How Catastrophic Flooding Threatens Our National Parks

In June 2022, nature let loose with five inches of rain over just three days in and around Yellowstone National Park, rapidly melting the snowpack that had remained from winter. As the rain and meltwater poured into creeks and rivers, it became a severe flood that could not be absorbed by the already saturated soil.

The Yellowstone River reached its highest water levels recorded since monitoring started, cresting at 13.88 feet on June 13, 2022, breaking the previous record of 11.5 feet set on June 14, 1918. The powerful flooding from a record river discharge of 51,400 cubic feet per second damaged bridges, roads, cabins and utilities and forced more than 10,000 people to evacuate our oldest national park. 

Sadly, floods are the most common natural disasters in the United States, occurring in every state and nearly every county. And as global warming continues to cause sea levels to rise and to create extreme weather conditions, floodplains are expected to increase by about 45% by the end of the century—creating some distressing possibilities for the future of our natural landscapes. 

What Causes Catastrophic Flooding—and What Role Does Climate Change Play?

It’s tricky to directly correlate the damage in Yellowstone with climate change. Historically, rivers have been known to flood. But scientists are concerned that in the coming years, destruction related to changes in climate will realistically impact nearly all 423 national parks, many of which are particularly vulnerable to rising temperatures. Because so many national parks are situated at high elevations, they are being disproportionately affected by global warming. In a 2018 study, scientists found that average temperatures in national parks are rising at twice the rate experienced in the United States as a whole.

The Intergovernmental Panel on Climate Change notes that climate change “has detectably influenced” several of the water-related variables that contribute to floods, such as rainfall and snowmelt. Basically, while a warming world might not always directly induce floods, it instigates many of the factors that do.

For instance, large amounts of rain can increase the likelihood of flooding, and more heavy precipitation over the long term is an expected and observed consequence of climate change. That’s because a warmer atmosphere can hold more moisture, meaning more precipitation. The amount of water vapor that the atmosphere can contain increases by about 7% for every 1.8°F increase in atmospheric temperature.

Geography can also determine whether an area is likely to flood. Areas close to rivers are often at higher risk for floods. Being located on or near mountains or steep hills can also increase an area’s flood risk, as rain or snowmelt descending the terrain can cause streams and rivers to rise quickly. If a storm lingers over a mountain, a creek that’s usually only 6 inches deep can swell to 10 feet deep in less than an hour!

In colder areas, especially mountainous or high-latitude regions, climate change affects flooding in additional ways. Many of the largest historical floods have been from snowmelt, but with warmer winters due to climate change, less winter precipitation is falling as snow and more is falling as rain. While snow typically melts slowly in the late spring or summer, rain creates runoff that flows to rivers much more rapidly. And research shows that rain-caused floods can be much larger than snowmelt-only floods. When rain falls on top of snow, as happened during the recent flooding in Yellowstone, the combination can lead to especially high runoff and flooding.

With flooding comes issues of contamination and disease. Floodwaters can carry with them raw sewage, leaked toxic chemicals and runoff from hazardous waste sites and factory farms. They can pollute drinking water stores and cause eye, ear, skin and gastrointestinal infections—not just in humans, but in wildlife as well. When floodwaters recede, bacteria and mold may remain in quantities difficult for nature (or humans) to rebalance. 

Why Are Our National Parks Especially at Risk From Climate Change?

“Every single one of our more than 400 national parks [is] suffering,” says Stephanie Kodish, the director of the climate change program at the National Parks Conservation Association, a nonprofit and nonpartisan advocacy group. Here are just a few examples of some of our treasured National Parks that are at risk from climate change:

Because Everglades National Park sits at such a low elevation (just zero to eight feet above sea level), the potential for flooding caused by rising ocean levels could push native wildlife that cannot survive in salt water out of the area. Also, the salinization of groundwater puts tropical orchids at risk. 

Increasing heat is a massive problem in Joshua Tree National Park, and scientists are sadly reckoning with a future where the park might not even be a suitable habitat for the trees it was named after. Rising temps supported a blaze in the nearby Mojave National Preserve in 2020 that killed 1.3 million trees, causing the park management to call one major area “a graveyard of Joshua tree skeletons.”

The correlation of wildfires and floods is not to be underestimated. Burned areas are more susceptible to mudslides and debris flows during extreme rain, both because of the lack of vegetation to hold soil in place and changes to the soil structure itself caused by the fire.

Rocky Mountain National Park has seen a 3.4° increase in average annual temperature over the past century, which translates to shorter winters and less water availability for plants and wildlife in the summer. Meanwhile, rangers in nearby Glacier National Park in Montana have cause for concern that if the current weather patterns keep up, the park will have no glaciers left.

The United States Geological Survey Northern Rocky Mountain center recently released the Greater Yellowstone Climate Assessment in collaboration with scientists, resource managers and tribal communities from Wyoming, Montana and Idaho. According to the data projections, if future greenhouse gas emissions are not mitigated, the area will be subject to 40‒60 more days per year exceeding 90℉, which could diminish 40% percent of the Greater Yellowstone’s wetlands.

What’s Being Done to Save Our National Parks?

The National Park Service recognizes that our natural wonders are increasingly vulnerable as climate change instigates weather events that are more and more extreme. The NPS is experimenting with different ways of adapting, and the federal infrastructure bill passed last year has $1.7 billion allocated for national parks, which includes money for climate mitigation projects like relocating trails away from flood zones.

Other efforts include Glacier National Park biologists relocating bull trout to cooler waters and staff members in Joshua Tree National Park clearing out brush and invasive species from cooler or wetter areas that may be better able to sustain Joshua trees. In Yosemite, rangers are actively thinning forests to reduce the risk of wildfire.

At Nat Hab, we are all too aware that travel-related activities account for approximately 10% percent of worldwide greenhouse gas emissions that contribute to climate change. That’s why we created our carbon pollution reduction program and became the world’s first 100% carbon-neutral travel company. We partnered with Sustainable Travel International to reduce and offset our the carbon emissions generated from all of our office- and trip-related activities.

In 2019, we stepped our efforts up even further to offset all our 8,000 annual travelers’ flights to and from our global adventure destinations, increasing the total amount of carbon we offset by up to 400%. We may not be able to change the entire world, but we are doing everything we can to protect the natural landscapes that we love to share with you!