Joshua Tree National Park has been getting hotter and drier over the past century in large part due to human-caused climate change. Greenhouse gas emissions from fossil fuels such as coal, oil, and natural gas trap heat in the Earth’s atmosphere. In effect, this makes the planet hotter and changes the Earth’s climate systems. These changes lead to more heatwaves, major precipitation events, melting ice caps, rising sea levels, and greater intensity of natural disasters like hurricanes, floods, droughts, and wildfires. Here in Joshua Tree, we are experiencing the effects of climate change. From 1895 to 2016, the annual precipitation dropped by 39 percent, and the average temperature increased by 3℉ (2℃). These changes impact our landscape, our species, and our visitors.
Fewer Joshua Trees
Our namesake species, the Joshua tree, has and will continue to feel the stress of hotter temperatures and drought conditions. At lower, warmer elevations, fewer seedlings are sprouting, growing, and surviving. By 2099 under the highest emissions scenario forecasted, the average annual temperature inside the park could increase by 8℉ (5℃). Research suggests that under these conditions, it could eliminate nearly all suitable habitat for Joshua trees in the park and reduce habitat in the Southwest by 90 percent. Even with lower emission scenarios, nearly 80 percent of suitable habitat in Joshua Tree could be lost. Check out the links at the bottom of the page for more information on this research.
A Crossroads for Species
The changing climate also affects many of our animal species. Most evolved to survive in a hot, arid environment. However, they will now be forced to adapt, migrate, or perish. Desert bighorn sheep will lose lower elevation habitat and will need to migrate to higher and higher elevations. This will likely cause more genetic isolation than bighorn populations already face and could lead to them not being able to live in the park. The desert tortoise population has already plummeted due to habitat loss, disease, raven predation, and climate change. Scientific research suggests that an increase of 5℉ (3℃) could leave 80 percent of the park uninhabitable for them. Additionally, four reptile species could lose half of their suitable habitat: Blainville’s horned lizard, desert spiny lizard, night lizard, and northwestern fence lizard.
Declining Bird Populations
Bird populations across Joshua Tree and the Mojave Desert have been in sharp decline over the past century. This has been driven largely by climate change and the loss of habitat. Climate change causes desert regions to warm and dry more rapidly than other ecosystems across the US. Many bird species in the desert are already at the edge of their physiological limits and the reduction of surface water has been a major factor in their decline. Surveys conducted by UC Berkeley between 1908-1968 and 2013-2016 show bird species declined 43 percent in the Mojave Desert. In the lower 48 US states, winter bird ranges shifted 19 miles(30 kilometers) north between 1975 and 2004.
The park has also become increasingly prone to wildfires due to warmer conditions. This problem has been made worse by the introduction of invasive plant species like red brome, a grass type that is able to quickly spread fire across the desert. If an area with Joshua trees burns through, most will not survive and reproduction in that area is made more difficult. Wildfires could also result in the loss of irreplaceable resources in the park, like historic structures and cultural artifacts.
Impacts on Visitors
The causes and effects of climate change impose negative impacts on visitors. Joshua Tree suffers from air pollution and smog blowing into the park. Increased warming from climate change worsens the visibility from smog and air pollution, due to the chemistry of how smog reacts to heat. On an average day, visibility is reduced from 160 miles to 100 miles (257 kilometers to 161 kilometers). On a high pollution day, visibility is reduced to 55 miles (89 kilometers). This not only affects our views, it also affects soils, surface waters, plants, and human health. Smoke from regional, climate-fueled wildfires adds to poor air quality and creates a health hazard. Excessive heat contributes to heat-related illnesses and dehydration. With a hotter, drier climate, the changes to our biodiversity could lead to less wildlife sightings, fewer annual wildflowers, and far fewer Joshua trees dotting the landscape.
Planning for a Changing World
The National Park Service has long tried to preserve the natural resources within its treasured parks. However, park managers now recognize that they may not be able to save all resources and species that are currently threatened. This has led to many hard decisions and deliberate planning to figure out what to prioritize saving. One way we are planning for the future is identifying and protecting Joshua tree "refugias". These are areas with higher elevations and more annual rainfall where Joshua Trees may be able to survive in a hotter and drier future. We have initiated fuels reduction projects in some of these areas to remove invasive plant species along dirt roads to create larger fire breaks that will act as a buffer to potential wildfires. Learn more about how the National Park Service is planning for a changing climate.
Collaboration is Key
Joshua Tree National Park is collaborating with researchers to understand the effects that climate change has had and will have on species of plants and animals in the park. The Joshua Tree Climate Change Collaborative is a team of researchers from UC-Riverside Center for Conservation Biology and Joshua Tree National Park created to monitor these effects in the park. This collaboration has produced multiple scientific journal articles describing the issue and effects to the park’s natural resources.
A Brighter Future
The good news is there is still time to make a difference. We can prevent the most catastrophic consequences if we choose to drastically reduce our greenhouse gas emissions. It will require bold changes to how humans live on planet earth. This can be accomplished in many ways:
Will you help be part of the change?
Last updated: October 28, 2021