Climate Change Impacts to the Lake Tahoe Basin

Lake Tahoe is the largest alpine lake in North America and a popular tourist destination, famous for its water clarity and summer and winter recreational opportunities. Climate change is already placing environmental and economic stress on Lake Tahoe’s communities, and understanding and mitigating climate change impacts to the Lake Tahoe Basin is necessary. This conceptual model is meant to help visualize and communicate anticipated impacts of climate change in the Lake Tahoe Basin. More information about each impact is below. 

Climate change is expected to increase temperature and make precipitation more variable in the region. The impacts from climate change are already being seen; the average temperature has been rising over the past decade, and this trend is expected to amplify in the future (California Tahoe Conservancy, 2020). Warmer temperatures and more variable precipitation will lead to several impacts of economic and ecological importance, including the following:  

•    More frequent and intense wildfires: Increased temperature and more variable precipitation will lead to more drought periods and more insect outbreaks that kill trees, both of which (in addition to the hotter temperatures themselves) will increase the frequency and strength of wildfires. Total area burned by wildfires per decade is expected to be over 60% larger at the end of the century than now, and moderate and high burn severity areas are projected to increase the most (California Tahoe Conservancy, 2020). Secondary impacts due to more wildfires include declining lake water clarity, less opportunity for summer recreation, and infrastructure damage.
•    Worse lake water clarity: Increased temperature will lead to a shift from precipitation falling as rain instead of snow. Further, more variable precipitation will lead to more flooding events. Increased rainfall and acceleration of snowmelt will increase erosion and runoff. Lake clarity is thus expected to decline due to an increase in sediment deposition (California Tahoe Conservancy, 2020). 
•    Infrastructure damage: More extreme weather, flooding, erosion, and wildfire will all contribute to infrastructure damage. In recent years, the Tahoe area has already seen rockslides into major roads. There are not many roads going in and out of the Basin, so road closures can lead to significant issues for the tourism economy. 
•    Less summer recreation opportunities: Tahoe attracts 24 million visitors every year, drawn to summer and winter recreation opportunities (California Tahoe Conservancy, 2020). In summer, tourists are attracted to the warm weather and lake recreation opportunities such as swimming, kayaking, and boating. Increasing wildfire and declines in water clarity may reduce Tahoe’s appeal to summer visitors. Further, boating in Tahoe is not yet adapted for the lower lake levels expected in the more frequent (and already experienced) drought periods – during droughts in recent years, the boat docks no longer reach the lake level. Adaptive infrastructure for boat docks is currently in city plans (The City of South Lake Tahoe, 2020), highlighting already increasing costs presented by climate change. 
•    Less winter recreation opportunities: Increased temperatures, reduced snowpack, more drought, and more extreme weather events will shorten winters and reduce opportunities for winter recreation like skiing and snowboarding. The large winter recreation economy may be harmed, including repercussions for Tahoe’s 15 ski resorts employing thousands of locals. 

•    More invasive aquatic species: Summer tourism and boating already necessitates invasive species management, and the issues will amplify under climate change. Specifically, higher temperatures can increase the nearshore lake temperature, an area of particular vulnerability to invasive species. Invasive species can impact lake water clarity and harm native species.
•    Less habitat for native species: Tahoe’s native aquatic and terrestrial flora and fauna will be harmed by climate change. The amount of habitat that satisfies the species’ evolutionary needs will change under increasing temperatures and precipitation variability. Meadows are particularly at risk from rising temperatures and decreased snowpack and are projected to decline under climate change. Finally, higher prevalence of invasive species can also negatively impact native species, such as through competition or predation. 

The Lake Tahoe Basin is a unique location of economic and environmental importance. Climate change mitigation and adaptation are necessary to preserve the beautiful ecosystems and maintain the summer and winter recreation opportunities that make it exceptional. 

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References
California Tahoe Conservancy. (2020). Integrated Vulnerability Assessment of Climate Change in the Lake Tahoe Basin. https://tahoe.ca.gov/wp-content/uploads/sites/257/2020/04/Integrated-Vulnerability-Assessment-of-Climate-Change-in-the-Lake-Tahoe-Basin_2020.pdf
The City of South Lake Tahoe. (2020). City of South Lake Tahoe Climate Action Plan. https://www.cityofslt.us/DocumentCenter/View/14460/SLT-CAP-DRAFT