LONGYEARBYEN, Norway — It’s been dubbed a Noah’s Ark for plant life and built to withstand an earthquake or a nuclear attack.

Dug deep into the permafrost of a remote Arctic mountain, the “doomsday” vault is designed by Norway to protect the world’s seeds from global catastrophe.

The Svalbard Global Seed Vault, a backup to the world’s 1,400 other seed banks, is expected to be officially inaugurated in a ceremony today on the northern rim of civilization attended by about 150 guests from 33 countries.

The frozen vault has the capacity to store 4.5 million seed samples from around the globe, shielding them from climate change, war, natural disasters, and other threats.

“There are not many countries in the world they could have pulled this off,” said Cary Fowler, executive director of the Global Crop Diversity Trust, a partner in the project.

Norway’s government owns the vault in Svalbard, a frigid archipelago 620 miles from the North Pole. The Nordic country paid $9.1 million for construction, which took less than a year. Other countries can deposit seeds for free and reserve the right to withdraw them upon need.

The operation is financed by the Global Crop Diversity Trust, which was founded by the United Nations Food and Agriculture Organization and Biodiversity International, a Rome-based research group.

European Commission president, Jose Manuel Barroso, 2004 Nobel Peace Prize winner, Wangari Maathai of Kenya, a Crop Diversity Trust board member, and Norwegian Prime Minister Stoltenberg planned to attend the opening ceremony 425 feet deep inside Plataaberget mountain.

It was about 5 degrees outside as reporters were allowed in yesterday for a sneak peak. But it was colder inside. Giant air conditioning units have chilled the vault to just below zero, a temperature at which experts say many seeds could survive for 1,000 years.

Inside the concrete entrance, decorated for the opening with an ice sculpture of a polar bear, a roughly 400-foot-long tunnel of steel and concrete leads to three separate 32-by-88-foot chambers where the seeds will be stored.

The first 600 boxes with 12 tons of seeds already have arrived from 20 seed banks around the world, Norwegian Agriculture minister, Terje Riis-Johansen, said. The first 75 boxes are to be carried into the vault by guests as part of the opening ceremony.

The seeds are packed in silvery foil packets — as many as 500 in each sample — and will be placed on blue and orange metal shelves inside the vault. Each chamber can hold 1.5 million packets holding all types of crop seeds, from carrots to wheat.

Construction leader, Magnus Bredeli-Tveiten, said the vault has been designed to withstand earthquakes — successfully tested by a 6.2-magnitude temblor off Svalbard last week — and even a direct nuclear strike.

And even if power fails and cuts off the air conditioning, the permafrost insulating the vault would help keep the seeds “cold for 200 years even in the worst case climate scenario,” Mr. Fowler said.

He expects the vault’s life span to rival that of Egypt’s ancient pyramids.

“So much of the value of Svalbard is that it is so far away from the dangers” that affect many other parts of the globe, Mr. Fowler said. The archipelago is about 300 miles north of the Norwegian mainland.

Other seed banks are in less protected areas. War wiped out seed banks in Iraq and Afghanistan, and one in the Philippines was flooded after a typhoon in 2006.

Mr. Fowler called the vault an insurance policy against the unthinkable. “It’s like you get in your car in the morning and drive to the office. You don’t expect to get into a car accident, but you buy insurance anyway.”