For centuries, Europeans believed that the sea around the North Pole might be completely free of ice. This “open polar sea” haunted their imaginations, even appearing in the opening of Mary Shelley’s Frankenstein. The idea had important implications, because like the Northwest Passage, it promised a possible shortcut to Asia.
Explorers held out hope, even as they confronted icy northern waters. This might seem like wishful thinking, but Christopher Carter, a historian of geophysics, explains that for a brief time, the idea gained support in the scientific community. By the early nineteenth century, some scientists believed that discoveries in geomagnetism supported the existence of the open polar sea, writes Carter.
They were working at the confluence of new streams of scientific thought. A century earlier, Edmund Halley had sailed around the Atlantic, measuring compass deviation. He translated his observations onto a map, showing magnetic contour lines crossing the globe. In 1817, Alexander von Humboldt used similar contour lines to show global temperature variation. Humboldt and others were thinking about global phenomena, and about interconnectedness in nature. Then in 1820, Hans Christian Oersted saw an electrified wire move a compass needle, showing that electricity and magnetism were somehow connected.
Carter describes how Scottish scientist David Brewster tried to bring these ideas together. He suggested that geomagnetism and temperatures might also be connected. If so, the geographic North Pole might be warmer than expected. Brewster would need to find a link between heat and magnetism, and scientists in the 1820s tried to do just that.
In one experiment, Samuel Hunter Christie heated parts of a bismuth plate representing the Earth and measured changes in the magnetism of the plate.
“He found that heating one side of the plate would create a magnetic pole on the other side,” writes Carter. This seemed to support an idea from Halley that there were four magnetic poles on Earth. It also implied a connection between magnetic poles and temperature.
In fact, it suggested that the north magnetic pole might be the coldest place on Earth. “Since the magnetic pole was displaced from the geographic pole,” writes Carter, “the coldest point…would be away from the North Pole, allowing for an open polar sea.”
Direct observation eventually undermined the theory. Carter writes that temperatures recorded far from the magnetic pole were often much lower than those allowed for by the theory. Explorers continued attempts at the North Pole, running into ice at high latitudes. By the end of the century, they abandoned the open polar sea theory.
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However flawed the results, Carter believes this episode highlights a moment of pivotal change in the history of science. Brewster and Christie “followed the general trend of the age in seeing natural phenomena as part of a single whole,” he writes. The emerging studies of electromagnetism, geomagnetism, and meteorology all depended on this sort of insight.
Climate science likewise studies the connections between natural systems. Scientists predict that sometime in the near future, the Arctic may see its first ice-free day, transforming the open polar sea from myth into reality.
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