. Earth Science News .

Ozone Depletion a Bigger Deal Down Under
by Christina Coleman for Goddard Space Flight Center
Greenbelt MD (SPX) Oct 24, 2011

File image

The Earth's thinning ozone layer is synonymous with a singing and dancing seagull named Sid - at least it is in New Zealand and Australia.

"This time of year there is a huge push to 'Slip, Slop, Slap,'" says Hamish Talbot, a native New Zealander. These publicly funded commercials implore people to "slip" on a t-shirt, "slop" on some sunscreen and "slap" on a hat.

All this protection is necessary because New Zealand's location in the Southern Hemisphere puts it very close to the "ozone hole" that forms over the South Pole at this time every year. The ozone is so thin in this part of the world that the weather report on the nightly news includes five-minute sunburn alerts.

Ozone is Earth's natural sunscreen. The ozone layer in the upper atmosphere, or stratosphere, absorbs harmful ultraviolet rays from the sun. In the 1980s, scientists discovered that manmade chemicals destroy ozone to the point where an actual ozone hole occurs.

The good news is that this hole isn't getting any larger.

"In fact, we have definitive evidence to show that these manmade chemicals are decreasing," says Paul Newman, NASA Goddard Space Flight Center's chief atmospheric scientist.

These chemicals, chlorofluorocarbons (CFCs), peaked in the year 2000 and began coming down due to actions taken to save the protective ozone layer beginning in the1980s. That's when nearly 200 nations agreed to the Montreal Protocol, which strongly regulates ozone-depleting chemicals.

Scientists believe that about 80 percent of the chlorine molecules in the stratosphere are due to human-produced chemicals. Halogens such as chlorine and bromine, which are mainly responsible for chemical ozone depletion, come from chlorine-containing CFCs, which were commonly used as aerosols and in refrigerators, and bromine-containing halons, which were used in fire suppression, among other uses.

Originally thought to be harmless, scientists discovered that these chemicals travel into Earth's stratosphere. Once there, ultraviolet radiation splits the CFCs or halons apart, and the chlorine and bromine containing molecules can then react with ozone, ultimately tearing away at the ozone layer.

Even though CFCs are now regulated, Newman cautions that they have a long lifetime.

"In 2100, CFCs will still be 20 percent more abundant in the atmosphere than they were in 1950. So while it's not getting any worse, it won't get better fast."

A complication to this chemistry is cold temperatures.

"Surface temperature doesn't affect ozone, but it is extraordinarily cold about 70,000 feet above Antarctica," Newman says.

At that altitude, clouds form in the polar regions that enable a chemistry to occur that doesn't happen anywhere else. "These clouds are made up of water, nitric acid and sulfuric acid," Newman says.

These clouds kick start the process by releasing chlorine from a chemically inactive form into a form that can catalytically destroy ozone. With a little bit of sunlight to energize the reactions, a chlorine atom can destroy thousands of ozone molecules.

"So you need CFCs for the chlorine, really cold temperatures for the clouds, and a little bit of sun. That's the recipe for the ozone hole," Newman says.

While it is very hard to predict year-to-year stratospheric temperatures, scientists have been able to measure the success of ozone protection efforts for more than 40 years using NASA satellites. Data records began with the NASA Backscatter UltraViolet (BUV) Instrument on Nimbus-4 in 1970.

By 1979, scientists were able to measure the size of the ozone hole using NASA's Total Ozone Mapping Spectrometer (TOMS). The record continued with the Ozone Monitoring Instrument (OMI), supplied by the Netherlands and Finland on the NASA Earth Observing System satellite Aura.

"At first scientists made predictions that chlorine was destroying the ozone, and we indeed found that it was happening," Newman says. "Now the challenge is to confirm that our predictions of ozone recovery are playing out as we said they would."

Researchers will continue to collect ozone data with the launch of the NPOESS Preparatory Project (NPP), scheduled for Oct. 28. Aboard NPP is the Ozone Mapping and Profiler Suite (OMPS), a new design consisting of two ozone-measuring instruments.

The 'limb profiler' views the edge of the atmosphere from an angle to help scientists observe ozone at various levels above the Earth's surface, including the protective ozone layer in the stratosphere. The other instrument is "nadir-viewing," meaning it looks down from the satellite, measuring the total amount of ozone between the ground and the atmosphere.

NASA satellite data and models predict that the ozone hole will not return to pre-1980 levels for decades. In the meantime, Newman says OMPS will continue the data record into the future - and additional ozone-monitoring instruments are already planned for after NPP.

"We need to really care about the ozone because it is our natural sunscreen. UV radiation can lead to skin cancer, cause cataracts, suppreses the immune system, impact crops, and contribute to degradation of materials," says Newman.

While OMPS and other instruments will continue to monitor the health of our ozone layer, the fact that it will take a long time for our atmosphere to recover from the damage caused by CFCs, means that Sid the Seagull will keep on singing "Slip, Slop, Slap" - warning people to spend less time outside and more time under a floppy hat.

Related Links
Ozone Watch at NASA
All about the Ozone Layer

Get Our Free Newsletters Via Email
Buy Advertising Editorial Enquiries


. Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Scientists worried as Arctic has record ozone loss
Paris (AFP) Oct 2, 2011
An ozone hole five times the size of California opened over the Arctic this spring, matching ozone loss over Antarctica for the first time on record, scientists said on Sunday. Formed by a deep chill over the North Pole, the unprecedented hole at one point shifted over eastern Europe, Russia and Mongolia, exposing populations to higher, but unsustained, levels of ultra-violet light. Ozon ... read more

Rice regrets shoe shopping amid Katrina disaster: book

Radiation hotspot near Tokyo linked to Fukushima: officials

Use Japan nuke disaster to reform mental health system: WHO

Wall collapses at Pompei after flash storms

Space Waste Transporter: Going Where No Garbage Man has Gone Before

ROSAT re-entered atmosphere over Bay of Bengal

German satellite re-enters Earth's atmosphere

Proposal would 'recycle' satellite parts

China the culprit of potential water wars?

Run-off, emissions deliver double whammy to coastal marine creatures

Jet packs rule, say deep-sea astronauts

Brazil pulls out of OAS meet over Amazon dam dispute

China's glaciers in meltdown mode: study

Extreme Melting on Greenland Ice Sheet

Glaciers in China shrinking with warming

Polar bear habitats expected to shrink dramatically:

Putting light-harvesters on the spot

Breakthrough in the production of flood-tolerant crops

How plants sense low oxygen levels to survive flooding

Stem Rust-resistant Wheat Landraces Identified

Fiery volcano offers geologic glimpse into land that time forgot

Bangkok set for unstoppable floodwaters

Hurricane Rina strengthens, takes aim at Cancun

Turkey's ethnic tension boils over in quake-hit city

France denies Somali bombardment, admits helping Kenya

US troops to advise front-line units on Uganda rebels

Sudden drop in Somali arrivals in Kenya: UNHCR

Kenya, Uganda snared in Battle for Africa

Tracing the first North American hunters

Culture in humans and apes has the same evolutionary roots

Crowded Earth: how many is too many

'Generation Squeezed': today's family staggering under the pressure


The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement