Stephen Leahy* - Tierramérica

TORONTO, Sep 13 2005 (IPS) — A huge ozone hole has developed over Antarctica for the second year running, exposing southern Argentina and Chile to high levels of damaging ultraviolet radiation from the Sun.

The “hole” over the South Pole – actually an annual thinning of the ozone layer during the southern hemisphere spring months of September and October – currently measures about 25 million square km and growing, according to European Space Agency satellite data, and it may yet become the biggest hole in history.

While this seems at odds with recent announcements that the amount of ozone-depleting chlorofluorocarbons (CFCs) in the lower atmosphere has finally started to decline, those chemicals will remain in the atmosphere for many decades.

Meanwhile, increases in other ozone-depleting substances like methyl bromide are rising and continued illegal use of CFCs means the fight to protect the ozone layer is far from over.

“New holes will likely develop for at least the next 30 to 40 years,” says Craig Long, a meteorologist with the U.S. National Oceanographic and Atmospheric Administration’s (NOAA) Climate Prediction Centre, located in the eastern state Maryland.

“This year’s Antarctic hole should reach its maximum size mid-September,” Long told Tierramérica. The timing coincides with the United Nation’s International Day for the Preservation of the Ozone Layer, September 16.

“Thanks to the Montreal Protocol on Substances that Deplete the Ozone Layer, the risk of harmful radiation appears to be receding,” said UN Secretary-General Kofi Annan in a statement.

The 1987 Montreal Protocol requires the 184 nations that signed it to phase out the use of CFCs and nearly 100 other chemicals that break down the three-oxygen ozone molecules in the Earth’s stratosphere. The ozone layer covers the entire planet at an altitude of around 15 to 30 km and protects living organisms from harmful ultraviolet (UV) rays.

Reduced ozone levels over the past few decades has increased UV exposure around the world, resulting in higher levels of skin cancer, eye disease and other health issues in humans and in many other species of animals and in plants.

But there was a levelling off of declining ozone levels globally between 1996 and 2002, according to a new study by the Centre for Integrating Statistical and Environmental Science at the University of Chicago.

While this is good news, scientists urged caution. “Some of these chemicals remain in the stratosphere for many decades, meaning that chemicals produced years ago will continue to be harmful for decades to come,” said Sherwood Rowland, in a statement.

Rowland and colleagues Mario Molina and Paul Crutzen won the 1995 Nobel Prize in Chemistry for their work identifying the threat to the ozone layer in the 1970s.

But there is concern because the Montreal Protocol allows the release of other ozone depleting substances for critical short-term use.

For example, methyl bromide was to have been completely phased out by Jan. 1, 2005. However, U.S. vegetable and fruit growers will use nearly 10 million kg (23 million pounds) of the chemical pesticide in 2005 – more than the country used in 2002.

The United States has convinced countries party to the Protocol to continue to allow some 8.5 million kg of methyl bromide in 2006, more than the rest of the industrialised world combined. Although there are alternatives, methyl bromide is cheap and easy to use.

Alternatives to CFCs, meanwhile, are in wide use throughout the world, but because they are more expensive there is a thriving black market trade for CFC use as refrigerants, fire suppressants and industrial solvents.

Millions of pounds of CFCs have been illegally imported into the United States. Though the problem may be on the decline there, it is “an emerging significant problem especially in Asia” according to UN Environment Program (UNEP). The region still has equipment reliant on CFCs, despite commitments to reduce consumption and production these gases.

Under the Montreal Protocol, developing countries agreed to reduce CFC consumption 50 percent by January 2005, and to fully eliminate use by January 2010.

This has led to increased smuggling of these chemicals and hampered adoption of alternatives, UNEP reported in January.

Finally, weather conditions can also exacerbate ozone loss over the polar regions. The Arctic has had fewer and smaller ozone holes than Antarctica but suffered its greatest-ever loss last winter due to extremely cold conditions.

Some experts blame climate change.

As the Earth surface warms, the upper atmosphere is getting colder in the polar regions, creating just the right conditions for chemicals like CFCs and bromine to destroy ozone.

Although more is known about climate change impacts in the Arctic, the same thing could potentially happen in Antarctica, Claus Zehner, of the European Space Agency in Italy, told Tierramérica.

Ultimately, local weather and the degree to which the Montreal Protocol is respected worldwide will determine if there will be ozone holes in the second half of the 21st century, Zehner said.

What’s certain is that this southern hemisphere spring, residents of southern Chile and Argentina, and possibly New Zealand and Australia, will need to protect themselves more than ever from exposure to the Sun’s harmful rays.

(* Stephen Leahy is an IPS correspondent. Originally published Sep. 10 by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme and the United Nations Environment Programme.)