Chilling Effects of Climate Change in the Antarctic

[G_j]

http://www.commondreams.org/headlines05/1013-03.htm

Published on Thursday, October 13, 2005 by Inter Press Service

Chilling Effects of Climate Change in the Antarctic
by Gustavo González

SANTIAGO - Climate change, which the scientific community links to the increased intensity of tropical storms and other extreme weather phenomena, is also making itself felt in Antarctica, where the "hole" in the ozone layer continues to grow and the increasing break-up of the ice shelves could have played a role in the recent deaths of Argentine and Chilean scientists and members of the military.


"The hole in the ozone layer expanded this year, and the quantity of ozone destroyed within that area increased as well," Bedrich Magas, a researcher with the University of Magallanes, told IPS from the city of Punta Arenas. Magas carries out daily measurements of ultraviolet radiation in the port city of 120,000, located at the southern tip of Chile.

According to the Argentine Antarctic Institute, in September - the start of the southern hemisphere spring - the hole in the ozone layer reached 28 million square kilometres, representing an eight percent increase from 2004. In addition, the ozone value dropped from 95 to 87 Dobson Units (a measure of the "thickness" of the ozone layer, with 220 units considered the acceptable lower limit).

In satellite images, the hole appears as a fluctuating oval-shaped area that in the most critical period - which peaks in September and October - stretches from Antarctica to the southern part of South America, affecting cities in southern Argentina and Chile like Punta Arenas, 1,000 km north of the Antarctic's King George Island and 2,300 km south of Santiago.


..more..

[On the Road]

1. What Does the Ozone Hole Have to Do with Global Warming?

I thought that was a matter of greenhouse gases. Just curious. And I thought the ozone hole had stabilized and would eventually retreat due to the ban on CFCs.

[mike_c]

2. here you go....

http://www.gsfc.nasa.gov/topstory/20020422greengas.html

CLIMATE CHANGE MAY BECOME MAJOR PLAYER IN OZONE LOSS

While industrial products like chlorofluorocarbons are largely responsible for current ozone depletion, a NASA study finds that by the 2030s climate change may surpass chlorofluorocarbons (CFCs) as the main driver of overall ozone loss.

Drew Shindell, an atmospheric scientist from NASA's Goddard Institute for Space Studies (GISS) and Columbia University, N.Y., finds that greenhouse gases like methane and carbon dioxide are changing the climate in many ways. Some of those effects include water vapor increases and temperature changes in the upper atmosphere, which may delay future ozone recovery over heavily populated areas.

Scientists have expected the ozone layer to recover as a result of international agreements to ban CFCs that destroy ozone. CFCs, once used in cooling systems and aerosols, can last for decades in the upper atmosphere, where they break down, react with ozone, and destroy it. They remain the major cause of present-day ozone depletion.

[On the Road]

6. Thank You, Mike C, That's a New One for Me

not good news.

[hatrack]

4. More heat trapped near the surface means less re-radiating out to space

The upper atmosphere grows colder as a result.

The colder, the better, at least in terms of the efficient operations of CFCs released into the stratosphere, and over the Poles, w/o light for months at a time, it gets very cold indeed.

So while it's not as direct a connection as "more GHG = more heat trapped", it's only one step removed.

[On the Road]

7. So It's Not the Greenhouse Gases Themselves

that destroy the ozone (like CFCs do), but the lower temperatures they create in the stratosphere? Never understood how the effects vary by altitude.

[hatrack]

8. Correct - not directly

I posted some time back that the mesosphere - the next layer above the stratosphere - had been cooling at something like 10X the previously recorded rate - though admittedly there isn't as much mesosphere data as we'd like.

[jpak]

10. It's the reactive chlorine (ClO) that destroys stratospheric ozone

It's derived from the photo-oxidation of CFC's and is present in an unreactive form (ClONO2) at temperatures greater than -80 degrees C.

At temperatures below -80 degrees C, the formation of polar stratospheric clouds initiates denitrification reactions that liberates ClO, which subsequently destroys ozone at sunrise in the Antarctic spring.

There are two mechanisms that are currently cooling the stratosphere and creating conditions more favorable to the formation of polar stratospheric clouds - the accumulation of greenhouse gases in the troposphere (which reduces upwelling infrared radiation that warms the stratosphere) and the destruction of stratospheric ozone by man-made halocarbons (ozone is a greenhouse gas that warms the stratosphere - this a positive feedback).

Other man-made effects that potentially influence stratospheric ozone depletion are increased transport of methane to the stratosphere (it's oxidized to water vapor and CO2 - increased water vapor concentrations favor the formation of polar stratospheric clouds) and enhanced transport of anthropogenic nitrous oxide to the stratosphere (it's transformed to NOx that destroys ozone).

In Antarctica, the formation of the Ozone Hole greatly enhances the flux of UVB (the portion of ultraviolet radiation spectrum that damages DNA) to the Earth's surface. UVB measurements at Palmer Station during periods of depleted total column ozone can rival UVB fluxes at the Equator - and it does a real number on marine micro-organisms down there...

[Lisa]

16. ice crystals apparently help accelerate the process ...

I remember reading something to that effect -- that they help concentrate the chlorine and other ozone-depleting chemicals.

And a couple of other things too, maybe? The cold temperatures inhibit processes that would remove those ODCs from the atmosphere, and also suppress the formation of nitrogen compounds which would otherwise interfere with the ozone destruction?

[Grey]

3. Dobson Units (a measure of the "thickness" ......

:rofl: O8) Sorry, that just struck me as funny.
Very good article. Thanks, I'll be quiet now.

[Cessna Invesco Palin]

5. Beat me to the punch. n/t

[Lisa]

14. oddly appropriate, isn't it!

100 Dobson Units (what they use to measure ozone) would translate to 1 mm of pure ozone, at standard temperature and pressure (1 atm, 0 degrees C).

So basically, the stratospheric ozone layer is 3-5 mm thick at the BEST of times (though it's actually spread several miles deep in the stratosphere). And seeing it dropping below 1 mm is a sign that things are definitely out of whack.

[existentialist]

9. Question: Would it also be true

that simply more ultraviolet radiation making it through the upper atmosphere also simply means more radiation breaking down into heat on or near the surface?

Wouldn't this also contribute to global warming?


Is this true but so small relative to the other factors that it is relatively insignificant?

[existentialist]

11. World Temperatures Keep Rising With a Hot 2005

http://www.washingtonpost.com/wp-dyn/content/article/2005/10/12/AR2005101202498_pf.html

World Temperatures Keep Rising With a Hot 2005
By Juliet Eilperin
Washington Post Staff Writer

Thursday, October 13, 2005; A01

New international climate data show that 2005 is on track to be the hottest year on record, continuing a 25-year trend of rising global temperatures.

Climatologists at NASA's Goddard Institute for Space Studies calculated the record-breaking global average temperature, which now surpasses 1998's record by a tenth of a degree Fahrenheit, from readings taken at 7,200 weather stations scattered around the world.
The new analysis comes as government and independent scientists are reporting other dramatic signs of global warming, such as the record shrinkage of the Arctic sea ice cover and unprecedented high ocean temperatures in the Gulf of Mexico.

Late last month, a team of University of Colorado and NASA scientists announced that the Arctic sea ice cap shrank this summer to 200 million square miles, 500,000 square miles less than its average area between 1979 and 2000. And a scientist at the National Oceanic and Atmospheric Administration determined that sea surface temperatures in the Gulf of Mexico were higher in August than at any time since 1890, which may have contributed to the intense hurricanes that struck the region this year.

[Karenina]

12. "I'm melting! I'm melting!"

cried the Wicked Witch of the East... :silly:

[skipos]

13. Can someone please get this info to dipshits like Pat Robertson? nt

[Lisa]

15. yes, in theory some of that UV would make it to the surface ...

...although some of it could be intercepted by growing amounts of ground-level ozone, or photochemical smog, generated close to the surface by car emissions, etc.

And assuming that it actually got absorbed (rather than bounced back into space by stuff like ice and snow cover, which reflects UV as well as visible wavelengths) -- yeah, that would add to the energy load. Especially since we've already lost a fair amount of that snow and ice cover, thanks to -- you guessed it -- global warming.


I remember discussing this with my climatology prof back in the 1980s. I tried to argue that it WOULD make a big difference (but so far, the climate change literature from the past couple of decades is more in agreement with him). He noted that there is actually not that much overall energy in the UV wavelengths, compared to a) the incoming VISIBLE wavelengths from the sun (where most of the sun's energy is concentrated), and b) the outgoing infrared radiation from the Earth's surface. Both the Earth and the sun give off energy, but of course the Earth's giving off longer weaker wavelengths since it's so much cooler.



See the following diagram. The UV energy would be on the far left-hand side of the "sun" curve ... if you look at the total area (amount of energy), it's actually not as much as the visible and longwave components in the system. So it would add to the problem -- but likely not as much as an albedo (surface reflectivity) change due to urbanization, or deforestation, or the snow-ice positive feedback noted earlier.