SVALBARD — A cave 80 meters under a mountain looks like the entrance to a war bunker. Or a secret weapons factory. It could be the stuff of fiction: We almost expect Darth Vader to emerge from a wall. Or it could be the gate to an underworld that is populated with dwarfs and trolls — creatures that animate works like theLord of the Rings.

It's minus 6 degrees Celsius in the cave in this surreal location in the Norwegian archipelago of Svalbard. But there are no trolls running around. And there aren't many humans either. Instead, tucked inside a cool chamber, 27 meters long and 10 meters wide, vacuum-packed aluminum bags hold more than 850,000 species of crops.

Welcome to Svalbard Global Seed Vault — the largest seed bank on Earth. There's enough room here to hold the genetic material of 4.5 million species of cultivated crops. But there is no room for genetically modified plants: their storage is forbidden according to Norwegian laws. There's absolute silence in the mountain here except for the roar of two air-conditioning units.

Almost every country has brought copies of their seeds here. There are about 1750 databases like Svalbard around the world and they use this Norwegian facility to preserve the diversity of fruit, vegetable and cereal crops that humans have harvested over the last 10,000 years.

There are no security guards onsite at the seed bank. But in Longyearbyen, the administrative center of Svalbard, a security center supervises the facility with cameras, heat sensors and fire detectors. An unauthorized person can't come through the steel doors.

The seed vault is often described as a type of Noah's Ark, a last hope come Judgment Day — whether it's a potential World War III, a devastating tsunami or the impact of a comet.

Maria Haga, the executive director of the Global Crop Diversity Trust in Bonn, laughs when she hears this.

"A vault like this is not really conceived for such dramatic scenarios. The true catastrophe has already happened by the way. Since the beginning of the 20th century we have lost 90% of our plant diversity," she says.

In today's agriculture, farmers only use varieties that are resistant, economically viable and offer a high yield. For instance, there are 200,000 breeds of rice but only a fraction of them are grown in Asia, says Haga. The vault is a backup for them if something happens — not a far-fetched possibility. For instance, when militants took control of the Syrian city of Aleppo, scientists had to leave a seed bank behind when they escaped. Luckily, they were able to obtain duplicates from the Norwegian facility.

There are reasons other than war when this vault comes in handy: a broken cold storage unit or power failure could destroy a local seed bank. Each country owns the seeds it deposits at the facility and they can inspect or pick them up at any time. It takes only a call to Bonn to arrange a meeting. The "Black Box System" makes sure that only the depositor can access the seeds.

Storing seeds is free of charge, says Haga. Norway assumes the cost. Seeds from North Korea sit next to South Korea here, boxes from Ukraine shoulder those from Russia. There's no ranking or order of priority for these seeds, only one common goal — to preserve the world's biodiversity.

Svalbard's location is ideal because of the polar climate and its political status. Although the archipelago belongs to Norway, the Svalbard-treaty of 1920 guarantees it certain freedom.

The vault only accepts seeds that are vital for global food security and sustainable agriculture. Only varieties that are not already stored in the facility can make their way in.

The world population is estimated to increase by almost one billion people over the next decade, making the global population 8 billion. With the increase in population, the worldwide demand for food could skyrocket. Even today, it has grown difficult to produce enough food for everyone due to rising temperatures, floods and droughts as well as new parasites and plant diseases. Agriculture today faces existential challenges.

"We have to increase food production mainly through a richer harvest because we can't count on gaining new areas of arable land," says Haga. "The preservation of biodiversity in agriculture is a basic requirement for food security."

One of the biggest unknown variables in all of this is climate change. Nobody knows how exactly the rising temperature will affect crops. That's why scientists, who are exploring different plant species that can survive in extreme conditions, need specimens from the Norwegian vault. Even if the vault looks like one Darth Vader may be lurking in.