Since the mid‐1970s, an “ozone hole” has developed in the stratosphere over Antarctica each austral summer. The Arctic, by contrast, has been immune to such severe depletion because it is much less susceptible to developing a strong vortex, a pattern of winds that encircles the pole, isolating a continent‐sized body of air in which all the conditions for ozone depletion can be established. In March 1997, however, the Arctic stratosphere behaved more like its southern counterpart than had ever been observed before, and Arctic ozone levels hit record lows for March. (See the figures on page 19.) The observations were reported in eight papers in the 15 November 1997 issue of Geophysical Research Letters.