26 August 2009
A few weeks back there was a riveting summary in NATURE, of the science surrounding the Ozone hole. Quirin Schiermeier tells the story of how we averted an environmental catastrophe in the absolute nick of time. It’s also a great example of how looking at unexpected observations in a logical way, can lead to a better knowledge of how the planet works.
First some background.
While most people have heard of the ozone hole, they get confused about whether it’s good or bad. They hear about high ozone levels in the daily air quality report , and then hear there is a hole in the ozone over the South Pole!
It’s easy to explain. Ozone near the ground is bad. It’s formed due to a chemical reaction between sunlight and the exhausts from internal combustion engines.
Ozone in the stratosphere is good. It blocks most of the dangerous UV rays produced by the sun, from reaching living organisms near the Earth’s surface. What little does get through, is responsible for that bad sunburn you got at the beach last Summer.
The first the world heard of the ozone problem was in 1985. It was a paper published in NATURE. Researchers had discovered that a very widely used class of chemicals called Chlorofluorocarbons (CFC’s) were destroying Ozone in the frigid stratosphere above Antarctica. The hole had already been detected by instruments, but was dismissed as bad data. Scientists monitoring the Ozone layer in Antarctica originally thought the drop on Ozone in the Austral spring was an instrument error.
How wrong they were.
If the discovery had been made 20 years later, it would have likely been too late to avoid a massive increase in skin cancers and perhaps a catastrophic damage to the atmosphere that protects us from the dangerous radiation just 20 miles above us. You would think those who discovered it would get a Nobel Prize.
What happened next is a great example of how the countries on this planet CAN work together when they have to. The Montreal Protocol in 1987 began a rapid phase out of CFC’s. There have been several follow up agreements that have strengthened the regulation of CFC’s. While the Ozone hole is still there, the amount of chlorine in the atmosphere is no longer climbing and the Ozone hole should begin closing around the middle of this century. It will not happen as quickly as thought a few years ago though, and this is where things get even more fascinating.
One of the predictions of global climate models is, that as greenhouse gases increase, the bottom of the atmosphere (the troposphere) will warm, while the stratosphere will get colder. This is certainly happening, and is yet another of the many separate verifications that the planetary warming is not natural. It’s unequivocally us.
Ozone actually warms the stratosphere when it absorbs ultra violet radiation. Over Antarctica, the lack of Ozone, is leading to an even colder stratosphere, and this may explain why Antarctica has been behaving somewhat differently than what was initially forecasted by global climate models.
The cooling stratosphere is causing more ozone to be depleted. There is now talk of a new treaty to strengthen the previous agreements and include stringent limits on the chemical Bromine. Why? Bromine is far more capable of destroying Ozone than CFC’s.
We may not be out of the woods just yet. The Ozone hole reached a new record low in 2006. The colder stratosphere is actually causing more destruction of Ozone, and many researchers believe the Ozone hole will recover more slowly than anticipated. Current thinking is that it may not recover until the 2060’s.
The colder stratosphere is having an affect on the ice shelves of Antarctica as well. The polar vortex, is a strong semi permanent low pressure center in Antarctica. It’s gotten stronger, as a result of the colder stratosphere. This in turn, has caused warmer air and ocean water to reach the Antarctic Peninsula, causing the rapid rise in temperatures observed there. The opposite is happening to the Ross Ice Shelf. The vortex is steering colder air over the Ross shelf, causing it to grow!
One of the most common claims to be found on junk science sites is that Antarctica is getting colder, and that this somehow means that all that science published on climate change is wrong. Ask yourself this: Does it makes sense that everything we have learned about climate is all wrong, because 1/12th of the planet, is not behaving like the rest?
That’s what they would have you believe on some of these silly junk science sites!
Instead, it’s much more logical to look for an explanation that fits with the science that has built up from the time of Svante Arrhenius, and John Tyndal to Roger Revelle, and James Hanson. The history of what we know, and how we know it is a great way to understand any field of Science.
There is an excellent book that does just that. It’s THE DISCOVERY OF GLOBAL WARMING by Spencer Weart. You can read it online for free.
It’s frightening to know just how close we came to destroying our ONLY protection from the harsh reality above our thin layer of air. As the Duke of Wellington said about the battle of Waterloo, It was a damn near run thing.
FIXING THE SKY- NATURE Quirin Schiermeier 13 Aug 2007