Explorers in the late 1800s were drawn to the North Pole. It wasn’t that far away from western civilization. The northern parts of Canada, Greenland, Norway, and Russia had all been visited and at least roughly mapped. But the North Pole itself was a big mystery. Was it land? Sea? No one had ever reached the pole, so no one knew. The voyage defeated explorers again and again because the sea ice grew and shrank and shifted. As weather conditions changed, sea ice could pile up on top of itself, making ridges and ice quakes. The grip of this ice could grind ships to pieces. The USS Jeanette suffered a typical fate in 1881, becoming trapped in sea ice for months just off the northern coast of Siberia. As the weather cooled, and molecules of sea water locked on to the bottom of the ice lattice at the sea surface, the expanding ice gripped the hull. After months of ice growing and shrinking, squeezing then releasing the ship, the USS Jeanette succumbed and was crushed. Explorers who made it off their vessels on to solid ice faced different perils: The ice could melt and open up huge canals, impassable except with a boat. From any of the countries around the Arctic Circle it was hundreds of miles to the Pole, and the shifting ice was a formidable obstacle.
Three years after she sank, unmistakable wreckage from the USS Jeanette washed up near Greenland. It was an astonishing find because the wreckage had crossed the entire Arctic, right from one side to the other. Oceanographers wondered whether there was a current that left the coast of Siberia, traveled across the North Pole, and carried on to Greenland. And a young Norwegian scientist called Fridtjof Nansen had a wild idea. If he could make a ship that would withstand the ice, he could take it to Siberia and freeze it into the ice where the USS Jean- ette had sunk, and maybe three years later he’d pop out in Greenland. But crucially, on the way, he might pass over the top of the North Pole. No trekking, no sailing . . . just let the ice and the wind do the work for you. The only problem would be the wait. Nansen’s reward for this idea was to be both hailed as a genius and derided as a madman. But he was going anyway. He raised the money and employed one of the best naval architects of the age, because the ship itself would have to be like no other ship ever floated on the ocean. And so the Fram was made.
The difficulty was that as water freezes, the water molecules must take their places in their rigid lattice. If the temperature sinks low enough, they will stick. And if there isn’t enough room to sit in their proper place, they’ll push outward on everything nearby in order to make space. Any ship frozen into the ice suffered because growing ice took up more and more space, forcing itself outward. No known ship could resist that pressure, and no one knew how thick the ice would get in the middle of the Arctic. The Fram solved the problem in a brilliantly simple way. She was made to be chubby and round, only 128 feet long and 36 feet wide. She had a smooth curvy hull, almost no keel, and engines and rudder that could be lifted right out of the water. When the ice came, the Fram became a floating bowl. And if you squeeze a curved shape like a bowl or a cylinder from below, it will pop upward. If the squeeze from the ice got too much, the Fram would just be pushed upward to sit on top of it—or so went the theory. She was made from wood that was over 3 feet thick in places, and insulated to keep the crew warm. And in June 1893, she left Norway with tremendous public support and a crew of thirteen, rolling her way around the northern coast of Russia until she reached the place where the Jeanette had sunk. In September, she saw ice close to 78°N, and not long after that she was surrounded. As the ice first trapped her, she creaked and groaned, but as it expanded around her she rose, shifting upward exactly as expected. Frozen in, she was on her way.
For the next three years, the Fram floated with the sea ice, drifting northward at an agonizingly slow 1 mile a day. Sometimes she went backward or around in circles. The fickle freezing ice squeezed and released her, and she rose and fell in response. Nansen kept his crew occupied with scientific measurements, but got increasingly frustrated with the slow progress. When the Fram reached 84°N, it was apparent that she was not going to get to the pole, 410 nautical miles away. Nansen took a companion and left the ship, skiing over the ice in an attempt to go where his ship couldn’t. He set a new record for the farthest north anyone had been, but his best was still 4° short of the pole. He carried on across the Arctic toward Norway, meeting a fellow explorer on Franz Josef Land in 1896. The Fram and her remaining eleven crew stayed the course, carried by the ice to 85.5°N, only a few miles south of Nansen’s new record. On June 13, 1896, she popped out of the ice just north of Spitsbergen, exactly as originally planned.
Even though the Fram never reached the pole, the scientific measurements taken during her journey were invaluable. Now we knew for sure that the Arctic was an ocean and not a land, that the North Pole was hidden beneath ever-shifting sea ice, and that there really was a current that crossed the Arctic between Russia and Greenland. The Fram went on to carry men on two other great trips. The first was a four-year mapping expedition to the Canadian Arctic. And then in 1910 she carried Amundsen and his men to Antarctica, where they would beat Captain Scott to the South Pole. Today, she sits in her own museum in Oslo, lauded as the greatest symbol of Norwegian polar exploration. Instead of fighting the inexorable expansion of the ice, she had used it to ride across the top of the world.
The expansion of ice as it freezes is so familiar to us that we don’t really notice it. Put an ice cube in your drink and it floats—that’s just the way things work. But there’s an easy way to see that the frozen water really is the same stuff, just taking up more space. If you put some water in a transparent glass and add some largish lumps of ice, the ice floats so that most of it is below the surface but about 10 percent sticks up above the liquid level. You can mark the liquid level on the outside of the glass with a marker pen. The question is this: As the ice melts, will the water level go up or down? Once it’s melted, all those water molecules that are now sticking up above the water level will have to join the rest of the drink. Does this mean that the water level will rise? This is proper cocktail party physics, if you’re patient enough (or bored enough) at a party to spend time watching ice melt.
The answer is straightforward, and you should test it for yourself if you don’t believe me. The water level will stay in exactly the same place. Once the molecules in the ice become liquid again, they can fit together more closely. This means that they’ll fit perfectly in the hole that the submerged part of the ice was taking up. That bit of the ice cube that’s sticking up above the water line is exactly the size of the extra volume that the ice cube has because it expanded as it froze. You can’t see the atoms themselves in their lattice, but you can directly see the extra space they need when frozen.?