Natural Environment Blog

Satellite image of the ozone hole on 24th September, 2006.

You may have heard about the “ozone hole” that’s located somewhere above us, in the Earth’s atmosphere. You may also have heard that it’s not really a good thing for us here on Earth. If you’ve heard this, you heard right.

But what exactly is the ozone hole?

The ozone hole is an area of extremely depleted ozone in the ozone layer above the Antarctic. The ozone hole is not present all year round though. It only occurs during the beginning of the Southern Hemisphere spring - between August and October. 

The problem with the ozone hole is that, it allows harmful ultraviolet (UV) rays from the sun to reach Earth. These UV rays are usually filtered out by the ozone layer, but when the ozone has been depleted (as is the case with the ozone hole), the UV rays are no longer filtered out.

Why are UV Rays Harmful?

Although in small doses, UV light can be beneficial, overexposure can cause sunburn and some forms of skin cancer. Prolonged exposure to UV rays can also cause other problems for the skin, eyes and even the immune system.

UV rays don’t only affect humans. Studies have shown that hundreds of species of plants and animals display a negative reaction to increased UV rays. There are however, some species that react positively to an increased exposure to UV light.  

What Causes the Ozone Hole?

Here are the main factors that contribute to the ozone hole:

• Stratospheric sulfate aerosols - In other words, volcanic eruptions
• Stratospheric winds
• Greenhouse gases
• Sunspot cycle - an 11 year cycle that causes variation in the UV radiation produced by the sun
• Stratospheric chlorine - coming mainly from man-made halocarbons

While we generally have little control over natural occurrences, we do have control over the man-made ones. You may have heard that chlorofluorocarbons (CFC) are causing the ozone hole to grow bigger. CFCs are a group of chemical compounds that consist of alkalines such as methane or ethane. They also have one or more halogens linked, such as chlorine or fluorine.

CFCs find their way into the atmosphere from refrigeration and propellant devices and processes.

Basically, man-made products are contributing to the increasing size of the ozone hole.

What’s Being Done About It?

Many countries have banned the use of most CFC-emitting aerosol products, such as fly spray, deodorants, and hair spray. The bans generally require that those types of products are produced in a way that doesn’t result in CFCs being emitted.

Such a ban was introduced in the U.S. in 1978, and although most CFC-emitting products were banned long ago, there are still some that are being phased out. For example, albuterol metered dose inhalers (MDIs) will not be available in the U.S. after 31 December 2008.

There is also an international environmental treaty called the Montreal Protocol on Substances that Deplete the Ozone Layer. At present, 191 countries are involved in this agreement, which is designed to phase out substances that lead to ozone depletion. There is also a belief that, as long as the treaty is adhered to, the ozone layer will recover by 2050.

I just read that the ozone hole over the antarctic is bigger in 2008 than it was in 2007.

In 2008, the ozone hole expanded by 2 million square kilometers to 27 million square kilometers (or 10.4 million square miles). 

Despite it’s growth over the last year, the ozone hole still isn’t as large as it was in 2006, when it was the most severe ozone hole on record. Back then it reached 29 million square kilometers (11.2 million square miles) on September 24.

In case you’re wondering,  when it comes to the ozone hole, bigger is not better. The ozone protects us from ultraviolet rays that can increase our risk of cancer and harm marine life. The larger the ozone hole becomes, the worse it is for us on Earth.

Researchers have discovered giant marine life in the seas of the Antarctic.

The discovery was made during a 50 day voyage in the Ross Sea. New Zealand Marine Scientist, Don Robertson said that they found “Huge sea snails, jellyfish with tentacles up to four metres long and starfish the size of big food platters”.

The voyage, which covered 3,200 km, resulted in 30,000 specimens, making it the most comprehensive survey to date. Among the specimens, were about 90 different species of fish, eight of which could be a previously undiscovered species. There are at least eight new molluscs and a range of new invertebrates too. Analysis of all 30,000 specimens could take up to two years.

The survey covered all levels of the water, from the surface to the sea floor - 3,500 meters deep.

The survey is part of the International Polar Year program, which involves 23 countries and 10 other voyages around the Antarctic. The voyages will continue until July 2009.