Update, Monday 3:07 p.m.: It turns out that the flood at the Svalbard Global Seed Vault in Norway first reported Friday by The Guardian happened in October, not last week. And it was caused by both rain and melting permafrost. A spokesperson for Statsbygg, the Norwegian operation that runs the seed vault, confirmed this to both CNN and Popular Science. “This fall—October 2016—we had extreme weather in Svalbard with high temperatures and a lot of rain—very unusual. This caused water intrusion into the tunnel leading to the seed vault,” the spokesperson told Popular Science.

Meltwater from thawing permafrost is concerning that high North in the Arctic. CNN reports that the seed vault officials are unsure if it will escalate in coming years, and are taking precautions. But officials confirmed today in a press release that, “Globally, the Seed Vault is, and will continue to be, the safest backup of crop diversity.”

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Deep underground in the far reaches of the arctic North, there’s a fortress that’s supposed to be one of humanity’s safeguards if we can’t feed ourselves in the future. It’s a vault containing more than 500 million seeds, representing 930,000 different crops, many of which can’t be found in fields today. It’s the ultimate failsafe if the world’s farms burn or diseases decimate our staples and we have to start over. The facility is supposed to keep these seeds safe for hundreds of years, without human oversight.

What the designers weren’t counting on so much: floods possibly linked to climate change.

The Guardian is reporting that a flood due to melting arctic permafrost breached the facility, creating an icy mess. The seeds are safe for now — they’re packaged in moisture-proof bags, and the flood didn’t reach the vault, just the entrance. Still, it caught the facility managers by surprise. The Guardian reports:

Soaring temperatures in the Arctic at the end of the world’s hottest ever recorded year led to melting and heavy rain, when light snow should have been falling. “It was not in our plans to think that the permafrost would not be there and that it would experience extreme weather like that,” said Hege Njaa Aschim, from the Norwegian government, which owns the vault.

Should we be alarmed? Maybe not. According to Popular Science, it turns out that there’s some water intrusion into the front of the facility most summers as seasonal meltwater creeps its way in. Popular Science also reports that the seed vault is a bit uphill from the entrance. So it would take much, much more water to overwhelm the seeds. In any case, it’s something to monitor. The amount of meltwater this season was unexpected. And in the arctic, that’s concerning.

The “doomsday” vault’s location — inside a mountain on a Norwegian archipelago — was chosen in part for its cold temperatures. They make refrigerating the seeds for long-term preservation easy, without the need for energy-consuming refrigerators. It can run — so its architects hoped — without human supervision.

Record-high temperatures in the region have thrown this dream into disarray.

Ironically, the facility was funded by the Norwegian government because of the threat of climate change. Climate change poses a huge threat to biodiversity and food production. And the seed vault ensures that these crops — and, more importantly, their genetics — will be preserved.

“This is a seed collection,” the American Scientist explained last year. “But more importantly it is a collection of the traits found within the seeds: the genes that give one variety resistance to a particular pest and another variety tolerance for hot, dry weather.” Plant breeders in the post-apocalypse can use this genetic repository to fashion plants tolerant to whatever hellscape remains.

Global temperatures are rising worldwide, and fastest at the poles, dramatically changing this inhospitable landscape. Permafrost that has not thawed in millennia is now melting, potentially releasing untold viruses and bacteria that have been trapped inside. It’s opening up shipping routes long closed off by ice.

Seed vault managers tell the Guardian they’re now taking precautions: ensuring the vault’s entrance is waterproof, and engineering trenches to drain more meltwater away from the facility.

But this incident goes to show: In the age of a rapidly changing climate, we can’t be so certain our failsafes won’t fail.