What are the forces that shape our planet and its atmosphere?
Until the ground-breaking theory of plate tectonics came along in the 1960s, no one could explain how the continents could possibly be drifting around under our feet. Meanwhile, above our heads, the atmosphere was changing – and we have only recently started to question why.
Magnetic hypothesis of ocean floor spreading (1963)
Fred Vine FRS, Drummond Matthews FRS
Vine and Matthews proved the radical notion of continental drift was really happening. They showed that the sea floor was spreading apart at mid-ocean ridges, continuously creating new ocean crust. The evidence, published in 1966, was in the magnetic signature of the volcanic rock that had emerged and cooled. Its symmetric pattern of stripes on either side of the ridge captured the periodic reversals in the Earth’s magnetic field over millions of years.
Plate tectonics (1966)
Dan McKenzie FRS
What forces could possibly be strong enough to shift the ground itself? McKenzie developed the theory of plate tectonics using the earlier ideas of continental drift. His mathematical models explained how the Earth’s mantle slowly churns through convection, as heat moves from the inside of the planet to the surface. The tectonic plates that make up the crust are carried along on top, constantly being created at some boundaries and destroyed at others.
Ozone depletion (1985)
James Lovelock FRS, Frank Sherwood Rowland ForMemRS
Today, we debate action on climate change, but in the 1980s it was far from mainstream. In 1985, Lovelock measured man-made CFCs in the atmosphere – chlorofluorocarbons used widely in fridges and aerosols. He discovered that nearly all those released since the 1930s were still around, drifting ever-higher. Rowland then showed that when they reached the stratosphere, CFCs would finally react in ultra-violet light to release chlorine, which damaged the ozone layer. When the British Antarctic Survey subsequently found the ozone hole above the South Pole, it spelt the end for CFCs – and the start of wider climate concerns.