'Disgusting' amount of rubbish and human waste left behind on K2, world's second-highest mountain

The most difficult-to-reach mountains on Earth are being polluted by humans.

At first it was the alarming levels of rubbish accumulating on Everest, the highest peak in the world, that captured headlines.

Now it's the "disgusting" amount of human waste and climbing gear left behind on K2, the second-highest summit on the planet, causing mountain climbers' concern.

READ MORE: Indian climber reaches top of Everest, six years after faking it

US climber Sarah Strattan said she was shocked by the garbage she encountered on K2 this year, where trails of debris and litter stretched "along almost the entire route".

Not only was the rubbish a terrible eye-sore, she said, it is now a climbing hazard.

"Camps 1 and 2 are disgusting," she wrote on Instagram.

"Waste from past and present expeditions has piled up everywhere."

Climbers were simply camping "right on top" of old gear, excrement, tents, used food packaging and fuel cans, she said.

Higher camps 3 and 4, situated at 7162m and 7620m, were "a little better but not pristine".

Strattan said rubbish littered the climbing route from advanced base camp all the way to K2's 8611m summit.

"Besides the camps, there are endless heaps and strands of old and destroyed fixed line ropes from current and past expeditions.

"Not only is this dangerous as it makes choosing the correct rope to use to climb up or rappel down sometimes impossible, but it's also a form of trash on the mountain."

Peruvian climber Flor Cuenca, who summited K2 on July 27, called the mountain in Pakistan's Karakoram range a "pigsty" and blamed big climbing companies for the mess.

"We are supposed to be mountaineers, why do we do this to the mountain?" she posted on Instagram.

"Isn't it that we go to the mountains to enjoy pure nature, solitude, the magic of the mountains?

"What do we think? That all this waste is going to disappear as if by magic or will the aliens be in charge of cleaning it up?"

READ MORE: Teen becomes youngest Australian in history to climb Everest

K2's predicament follows news in June that Nepal is preparing to move its Everest base camp because global warming and human activity are making it unsafe.

The camp is situated on the rapidly thinning Khumbu glacier, and the presence of so many people – around 1500 every climbing season – is also contributing to the problem.

People urinate around 4000 litres at base camp every day, according to a committee which recommended the move.

READ MORE: Glacier fears could prompt major Mt Everest change

Massive amounts of fuel burned for cooking and warming were also impacting the glacier.

In 2019, an American explorer found a plastic bag and lolly wrappers at the bottom of the deepest place in the ocean, the Pacific Ocean's Mariana Trench.

Researchers have detected high levels of microplastics in the 11km-deep trench.