Climate Exposure of U.S. National Parks in a New Era of Change
Climate change is ongoing across the national park system; an overwhelming majority of parks are already at the extreme warm end of their historical conditions. This is a core finding from recently published research by NPS scientists. This study updates the basic climate inventories of 289 national park units.
The findings from this research can inform climate change adaptation by helping park managers, planners, and interpreters to understand how recent climates compare to past conditions. For example, these findings may be used to characterize park exposure to recent climate change in a vulnerability assessment; develop plausible and divergent futures for use in a climate change scenario planning workshop; and synthesize desired future conditions (i.e., reference conditions) for use management plans.
Here, as summary, we present results on which parks experienced “extreme” recent conditions (past 10, 20, and 30 year intervals) relative to the 1901–2012 historical range of variability for seven temperature variables (annual mean, maximum of the warmest month, minimum of the coldest month, mean of the wettest quarter, mean of the driest quarter, mean of the warmest quarter, and mean of the coldest quarter) and seven precipitation variables (annual total, wettest month, driest month, wettest quarter, driest quarter, warmest quarter, coldest quarter). Parks were categorized as “extreme” for temperature or precipitation if the most recent 10, 20, and 30 year intervals, on average, exceeded 95% of the historical range of conditions for any of the seven associated climate variables. As an example, at Everglades National Park, annual mean temperature measured over the past 10, 20, and 30 year intervals has on average been warmer than 97% of all periods of equal length since 1901. Analyses for each park included areas within 30-km (18.6-mi) of the park’s boundary to evaluate recent climate changes in a landscape context.
Results for “extreme” temperature:
- 235 of 289 parks (81%) were categorized as “extreme warm”, 2 parks (1%) as “extreme cold,” 1 park (<1%) was both “extreme warm and cold,” and 51 parks (17%) did not have any recent extreme temperature variables.
- The two most common extreme warm variables for parks were mean temperature of the warmest quarter (170 parks, 59%) and annual mean temperature (158 parks, 55%).
Results for “extreme” precipitation:
- 78 parks (27%) were “extreme wet,” 43 parks (15%) were “extreme dry," 2 parks (2%) were both “extreme wet and dry,” and 166 parks (57%) did not have any recent extreme precipitation variables.
- The most common extreme wet variables were annual precipitation (44 parks, 15%) and precipitation of the wettest quarter (44 parks, 15%), while the most common extreme dry variables were precipitation of the driest quarter (17 parks, 6%) and wettest quarter (16 parks, 6%).
These results show how recent climatic conditions are already shifting beyond the historical range of variability at many parks. Ongoing and future climate change will likely affect all aspects of park management, including natural and cultural resource protection, park operations and visitor experience. Research such as this can help parks develop effective management plans grounded in comprehension of past dynamics, present conditions, and projected future change.
Last updated: December 14, 2018