How the Climate is Changing in the Great Basin

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Words like “unusual” and “extreme” are now everyday verbiage used to describe our weather and climate. We may sense that our environment is changing and wonder about the impact on health to Nevadans. Gaining knowledge about climate change and our Great Basin’s climate is key to effective advocacy as nurses.

What is occurring on a planetary scale?

During the last 600 million years, Earth has mostly been in a warmer “greenhouse” state when the poles had forests and polar seas were warm. But since hominoids appeared and throughout the previous 30 million years the planet has been in a cool “icehouse” state characterized by continental-based ice sheets at high latitudes. Scientific evidence shows that an enhanced greenhouse effect is underway. Alarmingly, levels of atmospheric CO2 are rapidly rising, and atmospheric/oceanic global temperatures are rising in response. It is anticipated that global temperatures will continue to rise throughout the 21st Century challenging the adaptive capacity of ecosystems and humans. Public health planning and preparations are already underway for current and future climate-related impacts appearing in our backyard (Figure 1 – note Southwest).  

Figure 1.

What does this mean for human health?

The climate is changing and our increasing population is living in vulnerable locations at risk for wildfires, floods, mudslides, insect vectors of disease, drought and dust storms. Nurses treat the human response to actual or potential health problems. Hence, our changing climate is challenging nursing to enhance environmental health promotion and educational interventions in our practice. For example, since the large Rim fire of 2013 northern Nevada school nurses have developed and instituted protocols to protect their student populations from future wildfire smoke exposures. We as nurses have the opportunity to develop new initiatives to prevent disease and maintain health for chronic disease populations in the face of a changing climate and ecosystem. Furthermore, we can institute changes in our own lives and institutions to minimize greenhouse pollution.

Figure 2.

How is the climate changing in our Great Basin?

Precipitation: The Great Basin is a naturally dry environment. All precipitation evaporates, sinks underground or flows into rivers and lakes. The creeks, streams, or rivers of the Great Basin find no outlet to either the Gulf of Mexico or the Pacific Ocean. Winter is the primary wet season, though precipitation and lightning can occur during summer from the Southwest Monsoon. Variability in year-to-year precipitation can be high; see for example annual precipitation for Nevada from 1895-2013 in Figure 3. Even with the Great Basin’s already low annual precipitation amounts on average, the region can become even drier from protracted periods of drought (a common natural occurrence; Figure 4). There has not been an overall increasing or decreasing trend in Great Basin annual precipitation over the last 100 years. However, extreme precipitation events such as daily amounts have slightly increased.

Climate models project that if the carbon emission trend continues upward as it has been, then the Great Basin could become annually much warmer and drier. Soil moisture is related to precipitation and temperature, and is expected to overall become drier. Soil-related bacterial and fungal pathogens could become an increasing problem in our future climate. More extreme precipitation events (both in the form of drought and flood) are expected as a result of climate change.

Figure 3.

Figure 4.

Wildfires are a natural part of the Great Basin landscape and occur to varying extent every year (Figure 5). Fuels for fires are dependent on climate conditions, whether moisture for seed germination and vegetation growth, or drying and curing that make the fuels readily available to burn. Lightning is a primary ignition source for Great Basin fires, but the increasing population has increased the human source for ignitions.
Since wildfire is so closely related to temperature and precipitation, it is not surprising that the climate change projections for this Century (warmer and drier) means increased potential for more fires and larger burned areas. Wildfires pose public health risks both from fire and smoke because of expansion of the wildland-urban interface.

Figure 5.

Source: Bureau of Land Management Central Basin and Range Rapid Ecoregional Assessment Report.

Snowpack: Much of the Great Basin relies on winter snow supply for the summer water demand. Like rainfall, snowfall can be highly variable from year-to-year (Figure 6). The snow depth throughout the winter can be more important than the amount fallen. It is the snowpack that feeds the lakes, rivers and reservoirs of the region, and provides soil moisture for vegetation.
Climate change models project that the historical snowline will get higher in elevation as a result of regional warming. This means less snowpack, and elevations accustomed to snow will experience more rain events. With the potential increase in extreme rainfall, this could mean more rain-on-snow events leading to further floods.

Figure 6.

Temperatures in the Great Basin vary greatly between winter and summer, with daily values historically ranging from below zero to above 100. The overall trend for annual mean temperatures has been increasing over the years (see Nevada example in Figure 7). However, it is the nighttime minimum temperatures that are mostly driving this trend – or to say another way, nights are much warmer than they used to be.
Climate models project increased overall warming for the Great Basin during this Century largely driven by greenhouse gas increases. Warmer temperatures will enhance soil moisture drying and plant evapotranspiration. This in turn can enhance drought conditions. But globally, increased warming also means increased moisture in the atmosphere, and this can lead to more extreme precipitation events.

Exercise: Assess your current “carbon footprint” and see if there are improvements you can make to reduce greenhouse pollutants!

EPA’s Climate Change Terms

Climate: is usually defined as the "average weather," or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands of years. The classical period is 3 decades.
Climate Change refers to any significant change in the measures of climate lasting for an extended period of time.

Weather: atmospheric condition at any given time or place. It is measured in terms of such things as wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation. In most places, weather can change from hour-to-hour, day-to-day, and season-to-season.

Climate System: the five physical components (atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere) that are responsible for the climate and its variations.

Adaptive Capacity: the ability of a system to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with the consequences.

Carbon Footprint: the total amount of greenhouse gases that are emitted into the atmosphere each year by a person, family, building, organization, or company.

Carbon Sequestration: terrestrial, or biologic, carbon sequestration is the process by which trees and plants absorb CO2, release the oxygen, and store the carbon.

Desertification: land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities.

Enhanced Greenhouse Effect: the concept that the natural greenhouse effect has been enhanced by increased atmospheric concentrations of greenhouse gases (such as CO2 and methane) emitted as a result of human activities.

Forcing Mechanism: a process that alters the energy balance of the climate system, i.e. changes the relative balance between incoming solar radiation and outgoing infrared radiation from Earth. Such mechanisms include changes in solar irradiance, volcanic eruptions, and enhancement of the natural greenhouse effect by emissions of greenhouse gases.

Mitigation: a human intervention to reduce the human impact on the climate system; it includes strategies to reduce greenhouse gas sources and emissions and enhancing greenhouse gas sinks.

Natural Variability: variations in the mean state and other statistics (such as standard deviations or statistics of extremes) of the climate on all time and space scales beyond that of individual weather events. Natural variations in climate over time are caused by internal processes of the climate system, such as El Niño, as well as changes in external influences, such as volcanic activity and variations in the output of the sun.


References & Resources


Dr. Timothy J. Brown
Director, Western Regional Climate Center
Desert Research Institute, NV

Dr. Bernadette M. Longo, RN
Chair, NNA Environmental Health Committee
University of Nevada Reno