when daily minimum temperature >90th0th percentile.

water quality — The chemical, physical, biological, and radiological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and/or to any human need or purpose.

watershed — An area characterized by all direct runoff being conveyed to the same outlet. Similar terms include basin, sub-watershed, drainage basin, catchment, and catch basin.

weather versus climate — See climate versus weather.

zoonosis (plural, zoonoses) — An infectious disease caused by a bacterium, virus, fungus, or other agent that has moved from non-human animals to humans. Recent examples include Ebola, HIV, and SARS-CoV2.