This fact sheet provides a summary of Climate Change in Nevada, a report written as part of Nevada’s State Climate Initiative. The full report is available on the Nevada Climate Initiative website, ClimateAction.nv.gov.  Summarized in this fact sheet are specific details about how climate change has already and will continue to impact the state of Nevada and strategies that can be used to prepare for these changes. It highlights historical trends and future projections for some major climate variables and how they may affect public health, water resources, the environment, hospitality and agriculture, with the goal of better informing decision makers and the general public.

OVERVIEW OF HISTORICAL AND PROJECTED TRENDS

The current release of carbon into the atmosphere is unprecedented and more rapid than at any time over the past 56 million years^1,2. In recent decades, Nevada has witnessed increasing temperatures, extreme droughts, loss of snow, increasing evaporative demand (i.e., atmospheric thirst) and a number of large wildfires. We are observing changes in the present, and best projections indicate that these trends will continue (Table 1). 

Climate change has come home.

Just as the current climate varies from place to place in the state, future climate change will also vary for different locations with different impacts on specific communities, economic sectors and ecosystems. The amount of warming that Nevada will face in the future depends on whether greenhouse gas emissions are allowed to continue increasing, or whether they are reduced rapidly over the coming decades. Scientists are extremely confident that greenhouse gas emissions have already caused the earth to warm. More emissions will cause more warming and other changes to climate. Tables 2 - 6 list ways that our changing climate is most likely to affect the lives of Nevadans.
 

 
Table 1. Historical and Future Climate Changes in Nevada

INCREASING HEAT AND HEAT WAVES

In Nevada, average temperatures have been increasing over time. In fact, eight of the 10 warmest years since 1895 have occurred between 2000 and 2020. Although temperatures throughout the state are increasing, the rate of warming is not the same everywhere. Urban areas, for example, are getting hotter faster than rural areas. Average temperatures are expected to increase in all seasons, but the warming is likely to be greatest in the summer and fall. Higher temperatures affect multiple sectors, including public health, agriculture, hospitality, the environment and water resources. 

Increasing average temperatures will also lead to more frequent and severe heat waves and hotter days and nights. The term heat wave generally refers to spells of much hotter than normal weather, sufficient to be unpleasant or even unsafe. The number of very warm days—when daytime temperatures exceed 95 F—has already increased across the state, with the largest increases in southern and northwestern Nevada. The severity and number of extremely hot days and warm nights are expected to increase. Extremely high temperatures pose a danger to human life and physical and mental health^3,4, to transportation, the electrical grid,  ecosystems, livestock, and crops. Extreme heat increases fire risk for some vegetation types⁴ and can also negatively impact wildlife⁶. Extreme heat also impacts air quality, as higher temperatures are associated with increased ozone levels⁷. 

Urban heat islands occur in developed areas that retain heat, especially at night, leading to higher temperatures relative to more rural, non-developed surrounding areas. We are already seeing the effects of urban heating in Reno and Las Vegas. Although urban heat islands are not caused by global greenhouse gas emissions, urban heating is expected to continue, leading to warming in cities beyond what is seen in regional climate projections. 

The amount of warming that Nevada will face in the future depends on whether greenhouse gas emissions continue to grow or whether they are reduced rapidly over the coming decades. Projections of warming range from 4 F - 6 F throughout Nevada in the near term (the next few decades), but long-term (the last few decades of the 21st century) changes depend on society’s emissions-related choices today. Nevada will experience greater warming with higher emissions.
 

Table 2. Impacts of Heat and Heat Waves in Nevada

PRECIPITATION AND DROUGHT

As the driest state in the nation, Nevada is particularly vulnerable to changes in water supply that are expected as temperatures warm in Nevada and across the West. Las Vegas and Reno rely on water supplies that come primarily from mountains outside of Nevada—in the Upper Colorado River Basin and the Sierra Nevada, but local rain and snow feed the streams, springs and wells that many rural communities, farms and ranches rely on. Reliable water supply is critical for maintaining human health, energy supply, and productive agriculture, as well as healthy rangelands, forests and riparian zones.

Nevada’s precipitation already varies substantially from year to year, which makes climate projections of future precipitation difficult to interpret with confidence^8,9. Moreover, some models predict more precipitation, some less, and some almost no change. The average across many recent climate models, however, suggests a possible small increase in average precipitation across all but the southern tip of Nevada in the near term. Even if average precipitation does increase, there will still be dry years. 

Despite these uncertain projections of precipitation, drought is fairly likely to increase in intensity and frequency because of higher temperatures. With no change in precipitation (or even an increase), higher temperatures alone will lead to a change from snow to rain, which reduces the amount of water we can store in winter snowpack for use later in the year. High temperatures also lead to more evaporative demand. Evaporative demand—the atmospheric thirst driven by temperature, wind, humidity and solar radiation—plays an important role in droughts and can be particularly impactful in arid places such as Nevada¹⁰  (Table 3). When evaporative demand is higher than normal, soils dry out faster and vegetation becomes drier, leading to increased fire risk and degraded ecosystems. Over the past 40 years, evaporative demand has strongly increased in Nevada, with the fastest increases in the west-central part of the state. Recent precipitation shortages, combined with increasing evaporation, have already led to hydrologic (water supply) droughts being more common since the start of the 21st century. Climate projections indicate this trend will continue through the end of the 21st century. 
 

Table 3. Drought Impacts in Nevada

SNOW LOSS AND SNOW MELT CHANGES 

With higher temperatures, more of the storms will bring rain instead of snow, even at high altitudes. In the near term, between 5% and10% more of the precipitation is anticipated to fall as rain rather than snow. Basins around Lake Tahoe and in northwestern Nevada are projected to experience 10% to15% more rain rather than snow. Less snow and earlier snowmelt affect water management in Nevada, as snow serves as a natural reservoir that slowly provides water to downstream ecosystems, agricultural land and communities. The loss of snow also has implications for winter recreation, which would impact quality of life for many residents and recreational tourism in Nevada. 

With less precipitation falling as snow, and with snowpack melting earlier due to the warming winters, the amount of water in the snowpack on April 1—the time of year when snowmelt normally peaks—is projected to decline 30% to 50% by the end of century in most basins in the state¹¹. These changes are already being observed across the northern parts of the state and across the West ^12,13,14,15.

Warming would also mean longer growing seasons for native plants and agricultural crops alike, by anywhere from about three to six weeks in most basins in the near term. However, if precipitation falls as rain rather than snow, the state’s highlands and riparian areas will be drier by the time summer arrives^16,12. By the end of the century, the timing and amount of surface-water are expected to be increasingly out of sync with irrigation demands, further challenging water management in Nevada. 
 

Table 4. Impacts of Snow Loss on Nevada

SEVERE FLOODING

While well known as the driest state, Nevada has experienced many catastrophic floods. Because a warmer atmosphere can carry more water^17,18, the most extreme storms are expected to become even more extreme. For example, projected near-term and long-term changes in peak annual  runoff rates (the maximum daily runoff rate occurring during the average year) are projected to increase more than 25% to 50% above historical peak rates across much of the state, especially in and around many mountain ranges.

Table 5. Flooding Impacts in Nevada

WILDFIRE RISK AND INVASIVE SPECIES

Fire is controlled by weather, topography and fuels. Climate influences both weather and fuels. In Nevada, four of the five years with the largest area burned have occurred since 2005 (considering the consistent records collected since 1985). Both wet and dry conditions can increase fire risk due to the interplay between vegetation production during wet periods and vegetation drying during dry periods. For example, when a wet winter is followed by a dry spring and summer, the wet winter promotes the growth of grasses and other fine fuels, and the subsequent dry spring and summer results in the drying and curing of those fuels. These fuels are then primed for easy fire spread if an ignition occurs. This dynamic between the production and curing of fuels suggests that seasonal droughts can be a larger factor than multiyear droughts in Nevada and the Great Basin¹⁹.

In Nevada, increased fire frequency promotes the establishment and success of invasive species such as cheatgrass and red brome. The proliferation of these invasive species provides quick-burning fuels that contribute to the start and spread of fire, which furthers the spread of more invasive species^20,21.

In addition to wildfire’s direct risk to public safety, residential and commercial property, infrastructure, business operations, and livestock health and safety, wildfire can pose widespread risks to public health. Smoke from wildfires can travel hundreds of miles, impacting the health of Nevadans well beyond the immediate threat from the fire itself²². Wildfire smoke is associated with respiratory issues and hospitalization, especially for the elderly and children under four²³. Emergency room visits for those with asthma increase as a result of wildfire smoke as well²⁴. Power shutoffs aimed at reducing the risk of wildfire ignition can pose hazards to those who rely on electricity for medical devices and can economically impact families and businesses.
 

Table 6. Wildfire Impacts in Nevada

AUTHORS

• Stephanie McAfee, Associate Professor and Nevada State Climatologist, University of Nevada, Reno Department of Geography and Extension
• Christina Restaino, Assistant Professor and Natural Resources Specialist, University of Nevada, Reno Extension
• Kerri Jean Ormerod, Assistant Professor, University of Nevada Reno Department of Geography and Extension
• Michael Dettinger, California-Nevada Climate Applications Program, Scripps Institution of Oceanography, UC San Diego
• Daniel McEvoy, Western Regional Climate Center & California-Nevada Climate Applications Program, Desert Research Institute
• Julie Kalansky, California-Nevada Climate Applications Program, Scripps Institution of Oceanography, UC San Diego
• Daniel Cayan, California-Nevada Climate Applications Program, Scripps Institution of Oceanography, UC San Diego
• Matthew Lachniet, Professor and Chair, Department of Geoscience, University of Nevada, Las Vegas
• Susanne Moser, California-Nevada Climate Applications Program
• Kristin VanderMolen, Western Regional Climate Center & California-Nevada Climate Applications Program, Desert Research Institute
• Tamara Wall, Western Regional Climate Center & California-Nevada Climate Applications Program, Desert Research Institute

REFERENCES

¹ Foster, GL, P Hull, DJ Lunt, JC Zachos (2018) Placing our current ‘hyperthermal’ in the context of rapid climate change in our geological past. Philosophical Transactions of the Royal Society A, 376, 20170086.

² Zeebe, RE, A Ridgewell, JC Zachos (2016) Anthropogenic carbon release rate unprecedented during the past 66 million years. Nature Geoscience, 9, 325-329.

³ Bandala, ER, K Kebede, N Jonsson, R Murray, D Green, JF Mejia, PF Martinez-Austria (2019) Extreme heat and mortality rates in Las Vegas, Nevada: inter-annual variations and thresholds. International Journal of Environmental Science and Technology, 16, 7175-7186.

⁴ Zuo, J, S Pullen, J Palmer, H Bennetts, N Chileshe, T Ma (2015) Impacts of heat waves and corresponding measures: a review. Journal of Cleaner Production, 92, 1-12.

⁵ Chapman, L, JA Azevedo, T Prieto-Lopez (2013) Urban heat & critical infrastructure networks: a viewpoint. Urban Climate, 3, 7-12.

⁶ Albright, TA, D Mutibwa, AR Gerson, EK Smith, WA Talbot, JJ O’Neill, AE McKechnie, BO Wolf (2017) Mapping evaporative water loss in desert passerines reveals an expanding threat of lethal dehydration. Proceedings of the National Academy of Sciences, 114, 2283-2288.

⁷ Wise, EK and AC Comrie (2005) Meteorologically adjusted urban air quality trends in the Southwestern United States. Atmospheric Environment, 16, 2969-2980.

⁸ Dettinger, M, J Anderson, M Anderson, LR Brown, D Cayan, E Maurer (2016). Climate Change and the Delta. San Francisco Estuary and Watershed Science, 14, 3.

⁹ Dettinger, MD, FM Ralph, T Das, PJ Neiman, DR Cayan (2011) Atmospheric rivers, floods, and the water resources of California. Water, 3, 445-478.

¹⁰ Hobbins, M, D McEvoy, C Hain (2017) Evapotranspiration, Evaporative Demand, and Drought. In Drought and Water Crises: Integrating Science, Management, and Policy, 2^nd edition, DA Wilhite and RS Pulwarty (eds.) CRC Press, Boca Raton, FL.

¹¹ Dettinger, MD (2020) Projections of 21^st century climate-change impacts for Nevada hydographic basins.

¹² Fritze, K, IT Stewart, E Pebesma (2011) Shifts in western North American snowmelt runoff regimes for the recent warm decades. Journal of Hydrometeorolog, 12, 989-1006.

¹³ Knowles, N, MD Dettinger, DR Cayan (2006) Trends in snowfall versus rainfall in the western United States. Journal of Climate, 19, 4545-4559.

¹⁴ Mote, PW, S Li, DP Lettenmaier, M Xiao, R Engel (2018) Dramatic declines in snowpack in the western US. npj  Climate and Atmospheric Science, 1, 2.

¹⁵ Stewart, IT, DR Cayan, MD Dettinger (2005) Changes toward earlier streamflow timing across Western North America. Journal of Climate, 18, 1136-1155.

¹⁶ Harpold, AA, NP Molotch, KN Musselman, RC Bales, PB Kirchner, M Livtak, PD Brooks (2014) Soil moisture response to snowmelt timing in mixed-conifer subalpine forest. Hydrological Processes, 29, 2782 – 2798.

¹⁷ Gershunov, A, T Shulgina, RES Clemesha, K Guirgui, DW Pierce, MD Dettinger, DA Lavers, DR Cayam, SD Polade, J Kalansky, FM Ralph (2019) Precipitation regime change in Western North America: The role of atmospheric rivers. Scientific Reports, 9, 9944.

¹⁸ Kunkel, KE, TR Karl, DR Easterling, K Redmond, J Young, X Yin, P Hennon (2013) Probable maximum precipitation and climate change. Geophysical Research Letters, 40, 1402-1408.

¹⁹ Pilliod, DS, JL Welty, RS Arkle (2017) Refining the cheatgrass–fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends. Ecology and Evolution, 7, 8126-8151.

²⁰ Bradley, BA, CA Curtis, EJ Fusco, JT Abatzoglou, JK Balch, S Dadashi, M-N Tuanmu (2017) Cheatgrass (Bromus tectorum) distribution in the intermountain Western United States and its relationship to fire frequency, seasonality, and ignitions. Biological Invasions, 20, 1493-1506.

²¹ Williamson, MA, E Fleishman, RC Mac Nally, JC Chambers, BA Bradley, DS Dobkin, DI Board, FA Fogarty, N Horning, M Leu, MW Zillig (2019) Fire, livestock grazing, topography, and precipitation affect occurrence and prevalence of cheatgrass (Bromus tectorum) in the central Great Basin, USA. Biological Invasions, 22, 663-680.

²² Moeltner, K, M-K Kim, E Zhu, W Yang (2013) Wildfire smoke and health impacts: a closer look at fire attributes and their marginal effects. Journal of Environmental Economics and Management, 66, 476-496.

²³ Delfino, RJ, S Brummel, J Wu, H Stern, B Ostro, M Lipsett, A Winer, DH Street, L Zhang, T Tjoa, DL Gillen (2009) The relationship of respiratory and cardiovascular hospital admissions to the southern California wildfires of 2003. Occupational and Environmental Medicine, 66, 189-197.

²⁴ Kiser, D, WJ Metcalf, G Elhanan, B Schneider, K Schlauch, A Joros, C Petersen, J Grymski (2020) Particulate matter and emergency visits for asthma: a time-series study of their association in the presence and absence of wildfire smoke in Reno, Nevada, 2013-2018. Environmental Health, 19, 92.

Published by: McAfee, S., Restaino, C., Ormerod, K., Dettinger, M., McEvoy, D., Kalansky, J., Cayan, D., Lachniet, M., Moser, S., VanderMolen, K., Wall, T., 2021, Climate Change Impacts in Nevada, Extension | University of Nevada, Reno FS-21-06

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