There’s good news from Antarctica, where researchers with tools like ozonesondes — pictured above — have been following the infamous ozone hole as it waxes and wanes over the seasons. The ozone hole has shrunk by 1.5 million square miles – around 4 million square kilometers — and this “healing” trend appears to be continuing.A major ecological catastrophe has been averted, and we can cite human intervention as the reason. When the globe swept into action with 1987′s Montreal Protocol, which banned a number of substances known to contribute to ozone depletion, it apparently worked.When scientists first began to observe a hole in the ozone layer over Antarctica, it was a cause for grave concern. Though ozone levels actually fluctuate throughout the year, they perform an important function by blocking the sun’s harmful UV radiation.