Buffeted by the Atlantic Ocean on one side and the Pacific on the other, the Mitre Peninsula, at the far southern tip of South America, is one of the coldest, harshest places on the planet. “It’s the end of the earth,” said Martina Sasso, program coordinator at Rewilding Argentina.

But this 2,400-square-kilometer slab is also a complex, carbon-rich wetland that holds 85% of all of Argentina’s peat. “The amazing part of this ecosystem, this great wetland, is that it is almost pristine,” Sasso told Mongabay.

These Patagonian peatlands are the main carbon sink outside of the tropics in the southern hemisphere, a largely unbroken, unspoiled “carpet” dominated by the cushion-forming perennial Astelia pumila, which creates a bog that can absorb carbon four and a half times faster than those dominated by sphagnum moss and sedges.

Peat forms in waterlogged, acidic conditions, as layer upon layer of decomposing vegetation slowly builds up. It can take 1,000 years to form just one meter of peat, the rotting organic matter locking in the carbon as the bog grows. In places on the peninsula the peat is 3m deep and it’s estimated that these mires contain 315 million metric tons of carbon, the equivalent of Argentina’s total emissions for three years.