It’s over twenty years since the discovery of the ozone hole drew world attention to the impact of human activity on the global environment.
Scientists from British Antarctic Survey began monitoring ozone during the International Geophysical Year of 1957–58. In 1985 scientists discovered that since the mid 1970s ozone values over Halley and Faraday research stations had been steadily dropping when the sun reappeared each spring. Something in the stratosphere (about 20km above Earth) was destroying ozone.
Research shows that during the polar winter, clouds form in the Antarctic ozone layer and chemical reactions on the clouds activate ozone destroying substances.
When sunlight returns in the spring, these substances (mostly chlorine and bromine from compounds such as chlorofluorocarbons and halons) take part in efficient catalytic reactions that destroy ozone at around 1% per day.
This discovery changed the world.
A side effect of global warming is that the temperature of the ozone layer is falling slightly. This means that more of the clouds can form over Antarctica, and hence delay the recovery of the ozone hole. Elsewhere however the same cooling is likely to slightly thicken the ozone layer. The ozone hole can also help amplify global warming by changing where solar energy is absorbed in the atmosphere. Another link is that the ozone depleting chemicals are greenhouse gasses, so reducing their amount has significantly helped in combating climate change.
The ozone hole formed within less than a decade, and shows us just how sensitive our planet is to human activities. Other signals of the planet’s health, which today are just beginning to be detected, may develop equally rapidly. The long series of careful measurements obtained by the British Antarctic Survey show how important it is to have a good baseline from which to measure changes.
For more information checkout The Ozone Hole information leaflet!
