We've seen climate-caused sea level rises, record-breaking heatwaves, and devastating droughts. Now, it appears climate change is threatening an altogether shittier problem – quite literally.

The National Park Service (NPS) is having to prepare for an avalanche of human poop as the icy surface of Mount Denali melts and exposes 60 tonnes (66 tons) of excrement left by generations of climbers. This is a process, they say, that could start as early as this summer. 

Five hours to the north of Anchorage, Alaska, Mount Denali is America's tallest mountain. As one of the world's seven summits, it has attracted intrepid explorers from across the globe, keen to show off their Bear Grylls-esque skills and hardman credentials. Somewhere in the region of 1,200 climbers attempt the challenge every year, producing close to 2 tonnes (2.2 tons) of feces – which is equivalent in weight to a rhino.  

Historically, this human poop would be dumped in snow pits along the most common route up the Kahiltna glacier or, at higher elevations, chucked into deep crevasses. The thinking went that the excrement would get ground up in the ice, but this turns out not to be the case.

The good news is that, increasingly, people are taking responsibility for their own waste. Using small, lightweight cans with the capacity to hold 1.8 gallons of solid waste, climbers can carry it off the mountain. The NPS shored up this trend last year, introducing new rules requiring climbers to remove all waste from the mountain at elevations below 4,300 meters (14,000 feet). 

"Climbers and particularly guide services are really embracing the new policy and are even exceeding it," Michael Loso, a National Park Service glaciologist, told USA Today.

"It has become kind of an informal badge of merit to carry off all your waste."

Of course, this still leaves the problem of the 60 tonnes of human excrement that has accumulated over the years. Loso's research shows that the discarded feces can and do eventually pop up again downstream in areas where the surface of the glacier starts to melt. This is not only gross. It can be a health issue as the pathogens found in poop can survive decades after being buried in snow or flung into a crevasse.

"The waste will emerge at the surface not very different from when it was buried," Loso explained.

"It will be smushed and have been frozen and be really wet. It will be biologically active, so the E. coli that was in the waste when it was buried will be alive and well. We expect it to still smell bad and look bad."

This problem of human poo is getting more urgent as climate change accelerates the process of glacial melt. In the last 50 years, the Alaskan parks have lost 8 percent of their ice cover, USA Today reports. While a study published only last year discovered that temperature rise has seen the Denali glaciers thaw at rates not witnessed for at least 400 years. 

"We have lost more glacier cover in the Alaskan national parks than there is area in the whole state of Rhode Island," said Loso.

All of which means we could start seeing waste deposited at the lowest levels emerging as soon as the next climbing season, starting April. Charming.

[H/T: USA Today]