Ozone-Friendly Chemicals Lead to Warming

AP ^ | 8/20/6 | JOHN HEILPRIN

[SmithL]

Cool your home, warm the planet. When more than two dozen countries undertook in 1989 to fix the ozone hole over Antarctica, they began replacing chloroflourocarbons in refrigerators, air conditioners and hair spray.

But they had little idea that using other gases that contain chlorine or fluorine instead also would contribute greatly to global warming.

CFCs destroy ozone, the atmospheric layer that helps protect against the sun's most harmful rays, and trap the earth's heat, contributing to a rise in average surface temperatures.

In theory, the ban should have helped both problems. But the countries that first signed the Montreal Protocol 17 years ago failed to recognize that CFC users would seek out the cheapest available alternative.

The chemicals that replaced CFCs are better for the ozone layer, but do little to help global warming. These chemicals, too, act as a reflective layer in the atmosphere that traps heat like a greenhouse.

That effect is at odds with the intent of a second treaty, drawn up in Kyoto, Japan, in 1997 by the same countries behind the Montreal pact. In fact, the volume of greenhouse gases created as a result of the Montreal agreement's phaseout of CFCs is two times to three times the amount of global-warming carbon dioxide the Kyoto agreement is supposed to eliminate.

This unintended consequence now haunts the nations that signed both U.N. treaties.

[marblehead17]

ping

[Fire_on_High]

Oink!

[TX Bluebonnet]

*snicker*

I love your graphic!

[sully777]

My new A/C units for home and car SUCK SUCK SUCK. IRC the gases used to cool are more poisonous than freon for the environment.

[ConservativeMind]

And they wonder why it's warming?

[cogitator]

It is my unstudied opinion that no reputable scientists has ever stated how CFCs that i use in my car air conditioner in upper New York State makes in to the stratosphere over Antarctica to interact with the O3 when the sun shines on it. ... In fact, I am interested in the general problem of atmospheric interchange between the northern and southern hemisphere if someone can point me to some references.

It's been studied. ;-)

Chapter 6: Stratospheric Dynamics and the Transport of Ozone and Other Trace Gases

The part you want in particular is Section 3, the Brewer-Dobson Circulation. It seems at first glance to be somewhat counter-intuitive -- and I do not claim to understand it well. But... from what I can gather on first reading, the CFCs are transported to the tropics by the standard Hadley cell circulation. They are transported to the stratosphere from the troposphere in the tropics. Then it gets interesting -- clearly the Brewer-Dobson circulation transports the CFCs poleward. But there isn't much about mixing over the ITCZ which would enable CFCs from the Northern Hemisphere to get into the Southern Hemisphere. Of course, some CFCs are generated in the SH, but not as much as in the NH.

This reference:

Estimating CFC Air Curves

says that interhemispheric mixing times are 1.1 - 1.4 years. That's much faster than I would have expected. (It also says that 95% of the CFCs are released in the NH.)

Ooooh... this paper indicates that interhemispheric exchange can be explained (well, 78% of it, at least) by seasonal oscillation of the Hadley cell circulation. That may be the key you're looking for.

Interhemispheric Exchange by Seasonal Modulation of the Hadley Circulation (PDF)

I hope that will be helpful to you.

[palmer]

Wouldn't they also act as a refelective layer for incoming sunlight, thereby causing Global Cooling?

Most gasses reflect (or absorb and then reradiate) longwave radiation, aka heat, while letting shortwave radiation (sunlight) through. The spectra vary but I imagine these are particularly opaque to LW radiation.

[Outland]

"These chemicals, too, act as a reflective layer in the atmosphere that traps heat like a greenhouse."

A greenhouse doesn't work like this at all.  What idiots.

The glass in a greenhouse let's sunlight enter, but traps heated air by preventing convection of the air to the outside. There is a minimal effect of reflection from the inside surface of the glass, but not enough to trap significant heat at night (which is why many greenhouses in cooler areas are heated).. Any coating on the glass that would reflect infrared back to the inside of the greenhouse would also block much of it from entering.

[Outland]

I've often wondered how CFCs could migrate into the upper atmosphere myself, considering that these molecules are extremely heavy.

Having worked with various CFC compounds in the past, the only hazard warnings that were common was the danger of suffocation in low areas because the CFC vapors would displace air.

As I understand it, the CFCs interact with O3 after breaking down into chlorine. In this case, it's actually chlorine that does the dirty work. If so, I believe the major source of free chlorine would be from all the chlorinated municipal water systems and not as much from A/C and refridgerarion systems.

By the way... I'm still using my old Frigidaire air conditioner with genuine Freon in it. I won't part with it.

[cogitator]

And due to the problems and logistics of replacing freon with other alternatives, what has been the cost we've paid to make this ineffective switch?

Why do you call it ineffective? Stratospheric ozone levels are recovering (slower than expected, but they are recovering) because of the CFC phase-out. The global warming aspect of HFCs and HCFCs is a down-side, but energy conservation and new energy technology can compensate. The Montreal Protocol is an example of the international community doing the right thing when faced with a potential enviromental crisis for which the causes and effects both were relatively simple to characterize. I state that last part because global warming is not the same, there are multiple causes and a wide range of potential effects.

[cogitator]

I've often wondered how CFCs could migrate into the upper atmosphere myself, considering that these molecules are extremely heavy.

They're long-lived and relatively inert. The excellent Web site from which I culled some links for Citizen Tom Paine discusses this. It takes a while for the CFCs to get to the stratosphere, but they do get there.

As I understand it, the CFCs interact with O3 after breaking down into chlorine. In this case, it's actually chlorine that does the dirty work. If so, I believe the major source of free chlorine would be from all the chlorinated municipal water systems and not as much from A/C and refridgerarion systems.

Free chlorine in the troposphere won't get to the stratosphere, because it's too reactive. That's why HCl from normal volcanic activity gets washed out of the atmosphere by rain. CFCs get to the stratosphere and are then broken down by high-powered radiation to release chlorine. (Note that it really helps to have polar ice clouds to furnish surfaces for catalytic breakdown of ozone.)

[cogitator]

The ineffective part was based on this article.

That's why I responded. HCFCs and HFCs are good for the ozone layer, but they are just as "bad" as CFCs with regard to global warming. But for the purpose of protecting the ozone layer, HCFCs and HFCs aren't ineffective.

And what do we get for a cleaner atmosphere? Scientists are complaining that cleaner air is letting more sunlight-caused global warming through!

Well, we get less acid rain, less soot, less of this:

(Photo taken during London's 1952 "killer fog").

CO2 and global warming can be dealt with -- provided enough people are motivated to deal with it. And the current energy crunch provides a good source for motivation, I think.