Wednesday, January 23, 2008

Science Lesson Part I

I promised the other day that I'd actually write something substantive about science, so here it is. (I can't resist mentioning it though: I did indeed take my record-breaking third shower of the season a few days ago...)

I had a really interesting conversation yesterday with this professor from Dartmouth who just arrived at the Pole as part of a joint Norwegian-US Traverse, and I think it may spawn another Economist article. It has to do with ice sheets, global warming, rising sea levels, and how you go about figuring all this stuff out.

Let me back up a little bit. Everyone knows about global warming. And everyone knows that one of the really bad things that could happen with global warming is a rise in global sea levels. There's this nice google map that shows what parts of the world will get flooded when sea levels rise. It's pretty cool. You can adjust the amount of sea level rise and then check out your own favorite neighborhood-Bangladesh, Manhattan, Florida, etc.- to see if it's still above water or not. Anyway, rising sea levels come from two things. First off, as temperatures increase, water expands. This is just basic science: hotter things take up more room. In a hot air balloon, turning on the flame heats the air in the balloon. The air expands and the balloon becomes buoyant.

The second cause is the big one. When you melt ice that's sitting on land (such as the three mile thick ice sheet I'm sitting on right now), the water flows into the ocean and causes the sea level to rise. Just to be clear, this only happens for ice sitting on land, not ice that's already floating on water. The usual analogy is an icecube in a full glass of water. When it melts, the glass doesn't overflow. This is because the meltwater takes up the space that the ice was already taking up. Because of this, all the stuff you see on the melting of the Artic and the North Pole doesn't contribute to rising sea levels. That ice was already floating in water. The melting of the Artic is alarming for other reasons which I won't get into right now...

This brings me back to Antarctica. Most of the Earth's fresh water is locked up in the icesheets here, so obviously what they're doing is really important for sea levels. We do know that West Antarctica, the part that juts out towards South America, is warming up and melting really quickly. The problem is that the ice in East Antarctica, the huge part closer to where I am, may actually be getting thicker. That's because, in a warmer climate, it's expected to snow more. That snow falls onto the ice and stays there. If more snow falls than ice melts, the sea level actually goes back down.

So here's the real kicker: we don't actually know if Antarctica is losing ice or gaining ice, overall. There are models and calculations and some satellite data, but there's very little on the ground data from East Antarctica. We just don't know. I even think the recent IPCC report concluded that it was too early to say whether Antarctica is losing ice or not (though I have to check on that).

This is all an interesting little tidbit. One that doesn't usually get reported amidst all the scary stuff you see on the news. I'm guessing the media thinks that people are too stupid to digest complicated information. "Well, if Antarctica isn't melting, that means that global warming isn't real and we don't have to do anything about it." I trust you guys more than that.

So how do we figure out what's really happening in East Antarctica? I'll save that for Science Lesson Part II. But for those of you who just can't wait, I'll give you a preview: You get in some tractors and you spend two-and-a-half months driving across the ice...

8 comments:

wbain said...

Phew! I was getting really bored reading about near-death experiences involving snowmobiles, self-indulgent congressional delegations, and the far-flung reach of Old Glory and American Empire even to the South Pole--so its pretty refreshing instead to get a technical discourse on keep me entertained. One note--I suspect that sea level rise will be catastrophic--i.e. a piece of ice will tumble into the ocean and raise sea levels quickly. Whereas, the slow accumulation of snow on Antarctica will progress on a more "geologic" timescale. Implication: the Earth is analogous to an economic market: it generally "corrects" itself over time, but it sucks to be caught up in one of those corrections, whether a famine, drop in real estate value, or a rapid rise in sea level from Antarctic or Greenland ice falling into the sea. As the manager says in Bull Durham: "Think about that." Anyway, Mikey, keep up the good work down there. Look forward to seeing you next month at K-Weave's wedding. Got into a few schools and have a great story about Kenyon and I sleeping in the same bed in Montreal during his bachelor party. Remind me to pass those along. See you soon!

Anonymous said...

Saw the webcast! Now I understand what you're doing and have all kinds of questions! Easter time! How could you leave me hanging with "driving the tractor..." this is like a soap opera only I don't know when the programs on again. Hurry with lesson 2! And about the showers - seriously this is the first thing that's discussed when talking about you. Can't you divert some of that water from the drilling to the shower stall? I know you're shaking your head! :) Keep safe and warm!

Michelangelo said...

Hey Will. Thanks for replying, since I guess you're technically the Earth scientist here :) I do agree that catastrophic effects from climate change are probably a bigger worry than whatever will happen slowly over the course of time. I don't think that's the case with ice and sea level though. You can do a pretty simple calculation to see that.

Assume that roughly 70% of the Earth is covered in water. Also, for simplicity, assume that when you melt ice the resulting water takes up the same volume (in reality it takes up slightly less volume). One last assumption: assume the ice is as thick as it is at the South Pole, 2800 m. (It's nowhere near that thick near the coast when it goes into the water. It's maybe a tenth that thick). Then, to raise sea levels by, say, half a meter, which would be dramatic but not noticeable everywhere, you'd need around 25,000 square miles of ice to fall into the ocean all of a sudden. As a comparison, a few years ago a huge chunk of an ice shelf about the size of Rhode Island broke off catastrophically. This was all over the news. That was only about 1,200 square miles. Something about a hundred times bigger than that would have to break off, all of a sudden. And it would have to be ice that wasn't already floating on water. So I don't think a catastrophic rise in sea levels is all that likely...

wbain said...

Mikey: I think the term the young, inner-city kids would use is that I just "got served" by your response. All points you bring up are good, but allow me to clarify my "catastrophic" term. I think sea levels could rise dramatically (.5m would be dramatic) during the course of 50-100 years, which would require significant economic investment to overcome and would undoubtedly cause major changes to modern civilization. On the contrary, the slow accumulation of snow on Antarctica would proceed on more "geologic" timescales or thousands of years. Remember that ice ages in the most recent time period (Pleistocene) lasted between 40-100K years and it only took about 5K years for ice to retreat the last time it left. Point being that the accumulation of snow on the Antarctica is a negative feedback, but would be slow to dampen the positive feedbacks to global warming such as permafrost thawing and off-gassing, reduced albedo from sea ice melting, etc. Obviously, the issue of continental ice balance needs further investigation, but the fact is that the time for action starts now. Why? Because of the long residence time of CO2 in the atmosphere and the potential for dramatic positive feedbacks to warming--the CO2 contributions we are making today could be extremely difficult for our children and grand-children to mitigate. Finally, the really prominent changes in climate are already starting and have to do with biodiversity, etc. Why worry now? It takes me months to purchase a piece of equipment I have already budgeted for, etc.--therefore, its going to take decades to reduce our climatic impact when you consider the snail's pace of social, bureaucratic, and cultural change. What can you/we do about it? Find ways to sequester carbon (return from the atmosphere to the earth's crust) and do the things we should be doing anyway: reducing dependence on foreign oil and adding conservation measures and alternative energy redundancy to our critically-dependent oil economy, etc. There is no need to wear black Nike shoes or drink kool-aid in anticipation of armageddon, but we will have to deal with our fossil-fuel based society over the next century. I am stepping off my soap box with one final thought: I am really glad there are smart MFs like you in this world that are doing good things and pursuing the path of science!!! Look forward to seeing you next month. Smooches, Will

Michelangelo said...

Willis--I agree. Big changes in 50-100 years are definitely a concern. Those would be catastrophic and disruptive enough, even if they don't happen overnight. And you're absolutely right: there's no reason why we shouldn't get off of our asses and start to do something now.

One nitpicky point: snow accumulation does make a difference on short time scales. The latest paper I saw for Antarctica says that West Antarctica is losing ice at a rate of 132+-60 billion tons per year. East Antarctica 4+-61 billion tons a year. The uncertainties in East Antarctica are pretty bad and are mostly from accumulation. Taking the extreme case, WAIS could be losing ice at 72 billion tons a year and EAIS could be gaining it at 57 billion tons a year. That's a lot of accumulation...

Cautious Optimist said...

Whoa. Reading the back and forth between you and Will brought back memories of the night I had to listen to you, Nick, and Kovas discuss string theory at Sheffield's...

And Will, inner-city youth haven't told anyone they've been "served" since 2003. Finally, something I am an expert on...

wbain said...

Mikey: The real questions are:

1) Will the Economist or someone else pay you to write a science blog? I hope so. I met some young "woman" (censored blog and all) in Austin a few years back that wrote a blog and was underwritten by some conservative foundation (Cato perhaps?). It was abysmal--she showed me her Blackberry and I read some of her blogs. Pure comedy really--it wasn't my smoothest move ever to burst out laughing at her writing. Anyway, if they can pay some 23 year old to blather on about conservative dogma, you would hope that someone somewhere will pay a smart guy like you (that happens to look nearly 40 years old at the age of 28) to write an educational blog on science and as Ali G would say "tech-MOL-ogy." Think about that.

2) How could I be so poorly researched to not even look at snow accumulation rates? Good call on your part--I got served again.

3) How could Ann confuse me with someone else because there is no way in "heck" that I would be caught talking about string theory? That is for SERIOUS dorks, not just lazy, nasty pigs like myself. Ann--you just got served. Just like you, Nick, Mike, and I think Mel got served sour cream apricot scones the morning of my 21st birthday after I slept in the bathtub in a drunken stupor. Think about that.

Mikey: Aren't you supposed to be doing research down there? How is the ice cream machine? When are you coming home?

Anonymous said...

Hey you guys great comments. Ann always nice to see you keep in touch. Will, you know how much I enjoy you keeping Michelangelo on his toes!!!! Michelangelo havea safe trip back!! Remember this isthefinalfarewellto the SO Pole. Way a experience of a liefetime!!! LOVE YOU