Mount Everest has a feces problem.

Each year, hundreds of people attempt to climb the world's tallest mountain, spending weeks at four camps en route to adjust to the low levels of oxygen in the air. It's now estimated that they leave behind up to 26,500 pounds of excrement annually — and it's getting to the point where the pits of poop and urine surrounding these camps are becoming a serious environmental and health problem.

"It is a health hazard and the issue needs to be addressed," Dawa Steven Sherpa, an Everest expedition leader since 2008, told the AP Tuesday.

In a 2013 article in United Nations University's magazine, professor Pablo Figueroa put it this way:

Given the lack of an efficient solid waste management system, for decades expedition members emptied their bowels wherever they could when they had the urge. As a result, human feces have accumulated in the snow, and streams of excrement are periodically regurgitated by the glaciers up in the mountain.

It might seem odd that feces from hundreds of people is befouling one of the world's most remote places. But it's actually part of a bigger problem that has been growing for some time.

Mount Everest has become an overcrowded, polluted tourist destination

Over the last few decades, the number of people attempting Everest each year has skyrocketed. More than 700 foreigners attempted the climb in 2013, joined by hundreds of Nepali sherpas.

As National Geographic notes, it's easier to climb Everest than ever: many of these people have no previous climbing experience, and simply pay tens or hundreds of thousands of dollars to expedition operators to ensure they make it up the mountain.

These hundreds of climbers are funneled along two standard routes — so even though the mountain is enormous, their environmental impact is localized. At the four camps and the routes in between them, these climbers leave behind piles of broken equipment, used-up oxygen canisters, other garbage...and, as noted, lots and lots of feces. One study found that one of two water sources at Gorakshep, a village at 16,942 feet, near Mount Everest's base camp, was contaminated from all the feces runoff.

In addition, there are an estimated 200 frozen corpses on Everest — the bodies of unfortunate souls who perished en route, and couldn't be carried back down by their teammates. Most climbers report stepping over or around a frozen corpse at some point during their climb.

How to clean up Mount Everest

The trash problem — especially the growing piles of empty oxygen canisters — was first noted decades ago. Recalling his 1996 climb up Mount Everest in the book Into Thin Air, for instance, Jon Krakauer described how "the tents of Camp Four squatted on a patch of barren ground surrounded by more than a thousand discarded oxygen canisters."

During that era, several expedition companies instituted a program that paid sherpas for every empty canister they brought back down the mountain, which helped improve the situation. More recently, groups like the Eco Everest Expedition and Everest Summiteers Association began carrying out voluntary trash cleanups, collecting tons of trash annually.

Still, there are an estimated 10 tons of garbage left on Everest. Starting in 2014, the Nepali government began requiring all climbers to collect 17.6 pounds of trash from the mountain, but it's unclear how strictly this was enforced.

And poop is another problem entirely. Some climbers and sherpas carry it down in plastic bags, but right now, they're in the minority. Engineers have discussed building a biodigester that could process the feces at base camp, but at this point, it's just an idea.

Conservation groups have suggested cutting down on the number of climbing permits issued annually. But for Nepal, that might be difficult: sale of the $11,000 permits injects about $3 million into the Nepal economy annually, on top of indirect revenue spent on sherpa teams and other expedition expenditures.

Further reading: Maxed out on Everest: How to fix the mess at the top of the world