Wednesday, Feb. 24 at 1 p.m. EST.

John Schwartz and fellow Post reporter Curt Suplee discussed global warming and the Antarctic ice.

John Schwartz: Hi, everybody, and welcome to another installment of the online science show. Our guest today is Curt Suplee, a science writer at the Post and editor of our Horizon learning section. There's plenty to talk about, since he's recently been to Antarctica (and, a few months before that, to the Arctic circle.) His story on the southerly trip appeared on Monday. let's open it up for questions. (be sure to ask Curt about going to the bathroom when it's thirty below!)

Atlanta, Georgia: I hear conflicting evidence about the potential detachment of the Antarctic continental glaciers. Presently a few of them are supposed to be frozen to bedrock and therefore not very mobile. Warming is supposed to melt their lock to the bedrock, allowing detachment from bedrock. This thin amount of water is very fluid and "slippery" and may lead to a possible surge of the glacier into the ocean, thus very quickly raising sea levels.
What is the current status of research into this possibility??

John Schwartz: As I understand it, the ice layer itself -- even when it's only a couple thousand meters deep-- is a sufficient insulator that air temperature doesn't affect the bottom of the ice sheets. You're certainly right about the prevailing theory of glacier slippage: That is, they presumably slide along on a sort of slush/mud layer over the rough bedrock. But I haven't heard of anybody who thinks this lubricating layer is susceptible to influence from air temperature. Or even water temperature.

Clifton, VA:

Besides a rise in sea level and ultimately a loss of dry land surface, what are the true threats of glacier melting?

Curt Suplee: That's a book-length question. The biggest changes would be two-fold: What melting would do to global ocean circulation; and what it would do to incoming sunlight.

Ocean water circulates because of differences in the density in different places. Hugely salty, very cold water drops off the edges of antarctic, forming what is called the Antarctic Deep Water. If melting occurred, it would make that water far less salty and presumably warmer, thus messing up the entire circulation system. Potentially.

Second, the Antarctic ice mass reflects an enormous amount of incoming sunlight, especially during the Antarctic (austral) winter when the amount of sea ice around the continental fringe grows five-fold. If that were substantially reduced, much more energy would be absorbed and would warm the continent. With what result? Nobody knows.

Alexandria, VA: Are Antarctica and the Artic's glaciers really melting at a consistent rate? And is the rate increasing each year?

washingtonpost.com: Curt, you've said before that the science of measuring such things is still being worked out, with differences between surface measurement and air measurement... would this be a good time to go into that issue?

Curt Suplee: Nobody knows if the ice is melting at a consistent rate, or even if there is net melting over time. Certainly the ice shelves around the Antarctic Peninsula and the sea ice pack around the north pole are getting beat up pretty good, ostensibly by warming or air, water or both.

But the big ice sheets are another matter. They've been around for literally millions of years, and scientists aren't sure what their normal fluctuation rate is. As a result, it's hard to know whether what's going on now is unusual or ordinary.

That's why there's so much interest in the ice "cores" drilled out of the deep glaciers in Greenland and Antarctica. They contain the climate record for hundreds of thousands of years in the past.

Silver Spring, MD: There doesn't seem to be any clear evidence that global warming is a direct result of human activity, or is a direct threat to human health and the environment. Is there any information you can provide that shows a direct link between industrial activity, global warming, and the state of the environment?

Curt Suplee: Even the experts have trouble with this. You can be reasonably sure that the increase in atmospheric CO2 since the industrial revolution is, at least in part, the result of human activity. But the atmosphere is a big place, and we're talking about a huge amount of carbon. Almost everything people talk about when they say "global warming" means what computer models called GCMs or general circulation models predict.

As for the measured data, they take two -- so far somewhat contradictory -- forms. Surface temperature records seem to show about 1 degree F of warming in the past century. However, the balloon and satellite data, which measure temperature ;in the lower atmosphere where global warming is also supposed to be felt, show no long-term trend. (They do, of course, show a monster spike for 1998's El Nino weather.)

Green Bay Wisconsin: How many of the scientist exploring Global warming, make their living doing it. How long have they been at it and at what cost to the american people.

John Schwartz: I'm not sure that such a question can even be answered, or whether the cost of scientific research lends itself to the kind of cost-benefit analysis you seem to be suggesting. Mathematicians who have puzzled over arcane problems for centuries didn't expect to be giving birth to the world of computing and computer programming, but it happened. I don't know if Curt wants to add anything to this answer, but it's worth thinking about.

Curt Suplee: It depends on what you consider a "large" cost. Some people think that several dozen million dollars for a single military plane is an outrage.

Let's put it this way: Around the United States, there are only a few dozen people who work anything like full time on global warming issues. Many have university positions. Many are paid by the federal government, but do other kinds of work as well.

To cite only one example, the National Center for Atmospheric REsearch in Colo. does a lot of global-warming analysis. But they also do a huge amount of research to assist forecasting and coping with weather phenomena such as El Nino.

What fraction is specifically spent on global warming. I dunno. But it's not much by any measure of federal outlays.

Washington, D.C.: How do we know that satellite observations reflect something other than a normal environmental pattern in the Antarctic?

Curt Suplee: We don't. Climate is a very uncertain thing. Satellite observations only date from the mid-1970s. Most pros will tell you that a couple decades' worth of data are not enough to demonstrate a trend one way or the other.

Washington, D.C.: I've read that much of what is attributed to global warming, including the recent mild winters in Washington, is more a product of urban hot spots than global change. Do you agree with this? Are the temperature readings for say, Hagerstown, Md. substantially different than Baltimore and Washington?

Curt Suplee: A decade ago, it dawns on several climate researchers that the surface temperature record might be skewed because so many of the monitoring locations were in major cities that are subject to what is called the "heat island" effect. That is, they have so much asphalt and concrete that they absorb and hold heat much more readily than surrounding less developed areas.

Since then, however, most climate scientists have adopted data that have been adjusted for this effect, which you can see every night on the TV news forecast. If they're calling for temperatures from 15 to 25 degrees, the 15 is for the grassy suburbs and ex-urbs. The 25 is for the warmer cities.

Lincoln, NE: A few months ago I heard about an ice flow, or an iceberg, about the size of Connecticut, that was about to fall into the ocean (in Antarctica).

Did this really ever happen? And what would the consequence of such a thing be?

Curt Suplee: Those reports come from the ice "shelves" around the Antarctic Peninsula. Ice is always breaking off there, whether because of global warming (a possibility) or normal attrition (equally plausible).

HOWEVER. Those ice lumps are NOT the same as the glaciers. Ice shelves are ice masses that are floating on water but anchored to a land-based sheet of ice. As a result, when one of those puppies cracks off, it doesn't change sea levels at all because it was already floating.

Green Bay Wisconsin: We only here about global warming in the US when we have a warm winter or summer, we do not here about when it is cooler. When we are experiencing this warmth, are their other parts of the world experiencing unusual colder weather.

Curt Suplee: As a rule, very few people in the climate racket think that "global warming" will consist of uninterrupted gradually higher temperatures across the whole planet.

The atmosphere is a "non-linear" system, as they say, and strange things can happen. So far this century, some areas have warmed and others have cooled. Moreover, the warming has been highly uneven.

Most of it has occurred in high latitudes, at night, and in the winter. Greenhouse skeptics like to point out that such developments are pretty attractive to the people who live where the greatest warming is taking place.

Others will tell you that nobody knows exactly how the titanitc atmosphere/ocean/water vapor system will respond to substantial average global temperature increases -- if, in fact, they happen.

washington dc: are animal populations, such as emperor penguins, used as environmental indicators for the effects of fluctuating temperature and ozone depletion? I remember a case several years ago when small birds and amphibians were dying at the equator due to, what was thought to be, excessive radiation.

John Schwartz: The environmental equivalent of canaries in the mine shaft, right? Curt, the Antarctic fauna is pretty sparse, from your description--what does the research on the animals tell us so far?

Curt Suplee: Lots of folks are looking at penguins and birds as "proxy" indicators of possible climate change. But it's tough. For one thing, almost nothing lives in Antarctica. (And who can blame 'em!) For another, when one species does poorly, another can benefit. That seems to be true of different penguin species. Those that are highly dependent on ice cover (under which their lunch swims) do poorly when the ice declines, as it apparently is now doing around the peninsula.

But down around the Ross Sea, there appears to be more ice than usual these days, and penguin populations there are burgeoning.

Bottom line: It looks like it's going to take many more years of research before this question can be answered conclusively.

Washington DC: Due to global warming and melting ice caps it is inevitable that rising sea levels within the next 100
years will displace millions of people living along our nation's coast. What is our government doing to prepare for eventual ecological disaster?

John Schwartz: Inevitable? Millions? Curt, would you like to bring these estimates into a range more generally recognized by scientists who study global warming?

Curt Suplee: Few of the folks I talk to would agree with you that substantial sea-level rise is anything like inevitable. Pretty much everybody agrees that the ocean is rising, at an annual rate of about 1 mm (approx the thickness of a dime).

At that rate, if it remains constant, the threat to even the most coastal of the world's populations is not huge.

Darien, IL: I read a few years ago about sheep in the southernmost tip of South America going blind because of the thinning of the ozone layer over the South Pole. Is this true? What can we, as consumers do to decrease ozone depletion in a way that will have the most impact on our planet for the better. I wanted to buy a solar powered car but they are simply not available in my area and I've yet to see any kind of solar or electrical recharging station for these vehicles. Are the car makers behind this glacial pace of innovation? I've read that in Japan, they already have a hybrid model that costs about $16000 but the U.S. car makers are angry at Toyota for charging too low a price for these vehicles. Apparently, they would rather have environmentally friendly cars priced out of the market?

Is there collusion between energy suppliers and car makers? What's going on?
Marina

Curt Suplee: As far as I know (a highly limited range), nobody has ever quite confirmed those vision-challenged sheep. Moreover, most experts now agree that although ozone depletion is pretty bad, it's on its way to turning around -- thanks in large measure to the Montreal Protocol that banned certain chlorofluorocarbons.

Meanwhile, however, buying electric cars will have no impact on stratospheric ozone. Internal combustion engines release nitrogen oxides that help create LOW-LEVEL ozone of the sort you can breathe any down out by the interstate.

Washington, DC: I thought there was more ice at the North Pole. Guess I was wrong. What's the difference between the Arctic Circle and Antarctica?

John Schwartz: You mean besides the fact that there's no land under the North Pole and Antarctica is a vast continent? Curt, as the only guy I know who's been to both places (talk about going around the world the hard way!) might want to elaborate on this.

Curt Suplee: Nope. There's a lot more ice in Antarctica. As the kids say, it's WAY cool. For one thing, there's no land under the north pole. There's a lot of floating sea ice there, but nothing for it to get anchored on.

Antarctica, by contrast, is a continent of 5.5 million square miles -- about 50 percent larger than the US -- and contains 90 percent of the world's fresh water bound up in ice.

Seattle, Washington: What is the latest scientific thinking on the relation, if any, between global warming and the damage to coral reefs that's been observed in many places?

Curt Suplee: Apparently warmer sea waters can lead to deterioration and "bleaching" of coral reefs. This is a documented phenomenon and very bad news if you happen to live in one.

Clifton, VA:

Politicians have long been using the "threat of global warming" and meeting the goals of the Clean Air Act as one of their campaign ploys to gain votes. But while human-created pollution from factories and auto-exhaust could easily be viewed as a contributor to the "greenhouse effect," isn't it true that volcanic dust and ash is the most concentrated, or at least the most abundant contributor to global warming?

Curt Suplee: Well, actually, no. Volcanic dust and ash have the effect of cooling the planet's surface. For one thing, they block sunlight on its way down. But in some circumstances they can also make the air and clouds a bit shinier, so that they reflect more incoming sunlight out into space.

That's why the eruption of Mt. Pinatubo was followed by a months-long cooling trend across the Earth;'s mid-latitudes.

Bethesda, MD: What is the correlation (if any) between global warming and ozone depletion?

Curt Suplee: As recently as a few years ago, even a lot of experts would have said that there wasn't any.

Now, however, the thinking is that ozone depletion (which requires not only CFC-like compounds, but nifty little ice-crystal platforms on which they can work)IS affected by stratospheric temperature.

And since stratospheric (upper atmosphere) temperature is influenced by tropospheric (lower atmosphere) temperature, it now appears that there MIGHT WELL BE a relation between the two effects.

BUt how big it might be is very uncertain.

Potomac, MD: John:

Do you think terms like "climate change" and "global warming" been used to prematurely cut-off debate about the effect, if any, of manmade emissions of greenhouse on global climate -- whatever that it is?

John Schwartz: An excellent question: does the loud argument over scientific issues make it harder to discuss those issues?

Curt Suplee: Whatever the effect of using those terms has been, it sure HASN'T been to cut off debate.

If anything, the debate is sharper and more polarized now than it was in the late 1980s when a substantial fraction of national publications were carrying "doomsday" warnings about impending warming.

Also, those terms seem pretty color-neutral to me.

College Park, MD: Getting back to what the average person can do...What can we do (assuming the worst and global climate is greatly effected by human activity)?

Curt Suplee: I don't want to seem like a greenhouse wimp, but policy stuff is way outside my mandate. We try not to express opinions on stuff like this even if we have 'em.

John Schwartz: Well, everybody, that's all the time we have for today. Thanks for coming along for the read, and thanks to Curt Suplee, global encircler, for showing up and typing his fingers to the nub. We have this discussion about science, technology and more once a month, and I hope you'll tune in next time to see who our next victim--er, guest--is. See you next time!