October 20, 2013
Sea Level, on the Rise
Every once in a while, I do something that’s serious. Okay, often, I do something that’s serious. This is one of them. I played journalist a few weeks ago and interviewed Tad Pfeffer, a glaciologist at CU-Boulder, about the recently released IPCC’s Fifth Assessment Report. They’re somewhat few and far between, and this is the year. What do they tell us? The state of climate science and what we understand about climate past, present, and future—as best as we know at this time. I loved the process of doing the interview in the way that I first thought I would love doing journalism—I loved the learning. I learned as much as I could in the time I had allotted so I could actually conduct a somewhat intelligent interview with Pfeffer. That was the goal. Whether I accomplished it or not doesn’t really matter so much at this point, because I loved feeling like a journalist. And I learned about the IPCC report, knowledge that I can now build on moving forward.
[A once-flat, hundreds-of-meters thick Guyot glacier in Icy Bay, Alaska, now cracked as bedrock emerges in Guyot's rapid retreat. Had to use this image after I saw it was taken by a former co-worker, who was a PhD student of Pfeffer's. (Photo: Shad O'Neel, USGS)]
But enough about my process. Curious about sea level changes? Wondering when Miami is going to be gulping for air? We didn’t talk about the latter, but we did talk about some very interesting dynamics. Here are the most salient tidbits, and then you can read on if you want more:
- The International Panel on Climate Change (IPCC) is an intergovenmental body open to all members of the United Nations and the World Meteorological Organization. 195 countries are currently members. It doesn’t conduct research or collect new data, but rather “reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change.” (Straight from their website.)
- The IPCC has released reports in 1990, 1995, 2001, and 2007, and the full current report will be released in 2014. The reports consist of three parts from three working groups: physical science (climate past, present, and future), societal effects, and mitigation (both preventing and addressing the effects of human-induced climate change). At the end of September, the summary of the sciency part was released. The other two bits will (theoretically) build off that science.
- The recent IPCC Working Group I report consists of 14 chapters. Each chapter represents a major topic in climate science, with the exception of the introduction, and is authored by many scientists. This is not new research, but a summary of what’s out there.
- Tad Pfeffer was one of 14 lead authors on the chapter about sea level change.
- Sea level rise is accelerating. Global sea level increased an average of about 1.5 mm per year from 1901 through 1990, more or less. Then, from about 1993 to 2010, that rate went up to 3.2 millimeters per year.
- Current estimate have sea level rising between 26 to 98 centimeters by the end of the century (2100). The range is broad because what sea level does depends on what the climate does, which depends in part on what we do. Various scenarios are accounted for.
- Looking at the global mean sea level neglects local and regional effects. The sea surface is not uniform! It actually has topography that varies by up to two meters, or six feet.
- Small glaciers are the major contributors right now to sea level rise as far as water goes, even though the vast majority of ice on the planet is hoarded by the Greenland and Antarctic ice sheets. The contributions of these giants are catching up to the little guys. Total potential contribution breakdown: Antarctic ice sheet wins at about 70 meters of sea level rise (that's more than 210 feet), then Greenland with 7 meters, and then all the rest of the glaciers of the world with a whopping... half a meter. But half a meter matters, if you live in southern Florida. Or Bangladesh.
- The biggest contributor to sea level rise is not melting ice at all, but ocean expansion. As the ocean warms, it expands, like just about any other medium would.
- Did you know that the gravitational pull of ice sheets pulls sea level up locally? I didn't. So, when a big body of ice melts, there are two effects to consider: Sea level rise from the addition of water, and sea level drop from the loss of the mass of the ice on land.
Interest piqued? Read on (and see some cool graphics). Or, take a listen, if you’d rather, to the original interview, with full “um-ness” on KGNU’s How On Earth archives.
B: I'd like to start broad, talking about this report, and talk about the implications of the report--what does the report try to achieve, and what does it matter. Does it matter?
T: Yeah, it’s achieved I think two really worthwhile and remarkable things. One of them is to really solidify (...) what is happening with climate and sea level rise, the area I work in, and also [provide] better projections of what we expect to have happen in the future.
Our knowledge of warming and of the causes of warming has really evolved over the years. It’s really interesting. I was teaching at CU back in the early 90s, and at that time—so this is right around the release of the first IPCC report—what I was telling my classes was, you know, we’re almost positive that we can see a coherent warming signal in atmospheric temperatures. We’re not totally a hundred percent sure, but you know, a little bit more data, we’ll probably have it.
And then, a couple years later, I was saying okay, well now we know it’s warming, but we don’t really know why, and then it was, now we know it’s warming, and we’re pretty sure that it’s human-caused, but it was like the warming itself several years before. There wasn’t quite enough data to really know if it was us. And now, we really know it’s us. That’s one of the top conclusions of the Working Group I report.
And then, also, projecting forward into the future--and again, sea level’s the part that I really know about--we have better projections of where we think sea level is going to be by 2100, and that is, at the upper level of what we project, just shy of a meter, or about three feet.
B: Let’s get back to that in a second. Could you tell us more about your role in writing this report? Your role was as a lead author, one of fourteen lead authors on this chapter. What did it mean to be a lead author in this international collaboration?
T: Well, yeah, as you said, I’m a lead author, one of a group—each of the fourteen chapters in the Working Group I report has a group of lead authors, not all the same number—it’s on the order of a dozen--and then two coordinating lead authors which are sort of the, you know, orchestral conductors that tries to keep everybody pointing in the same direction. And we come into that group with various different kinds of relative expertise, and since the IPCC isn’t a body that does new science, that’s not our job—our job is to report on, synthesize, and make assessments of the existing science that’s out there—the lead authors need to have a broad awareness of what’s going on in their scientific community around them. And so for me, my job, if I had a specific task, was to represent the knowledge of what the smaller glaciers and ice caps around the world are doing. So this is all the ice in the world with the exception of the two big ice sheets on Greenland and Antarctica. And those [—the small glaciers—] have been the primary contributors of ice adding to sea level through the observational record up till now and will continue to be so through most of the 21st century. But the ice sheets are catching up rapidly. But that was really, that was my first job, was to be the person who knew what was going on with the glaciers and ice caps and contribute that knowledge to the group.
[A satellite image of Columbia glacier in Alaska, one of Pfeffer's field sites. NASA put together a beautiful series showing the glacier's retreat that's well worth checking out.]
B: Could you speak more to that? So your focus is on the glaciers, mainly in the Arctic, specifically in Alaska, and often when we think of big contributors to sea level rise, in terms of ice, we think of the Greenland ice sheet, we think of the Antarctic ice sheet—could you tell us more about what role these smaller glaciers that you study do play? You said they’re a major contributor, so—could you tell us how that works?
T: Yeah, yeah. The small glaciers of the world are—we don’t even really know how many there are, in part because you have to decide how small a glacier are you going to get to before you stop counting, but it’s on the order of maybe 200,000, something like that, and they’re very poorly observed, simply because there are so many of them. And they are a very large contributor of water to sea level rise right now, but at the same time, they’re a very small reservoir. In other words, their total potential for sea level rise is actually extremely low.
If you were to look at the relative sizes of the Antarctic ice sheet, the Greenland ice sheet, and everything else, the Antarctic ice sheet has something approaching, just using round numbers, 70 meters of sea level. More than 210 feet of sea level rise, if all the ice in Antarctica was to be put in the ocean. Greenland would have about 7 meters if it was put into the ocean. And everything else in the world, all of these other glaciers that I work on would only put in about half a meter. So, it’s a tiny, tiny reservoir, but as I said before, talking to some NASA people, the glaciers are like a little bucket with a huge hole in the bottom, because even though they’re such a small reservoir, they’re losing at a tremendous rate because there are so many of them, they’re so low in elevation compared to the ice sheets, and they’re in places where they’re affected first by climate change. So the actual contribution to sea level from the little glaciers has been greater than the combined contribution of the two ice sheets throughout the observational record up to now.
And now, the glaciers’ [contributions] are still a little bit more than the two ice sheets [contributions] together, but the ice sheets have been changing very rapidly. They’re accelerating. The glaciers are very noisy. They speed up for five years, they slow down—that is, their rate of contribution speed up and slows down—but it’s still a very important number to keep track of if you want to know what the total sea level rise is actually going to be. You can’t just focus on the biggest contribution or the contribution that has the potential to be biggest in the future, or the contribution that looks most interesting from a scientific perspective. If you want to produce a useful projection, you have to look at everything. And that includes these 200,000-odd glaciers, even though it’s a difficult task.
Me: And when we’re looking at contributors to sea level rise, we’re looking at the contribution of these smaller glaciers, the contribution of these ice sheets, but we’re also looking at ocean expansion due to warming. Could you explain a little bit about how that works, and how big of a contribution does ocean expansion have?
T: Yeah, that’s actually the largest single contributor, is thermal expansion. So, this is water expanding as it gets warmer. If you take a kettle and fill it right up to the brim, and put it on the stove, and turn the burner on, long before the kettle approaches boiling the water will start to spill out the top, and that’s because the density of the water actually drops. So the same mass takes up a larger volume as it warms up. And that’s happening in the ocean.
It happens mostly in the top layers of the ocean, because that’s where most of the heat from the warming atmosphere is going. So, then, modelers and oceanographers measuring thermal expansion look at it, they divide the ocean into the top 700 meters, which would be treated as a top layer, and then everything else below that, and most of the thermal expansion’s taking place in this top layer.
And of course, it’s not uniform globally because the ocean is warming at different rates. And that’s an important point to make about any of these global numbers that we talk about. Working Group 1 mostly, not entirely, but mostly talks about global averages. And all of these things have significant variations from one place to another, and that especially applies to sea level. The global rate of sea level rise has to be interpreted regionally, from one place to another. If you want to find out what’s going to happen to you if you live in San Francisco or London or Bangladesh, you can’t just look at the global average number. There’s a whole lot more going on local. Thermal expansion is one of those.
B: This is something that piqued my interest. In my naive view of the world, I think of the oceans as all one connected basin, but that’s not how it works.
T: Yeah, yeah—if you look at a map of the topography of the ocean surface, which we can do these days, with satellites that can measure the elevation of the ocean surface at very high resolution, it’s very lumpy. It’s not a nice, smooth dome, at all. And that lumpiness—these are vertical displacements on the order of a couple of meters. You know, six feet one way or another, over horizontal distances of tens of kilometers. When you’re going around in the ocean, you don’t see this. But if you look at a satellite image, it’s very, very pronounced, and it occurs because the water’s being pushed around by ocean currents, by winds, and also because mass on land is attracting water toward itself.
So, if you have a big mass sitting on land adjacent to the ocean, the ocean is going to feel the tug of this extra mass off to one side, and it’s going to pull the water toward it a little bit. And in calculating what sea level’s going to do in the future, it has to take that into account because there’s this very odd other effect of a shrinking ice sheet or a large glacier system where as that ice sheet shrinks in size, it’s gravitational attraction shrinks as well. So, a big Greenland ice sheet can pull a lot of water up around itself, and as the ice sheet shrinks, it does two things: It adds water to the ocean, which raises sea level, but also its gravitational attraction shrinks, and so in the vicinity of the ice sheets, sea level actually falls, for that reason, and you have to look at the sum of those two.
And so, as the Greenland ice sheet diminishes in size, or glaciers in Alaska diminish in size, sea level actually falls immediately adjacent to them, which is sort of counter-intuitive.
[Ocean surface topography from the TOPEX/Poseidon space mission in 1992. For more about measuring ocean surface topography, check out the GRACE website, or, learn more about data and images from NASA's TOPEX/Poseidon and Jason altimeters on their Ocean Surface Topography from Space page. (From Wikimedia Commons, via Wikipedia)]
B: Tad, let’s talk some numbers. You touched on it at the beginning of the interview—could you tell us a bit about the history of sea level change and what we’re looking at moving forward? You threw out the word “accelerating” in there.
T: Yeah. Sure. During the 20th Century, so 1900 up to the present more or less, we got really quite good measurements of global sea level rise. The rate of sea level rise was about a millimeter and a half per year. So that’s from, like, 1901 to 1990. But if you look at it much more recently, like 1993 to 2010, that rate has almost tripled. It’s gone up to 3.2 millimeters per year. And it’s not a smooth curve. It’s very choppy and jumpy and you have to average over pretty long time spans, more than a decade, to see those average rates. So you can find areas where sea level actually drops for a few years, then starts going up again. Five or six years ago or so there was a brief decline in the rate of sea level rise, and some skeptics were latching onto that (...), but you can find little patches like that in virtually any of these records, where if you look at a small enough time scale you can find the trend going in the opposite direction from the longer-term trend, but of course it’s the long-term trends that we all have to think about.
So, that was during the 20th century up to now, an increase from about one and a half millimeters per year over the entirety of the 20th century up to a little more than three millimeters per year over the last two decades or so. Incidentally, those numbers come from our tide gauge measurements earlier in that period of time, before we had satellites, so you were measuring the height of the ocean relative to a fixed point on land. But, of course, fixed points on land aren’t really fixed, because the land can go up and down, for a whole variety of reasons. And there’s a whole branch of science and geodesy in working out what those land motions are, because your reference point isn’t fixed, either. So using tide gauges is actually pretty complicated. And for many years, particularly in earlier times, there weren’t very many of them. So it’s hard to get a good global average.
Once satellites came in, it was possible to get a very comprehensive picture of sea level rise through satellite altimetry. So, the satellite is simply measuring the elevation of the sea surface, and this has all kinds of advantages, including the fact that you get coverage everywhere, not just along the coastline where you’ve installed the tide gauge. And also, you can get very dense spatial coverage across the oceans—that’s where you start to see the sea level topography. And also it can be done over and over and over again, so you get very high time resolution.
So that’s what the present looks like.
B: And moving forward…?
T: And moving forward, into the future, there’s an interesting story because, you know, we could talk for an hour about this by itself, because (...) We’ve been doing the sea level projections since the early 1970s. Essentially, since we had climate models that told us enough about what future atmospheric temperatures might do, we can start thinking about what the ocean might do as a consequence. But for the future, right now, the official IPCC projections range from about 26 cm up to just shy of a meter. 98 centimeters.
[The Southeastern U.S. sans what would be lost to one meter of sea level rise. (Screen shot from NASA's Climate Time Machine)]
B: Why is that range so big?
T: Okay, well there are two reasons for it. One of them is that we use a variety of different future forcing scenarios. In other words, what might climate do? That’s what is ultimately driving sea level. And if there’s uncertainty in what the atmosphere is gonna do, that carries right over into uncertainty in what sea level is gonna do. So we actually have five different future pathways for global temperature, and each one of those produces a slightly different range of sea level rise. But then, within each one of those scenarios, there’s a lot of uncertainty, and that’s because we don’t understand how the entire system works.
But the most volatile bit of the business of projecting sea level rise really lies in rapid ice dynamics, which is a fancy word that essentially boils down to calving of icebergs.
Glaciers and ice sheets that end in the ocean can get rid of ice much faster, much more efficiently, by calving icebergs, and that’s controlled primarily by how rapidly ice has moved down to the sea, to the perimeter of the ice where it ends in the ocean, and there’s a lot of complicated internal physics there, which we’ve made significant progress in since the last IPCC report, but it’s still kind of rudimentary. So, there’s a lot of uncertainty for that reason still.
B: So one of the main differences, and we might have to end on this point, but one of the main differences that’s been cited in the media between the last IPCC report, which was in 2007, so it’s been six years, and this year, is--a lot of people are talking about a difference in projected temperature range by the end of the century. Before, it was from a 2 to 4 degree Celsius increase, I believe, and now it’s 1.5 to 4, so that lower bound has lowered, the upper bound of potential temperature increase has stayed the same, but yet the sea level projections have gone up on their upper bound.
T: Yeah. Yeah. And that is because—well, again, the uncertainty is large compared to what uncertainty is, or, really, the change in the projection from that slightly lower bound on future warming. But also, it’s because this time, compared to AR4, we have the dynamics worked out more reliably. And this is the business of icebergs calving into the ocean rapidly. And that doesn’t depend very directly on temperature. That’s a process which is triggered by temperature, so warming can push glaciers and ice sheets into the state where they’re dumping icebergs like crazy into the ocean, but that rate of loss to iceberg calving doesn’t vary up and down with the temperature. So all of these processes that happen at the other end, the high end of the spectrum, don’t really care too much about the details of what the temperature is doing, as long as it’s pushing the ice system above this certain threshold.
Another thing that’s happening is we’re getting a better idea of what the small glaciers are doing.
And that's where we had to cut it off, for want of time. End. Didn't get to my questions about any difficulties in building consensus, which is required for the report, or the effects of the sea level rise. The latter can easily be explored on the Web, although I swear that there was a great tool for looking at sea level rise that I just can't for the life of me find. The ones that came up were all too geographically limited, too rough of a scale, or just plain ugly. Sigh. Explore. Let me know what you find.
Sea level. It's coming up.
October 15, 2013
What's Up Down South
This is the iceblog, after all.
The effect of the government shutdown on research in Antarctica has made it to the news, but of course can't get to the full extent of what's happening. I can't, either, but at least I can maybe offer up a little extra insight, since I'm still in touch with lots of ice friends. And regardless, I feel like I need to comment on it here.
First, some basic facts, as far as I know them:
- Why is the Antarctic Program affected by the shutdown?
The U.S. Antarctic Program is run by the National Science Foundation (NSF), which is part of the government. Services are provided by Lockheed Martin, which is affected by the government shutdown by way of funding (because they are funded for this work by the NSF, which is shut down).
- Why does it matter that the shutdown is *now*?
In a nutshell: Tis the season! The Antarctic sun is coming up and this is when things down there get cranking.
There are three work seasons for McMurdo Station, by far the biggest of the three US stations down there: winter (Feb - Aug, no flights), winfly (Aug - Sept, minimal flights), and main body (Oct - Feb, lots of flights and projects and research, plus flights in and out of the South Pole Station). We're right at the beginning of "main body," the time window when everything really happens down there. Folks were starting to head down when the shutdown occurred.
- What's the current status of the Antarctic season?
The NSF ordered the Antarctic program into "caretaker status" last week, meaning it's going down to a skeleton crew that can maintain only essential activities on stations.
The program has started sending people back. People were turned back in Los Angeles and in Christchurch, New Zealand, on their way down to the Ice. They have also started shipping folks out of Antarctica. Some personnel deemed essential will still be heading down. Many people are waiting to see what will happen. This applies to both researchers and contractors.
Some (much?) of the season will hopefully be salvaged, and hopefully sooner than later (come on, government), but the season is already not normal.
Now this is the stuff that's non-factual, and things that I'm curious about as well.
- How will research be affected?
Long-term data sets are going to be missing data points. (Big data points--I don't mean to minimize their importance. And data points that can only be collected in this one time window.)
Some friends and I are concerned in particular, though, about shorter projects, that only have two to three years to collect data, and about grad students that are counting on timely data collection for the timely completions of their degrees.
- What are the other effects?
The Antarctic stations are run by contractors. Many of these employees are seasonal, and this is not only their adventure (mostly for the first-timers) and their family (a community forms and bonds over the years), but their primary source of income for the year. Many of these employees are now finding themselves without a job. (BTW--There are grassroots job and housing boards springing up for Ice folks, by Ice alumni.) Also, this means, should the NSF try to ramp the season back up, much of their workforce will likely have dispersed.
So, as touched on the in NYTimes article linked below, it's more than just scientists who are affected (the NYTimes says 3,000 Americans work through the Antarctic summer--that includes scientists and support staff).
For more, here's what else the Times has to say today:
The best resource would probably be the reporter for the Antarctic Sun, but unfortunately he's not allowed to post anything... because the NSF runs the webpage... and, right, they're shut down...
October 14, 2013
Fall Up Lost Angel
Yeah, she's cute.
I hopped up to Lost Angel Road, up in the foothills outside Boulder, to hang out with her and her mom, Laurie, this weekend. Come up today, Laurie said on Saturday, because it's supposed to be windy tomorrow.
So we bundled up on what was really more of a winter day than a fall day and went for a short but lovely hike.
I was planning to head back that afternoon or evening, but thought better of it when Laurie and her hubby, Tim, invited me to stay the night. Mostly it was great because Laurie turned out to be wrong about Sunday's weather.
October 10, 2013
I was having a bad day, so what did I do? I colored.
I didn't realize until I was almost done that I was coloring. You know, classic coloring, like a kid would do. Here, kid, dry your tears, here're some crayons.
Okay, and it's a crappy piece of "art," but there are some nice elements to it, and it was just for fun, anyway. As far as what it is... I dunno, some vague semblance of water, rocks, grass, weird sky. I'd say they're not the colors I'd choose, but I'm pretty sure I chose them. To my credit, the room was pretty dark when I got started.
What do you do when you have a bad day?
October 5, 2013
I love Facebook.
It's annoying, too, but mainly I love it, and here are two reasons why, just from this week:
1) I wanted to say on our radio show on Tuesday that many (most?) scientific organizations suffered funding cuts for this coming year. It was meant to be a sort of "welcome to the next fiscal year, in the world of science" comment, and I knew UNAVCO has experienced a substantial cut in funding, and *assumed* that other orgs faced the same fate. But I didn't actually know. So, I put it out to Facebook. Crowdsourcing is the bomb. The responses from my sciency friends—a journalist, an NSF employee, a researcher and a field tech/engineer—showed the answer is more complicated than I could sum up in one statement, and I abandoned it. Lazy journalism or resourcefulness?
2) I saw a friend was listening to a bunch of Violent Femmes on Spotify (another great Internet tool) and shortly thereafter spotted my Cake CD (yep, still got some of those) on the floor of my room and thought yeah, I'm in the mood for something kind of quirky and fun. But I'm also in the mood for a female vocalist. !? Wait, what? Does that combination exist? Here's what I put out to Facebook:
Huh... are there any quirky / funny female bands out there? Or do all female bands take themselves seriously? I'm thinking Violent Femmes, Cake... is there not a market for quirky women, or am I just drawing a blank? Kimya Dawson is the only one who's coming to mind.
This is exactly the kind of query Facebookers love.
Here are the responses, in case you're curious:
The Ditty Bops
Lake Street Dive
Regina Spektor (esp. Soviet Kitsch or Songs
KT Tunsall (song: Ashes)
Now... I think most of, or many, of these are, say, spunky or sassy but not so sure about quirky and silly, or not taking themselves seriously. Some, though, yes, and all deserve a listen. I'm making my way through them on—yes—Spotify. Please, please, add to this list.
(My favorite comment, by the way, was "Cat power doesn't take herself too seriously....")
I might want to write a short piece on this, so by all means, if you have thoughts on this, please comment here, or e-mail me and rant, or find me on Facebook and rant, or whatever.
[October 10, 2013
Christine Lavin ("is hilarious!! She has a song about an amoeba band in a mud puddle!")
Garfunkel and Oates
And, here's an article recommendation from my friend Nichole, which is worth clicking just for the pic with it. Awesome:
Me 'n' the Gov'mnt
So, we were told—I was told, or I heard somewhere along the line—that UNAVCO, where I'm working as a "temporary" employee these days, would not be affected by the government shutdown. Indeed, UNAVCO is not a government organization. But we are, like so many other organizations not represented in articles and infographics, funded by the government. Most of UNAVCO's funding comes from the National Science Foundation (NSF), with a much smaller chunk from NASA and an even smaller chunk from other sources. I don't know how the money distribution works, but apparently we don't just have a wad of cash from NSF to spend for the year (or the next five, which is what our grant is for). Perhaps we would have if it weren't at the beginning of the fiscal year. Either way, I'm cut off from hours until the government cranks on that lever and starts up the lights again.
I'm cut off because the decision was made (passive, because I don't know who made it and there's no reason to point fingers) to shut down funds to temporary employees, in addition to some other funding cuts. I was feeling maybe a little picked on (I mean, how much of their budget do I really take?) until an e-mail just came out reporting even more drastic measures: Salary cuts across the organization to keep UNAVCO running, at least for a bit. A salary cut that's not so much to cough at, for some. The org assures that this cut is in place "with the intent to restore retro pay when federal funds become accessible," which sounds just a little tenuous to me. Regardless, UNAVCO is taking one for the team. Whatever that means.
Also, the Antarctic season is in jeopardy. Right now is when everyone is heading south—or planning to. If you're not already down there... Well, hope you make it.