NASA Announces Record Ozone Hole

Drewsk writes "NASA has announced that the ozone hole over the Antarctic has broken all records. From the story: 'From September 21 to 30, the average area of the ozone hole was the largest ever observed, at 10.6 million square miles,' said Paul Newman, atmospheric scientist at NASA's Goddard Space Flight Center, Greenbelt, Md. If the stratospheric weather conditions had been normal, the ozone hole would be expected to reach a size of about 8.9 to 9.3 million square miles, about the surface area of North America.""

Comments

Re:Great

[Apparissus]

RTFA. It kindly mentions that

A) Chlorine, Bromine, and their Ozone cappin' friends stay in the atmosphere for decades. Even with a significant drop in emissions (its precipitousness is reminiscent of the bunny slope) it will be a very long time before significant positive effects accrue. As the article points out, we can expect about 0.1% to 0.2% per year in the near term.

B) This record breaking event is the culmination of several phenomena, including large-scale, seasonal factors that completely overshadow the tiny bit of healing the layer has done in the last few years. "This slow decrease is masked by large year-to-year variations caused by Antarctic stratosphere weather fluctuations."

One thing the article does NOT mention is any cry of "Wolf!". There isn't any environmentalist finger-wagging, just some scientists saying "holy shnikes, take a look at the SIZE of that thing!!"

Where the ozone comes from

[Beryllium Sphere(tm)]

The ozone we're concerned about here is formed by solar ultraviolet in the stratosphere. Almost all thunderstorm activity is in the troposphere. The ozone that thunderstorms and photochemical smog produce only lasts a few weeks.

Now, if you want to get confused, CFCs are both catalysts of ozone breakdown and greenhouse gases. To make you even more confused, upper tropospheric ozone is a greenhouse gas, not as important as CO2 but worth taking into account.

Re:Sometimes...

[kfg]

Sure! Your intuition is far more powerful than 100 years of scien-ma-tific observation.

Although the presence of ozone in the atmosphere has been known for a bit over 100 years, knowledge of the presence of a permanent ozone layer is rather more recent. Man did not reach the south pole until 1912 and did not fly over it until 1929. The first permanent observation station at the south pole was not established until 1957. Meanwhile the ability measure the thickness of the ozone layer, from either ground or satellite is concurrent with the discovery of the ozone hole. Mid 70s through mid 80s. Although ballons have been flying into the stratosphere for a couple ticks over 100 years, we only got a good idea of its structure in the mid 80s when we sent up an instrumented U2. OP is right to the extent that we really know squat all about the history of the ozone layer.

Go back to eighth grade science class, then come back and post on slashdot.

I had just finished my undergraduate studies in physics when we first started acurately measuring the thickness of the ozone layer indirectly; and thus being able actually map it. Perhaps you have the advantage on me of only recently being out of the eighth grade.

KFG

It never went away

[astro-g]

certainly not for those of us who have to live under it.

I live in New Zealand, the current position and shape of the ozone hole is a regular feature of TV weather reports.

Re:Was Wondering...

[Anonymous Coward]

Confusingly, an interviewed scientist was also commenting that people shouldn't panic, because it was on a downward trend and was still expected to heal itself over the next so many decades. I'm not quite sure exactly what was meant, because under most circumstances I wouldn't intuitively consider a "largest ever recorded value" to play any part in a measured downward trend.

There are two possibilities that don't defy logic:

• The depletion of the ozone is increasing but the rate of increase is decreasing. Logically there will eventually be a point at which the depletion rate reaches a zero value and then goes negative resulting in a regeneration of the ozone layer.
  
• The record size hole was a statistical anomaly in data that showed that over a period of many years that the ozone layer is rebuilding. As long as the value of the statistical anomaly doesn't fall further than say 2.5 times the standard deviation from the curve fit, then it could have been just due to random error. And if it wasn't then the error would be systematic error but could probably be explained by changing climate conditions (such as Antarctica being colder than normal).

Re:Your questions answered

[Anonymous Coward]

no-one has ever explained how CFC molecules which are much heavier than air, can rise up in the stratosphere, travel all of the way to Antarctica before being broken down into chlorine and fluorine and reacting the O3

Maybe not, but they're there. All the same tools that tell us whats in other planets' atmospheres works equally well on our own. Further more, as surprising as it may be, if you lay down on the ground, you're not likely to asphyxiate unless someone dumps a sufficient amount of a heavy gas right next to you, since the atmosphere mixes up rather easily. As for how they move, I'm going to suggest things like the Jet Stream for moving them around the planet, and equatorial heating to carry CFCs into the upper atmosphere and down towards the pole.

Chlorine in the ice

Interesting theory. Where did the chlorine come from? A molecule of Cl2 (total atomic mass 71) is more massive than N2 (28), O2 (32), and CO2 (44), or does "too heavy" only count when it's you saying it? Could it possibly be that the Cl in your ice is the same Cl in CFCs?

thus turning your refrigerator into a potential BOMB.

Aside from someone else already pointing out that it's not benzene, I guess you're too young to remember the days of early ammonia refrigerators, now those were the BOMB!

Re:Damned if you do.....

[Orp]

Same goes to the douche who thinks "CFCs are too heavy to get into the Stratosphere". I'm not going to bother to explain that one to you.

Actually, I'd really like to hear an explanation. I'm not going to claim to know anything about CFC's, but if these gases really are heavier than air and don't readily mix with air, how exactly does a bucket of them in my back yard elevate itself to the upper atmosphere?

Think of it this way: What is "air" in the first place? To a good approximation within the troposphere, it's a mixture of molecular oxygen (molecular weight = 32 grams/mol, 21%), molecular nitrogen (MW = 28 g/mol, 78%) and argon (MW = 40 g/mol, .9%). If the heaviest gases simply sunk to the bottom, we would be suffocated by argon near the ground and all of the nitrogen would be on the top of the atmosphere, with the oxygen in the middle.

The troposphere (tropos in Latin means "turning" or "mixing") is well-mixed and the relative ratio of the three aforementioned permanent gaes to one another is constant. If you introduce a heavier gas (higher MW) it will still get mixed into the lighter gases over time due to the winds. Brownian motion will also cause heavier gases to diffuse in a calm environment.

CFCs will spread laterally across the globe by the horizontal winds. Whenever there is a strong thunderstorm, updrafts will slam air, which originates near the ground, into the tropopause, the boundary between the troposphere and the stratosphere. Very strong updrafts can intrude into the bottom of the stratosphere where the tropospheric air mixes into the stratosphere. Once something gets into the stratosphere (if it's got a very small terminal velocity - think about strong volcanoes spewing ash) it tends to stick around because the stability of the stratosphere is so high (due to the temperature inversion I mentioned before).

Back to "heavier gases" for a moment. It is true that if you "pour" a heavy gas onto the ground it will spread out before mixing. There have been cases where CO2 (MW = 34) has seeped out of the ground and spread laterally, suffocating people (google Lake Nyos). But given a few hours of typical winds, the heavier gas will be diluted and over time mixes into the rest of the atmosphere, contributing slightly towards the atmosphere's own average molecular weight.