A new study points to increased risks of heat-related illnesses in national parks due to climate change/NPS file

As climate change continues to drive higher and higher temperatures across the National Park System, Grand Canyon and other parks are going to become more and more dangerous as visitors in search of recreation, rejuvenation, and inspiration chance being stricken by a heat-related illness, according to a new study.

The research, published last week in the journal PLOS One, predicted that annual heat-related illnesses in Grand Canyon National Park could rise as much as 137 percent from 2004-2009 levels, to 254 cases per year by 2100. But "that assumption may also ultimately prove to be an underestimate because visitor numbers may increase further," the study added.

Some of those cases could lead to fatalities, as heat stroke and hyponatremia, in which you drink too much water for your body to handle and sodium levels in your blood are overly diluted, can lead to death.

National park visits often are associated with vacations, breaks from the day-to-day life. As a result, visitors run the risk of not being conditioned for the weather they encounter and activities they participate in.

"...the nature of people’s use of public lands also poses distinct climate change-related health risks because 1) visitors often engage in more strenuous exertion and experience greater exposure to the elements with fewer resources than experienced in daily life, and 2) these areas are increasingly experiencing unprecedented climate and weather conditions that may surprise experienced visitors and even park staff," reads a section of the latest research conducted by Danielle E. Buttke, Brinkley Raynor, and Gregor W. Schuurman.

The changing climate's impacts on the National Park System are varied, from the loss of glaciers and catastrophic fires to coral bleaching episodes, the rerouting of rivers, and the potential loss of such species as Joshua trees and wolverines that can't cope with the rising temperatures. Human visitors also need to appreciate the climate-changed environments they're entering.

In the case of Grand Canyon National Park, it's been no secret that the high temperatures, direct exposure to the sun, and challenging hiking trails carry risks.

"Heat is a killer, especially of the naive or ignorant," Michael P. Ghiglieri and Thomas M. Myers wrote in their 2001 book, Over The Edge: Death in Grand Canyon. "While descending most Canyon trails, the ease and coolness of the descent are seductive. It's a breeze even for the unfit or the unprepared. Until the time comes to hike back up. Then, when it's all too often a hot, dry, hard, agonizing, and often torturous physiological contrast to the descent, the unfit get weeded out late in the game and get weeded out brutally. Sometimes fatally."

Higher daily temperatures resulting from climate change raise the risks.

And the Grand Canyon doesn't hold a monopoly on deaths attributed to the heat. While a 57-year-old woman died last month in the park while on a backcountry trip that saw daily temperatures rise "well over 100 degrees," this summer's high heat has also led to deaths at Death Valley National Park (2) in California, Big Bend National Park (2) in Texas, and Arches National Park (1) in Utah.

While the new study focused on Grand Canyon National Park, the authors made clear the park's heat-related illnesses are not unique to that park.

"Excessive heat is responsible for more deaths than any other extreme weather event, and the frequency, intensity, and duration of extreme heat events are increasing globally due to climate change," they wrote. "Physical exertion, sudden exposure to excessive heat, and the lack of physical or behavioral adaptation resources are all associated with greater HRI risk, which is expected to increase for visitors to Grand Canyon National Park and other public lands as climate change worsens."

Indeed, at Yosemite National Park in California rangers last summer noted a number of heat-related illnesses suffered by hikers hoping to stand atop Half Dome.

"In one case, having successfully summited Half Dome in the early afternoon, and with only a mile or so left to reach the trailhead, a subject in his mid-20s was unable to continue hiking due to severe cramping in both legs. A search and rescue team responded up the Mist Trail and brought the patient to the trailhead in a wheeled litter," a blog by rangers read. "Meanwhile, to help with rehydration, the paramedic on scene gave the subject intravenous normal saline; by the time the team reached the trailhead his condition had improved dramatically. In another case, a subject in his early 70s experienced intense muscle cramping in his legs while on the summit of Half Dome. Bystanders descended the cables and reported his condition to the ranger checking permits at the base of Sub Dome. By the time the ranger arrived at the top of the Half Dome cables, fellow hikers had given the subject water mixed with electrolyte tablets, and the subject reported that his symptoms were improving."

Elsewhere in the park, there were three other incidents when rangers responded to hikers struggling in the heat, the blog noted.

Rangers at New River Gorge National Park and Preserve in West Virginia, a place not typically associated with heat-related illnesses, are working to develop approaches to dealing with the problem, the Grand Canyon study noted.

While Grand Canyon established a "preventive Search and Rescue" program in 1996 in an effort to alert visitors to dangers before they fell victim to them, the study raised the possibility that, "As temperatures rise and patterns of extreme heat become more variable, preventative SAR resources may not be ideally structured to address changing risk patterns nor increasing demand, and GCNP park EMS and preventative SAR services are again at risk of becoming overwhelmed by demand."

National Park Service staff at the Grand Canyon, Death Valley, Santa Monica Mountains National Recreation Area, and Saguaro National Park, just to name four units, tell hikers not to head out after 10 a.m. in summer and to be sure to carry lots of water and salty snacks. Whether rising temperatures will lead to closure of some areas during the summer remains to be seen.

Although the Park Service has worked hard on climate-change adaptation in its parks, "significant changes in important places and loss of access to many important resources may occur as the climate crisis worsens and recreation becomes less safe in these remote settings," the authors said.