The Ozone crisis was one of the issues that got me interested in Geography, during the 1980’s it was a key issue, before any mention of global warming.
So what is the Ozone layer and why is it important? Basically the Ozone layer is a part of the atmosphere that filters U.V. radiation. Ozone is made up of oxygen atoms, three instead of the usually two. In this form it is highly unstable and susceptible to damage from chemicals such as CFC’s.
During the 1980’s the alarm was raised that the Ozone layer was thinning, due to human influence. CFC’s present in household items, such as spray cans and fridge freezers, were being released into the atmosphere, encouraging the break up of ozone, leading to Ozone depletion. International Agreement lead to the phasing out of these chemicals. Boys, check the back of your Lynx cans, it should say CFC free!
Ozone is important because U.V. radiation damages both plant and animal cells, in humans this may lead to skin cancer. U.V. radiation also limits the growth of plankton, the basis of life in the oceans.
Why are the holes over the poles? A bit complicated I’m afraid… During Antarctica’s winter, winds spiral towards Antarctica, dragging pollutants from elsewhere around the globe, the low winter temperatures create a kind of cap over Antarctica, called a polar vortex, little can leave, resulting in the concentration of pollutants increasing.
During Antarctica’s winter, special clouds also form high in the atmosphere, called Polar Stratospheric Clouds, even though the air is cold and there is little moisture. These clouds contain a high concentration of ice and nitrates, another ozone destroying chemical.
Because Ozone creation needs U.V. light, the Ozone level during winter in Antarctica is very stable, remember there is little radiation due to tilt of the Earth away from the Sun.
But as the temperatures warm in early spring, the U.V. radiation causes the process of Ozone creation and destruction to begin, but the high levels of pollutants, or Ozone depleting chemicals, results in more destruction than creation.
As summer comes, the polar vortex ends, as a result the Ozone depleting chemicals are redistributed, resulting in the Ozone layer recovering. I think anyway! 😉
Do we need to worry about this larger hole? Apparently not, the ‘hole’ is not really a hole but an area of Ozone depletion, even though the hole is larger, the concentration of Ozone continues to increase year by year, a testament to how international agreement can be used to tackle environmental problems. Scientists believe Ozone layers will be back to normal levels by 2065.
Not time to give up on sunscreen yet, but another challenge of working in Antarctica!
So nothing to worry about up North?
The blue shows depleted Ozone levels…
There is a great NASA website, with background information, images and videos about the Ozone layer.
For those with Google Earth, I have a comprehensive overlay of Ozone levels over time. I have adapted it slightly to just show the 2005 data, you can click on the overlay for each month, this allows you to see how the ‘hole’ in the Ozone layer changes during the course of the year from North to South. Have fun!