The world's insurance policy
So the first batch of the world's crop seeds is now packed away deep in the cold Svalbard mountainside, and the vault's doors, for the time being, are once again sealed. In total, more than 100 million seeds, representing some 250,000 individual strains of almost 100 major crops, from sorghum to sunflowers, have been loaded up in vault number 2 (I'm not sure why they started with vault no. 2 - although it may have been something to do with the fact that during the opening, vault no. 1 was playing host to 150 delegates and about a dozen live musical performers). Over 11 tonnes of seeds, in an impressive 656 boxes, were loaded up and locked away in little more than an hour.
So what now for the Global Seed Vault? Eventually, the collection will grow until it includes almost every crop strain in existence - as many as 1.5 million different seed types. Assembling this collection will mean taking delivery of millions upon millions of seeds, all carefully selected by the local and national seed banks that own them.
And then what? Well, in an ideal world, nothing. The Svalbard seeds will just sit tight in this natural deep-freeze, and stay undisturbed and ungerminated in the Arctic. Cary Fowler, the main driving force behind the seed vault's construction, likens it to an insurance policy for the world's food security. And insurance policies are among the few things that you buy but hope never to have to use.
But of course, this isn't an ideal world. Fowler, executive director of the Global Crop Diversity Trust, says: "if we had built this vault ten years ago we would have used it ten times already, for some major disasters - for the loss of the gene banks in Iraq and Afghanistan", for example. And it's not just the apocalyptic events - crop diversity is "going out with a whimper, not with a bang, in most cases", he adds. Floods, power cuts, equipment failure - all can cause seed banks in poorer countries to lose their precious seeds. "Doomsday is every day," Fowler says.
The seed bank will therefore be available for governments to call upon to bolster their collections of maize, rice, wheat, or anything they require. And the vault is set to last in perpetuity. Even if climate change wreaks huge changes on Svalbard's landscape, the conditions inside the mountain should still be good for seed storage for centuries to come. Even in 500 years, it might not still be naturally frozen, "but it will be naturally insulated", Fowler says.
As for Svalbard itself, scientists here have already got their eye on the next challenge. Geophysicists at the University Centre in Svalbard (UNIS) are aiming to make the entire island carbon-neutral by 2025 - ironic given that Svalbard's first settlers were coal-miners, and Longyearbyen is home to Norway's only coal-fired power plant (indeed, the Norwegian government has decreed that only three industries are allowed on Svalbard: mining, tourism, and scientific research; the government has been storing its own seed collections in a disused coal mine here for decades).
The brainchild of UNIS's Alvar Braathen, the project will first see the construction of a reserve power plant, designed to run on biofuels and sheduled for completion next year. After that, the main power plant will be given a scrub and converted so that the carbon dioxide it pumps out can be deposited back in the bedrock where the coal first came from. Finally, by 2025, the project's leaders aim to have all Svalbard's cars - and its many, many snow scooters - running on hydrogen fuel.
True, it doesn't sound all that hard when you consider that Svalbard is a virtual wilderness with only 2,000 people. But Svalbard, with its pristine beauty, and its toe-numbing, cold-headache-inducing climate, is one of the places with the most to lose from global warming. And the forward-looking attitude of its scientists is one of the things that made it the ideal place for the global seed vault in the first place.

I was excited to get the chance to cover the seed vault's opening ceremony - involving the placing of seed samples representing more than a quarter of a million crop strains onto the facility's shelves. What I didn't expect was that I would be expected to help.
As we arrived for the official ceremony and were ushered inside the entrance to the tunnel, everyone was given a box containing seed samples to carry down to the vaults themselves. As I dropped mine off I was handed a ticket informing me that I had just delivered a consignment of mung bean strains from India. It was surreal moment, thinking about Indian agriculture while painfully aware that the temperature was around 10 degrees below zero (later on, while performing some more conventional journalistic duties, the ink in my ballpoint pen froze while I was trying to take a quote from a Kenyan environmentalist. I reflected that she probably felt even colder than I did).
The opening itself was a more glitzy affair than your typical scientific get-together, featuring presidents, prime ministers and Norwegian TV stars. European Union president Jose Manuel Barroso described the vault as a "frozen garden of Eden". We then watched some footage of the seeds being placed on the shelves, on a giant screen made of polished blocks of ice.
Longyearbyen, on the remote Norwegian archipelago of Svalbard, is most northerly place you can get to on a commercial flight. If you're brave (or foolish) enough to want to go trekking to the North Pole (about 1,000 kilometres away), you have to go through here. But I'm not doing that - I've come here to watch the first seeds being put into a mountain bunker, with the aim of providing a backup copy of almost every crop there is.