Daily Archives: July 23, 2013

Important New Science on Melting Glaciers

Most of the current models of glacial ice melting (and contribution to sea level rise) focus on ice melting and less than they need to on the process of glaciers falling apart in larger chunks such as ice bergs. Also, current understanding of glacial ice melting due to global warming indicates that the Western Antarctic Ice Sheet (WAIS) is more vulnerable to melting over coming decades or centuries than is the Eastern Antarctic Ice Sheet (EAIS). New research from two different teams seems to provide a major corrective to these assumptions.

First, about how glaciers turn into ocean water.

ResearchBlogging.orgConsider this experiment. Take a large open-top drum of water and poke a hole near the bottom. Measure the rate at which water comes out of the hole. As the amount of water in the drum goes down, the rate of flow out of the hole will normally decrease because the amount of water pressure behind the hole decreases. Now, have a look at a traditional hourglass, where sand runs from an upper chamber which slowly empties into a lower chamber which slowly fills. If you measure the rate of sand flow through the connecting hole, does it decrease in flow rate because there is, over time, less sand in the upper chamber? I’ll save you the trouble of carrying out the experiment. No, it does not. This is because the movement of sand from the upper to lower parts of an hourglass is an entirely different kind of phenomenon than the flow of water out of the drum. The former is a matter of granular material dynamics, the latter of fluid dynamics.

Jeremy Bassis and Suzanne Jacobs have recently published a study that looks at glacial ice as a granular material, modeling the ice as clumped together ice boulders that interact with each other either by sticking together or, over time, coming apart at fracture lines. This is important because, according to Bassis, about half of the water that continental glaciers provide to the ocean comes in the form of ice melting (with the water running off) but the other half consists of large chunks (icebergs) that come off in a manner that has been very hard to model. By treating the ice as a granular substance, Bassis and Jacobs have been able to look at the relationship between the large scale geometry of glacial ice and the smaller scale process of ice berg calving.

From the abstract of their paper:

…calving is a complex process and previous models of the phenomenon have not reproduced the diverse patterns of iceberg calving observed in nature… Our model treats glacier ice as a granular material made of interacting boulders of ice that are bonded together. Simulations suggest that different calving regimes are controlled by glacier geometry, which controls the stress state within the glacier. We also find that calving is a two- stage process that requires both ice fracture and transport of detached icebergs away from the calving front. … as a result, rapid iceberg discharge is possible in regions where highly crevassed glaciers are grounded deep beneath sea level, indicating portions of Greenland and Antarctica that may be vulnerable to rapid ice loss through catastrophic disintegration.

ResearchBlogging.orgThis is interesting in light of a second recent paper, by Carys Cook and a cast of dozens, which looks at Antarctica during the Pliocene. Green house gas levels were about the same during much of the Pliocene as the current elevated levels, and sea levels may have been many meters higher at various points in time as well. From the abstract of that paper:

Warm intervals within the Pliocene epoch (5.33–2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century and atmospheric CO2 concentrations similar to today. Estimates for global sea level highstands during these times imply possible retreat of the East Antarctic ice sheet, but ice-proximal evidence from the Antarctic margin is scarce. Here we present new data from Pliocene marine sediments recovered offshore of Adélie Land, East Antarctica… Sedimentary sequences deposited between 5.3 and 3.3 million years ago indicate increases in Southern Ocean surface water productivity, associated with elevated circum-Antarctic temperatures. The [geochemistry]… suggests active erosion of continental bedrock from within the Wilkes Subglacial Basin, an area today buried beneath the East Antarctic ice sheet. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East Antarctic ice sheet was sensitive to climatic warmth during the Pliocene.

This is, to me, one of the most disturbing facts about climate change that we learn from the paleo record. It may be reasonable to say that our near doubling of greenhouse gasses have brought us to a situation in which it is normal to have perhaps something like 20 meters more sea level than we have today, and that the only thing keeping that from happening is … well, nothing, really, other than time. Glaciers tend to behave glacially, after all. Cook et al. look at sediments offshore from Antarctica deposited during the Pliocene periods. Using fingerprinting with specific stable isotopes they were able to determine that at certain times during the Pliocene sediments were being deposited in the ocean from an eroding landscape that is currently deeply and firmly buried under the EAIS. This seems to suggest that under conditions not necessarily very different from today, large areas of Eastern Antarctic, thought to be iced over long term, can be ice-free. If those vast areas were ice free, than the ocean would have been much higher, and it seems that the ocean was, in fact, higher at that time.

I asked Jeremy Bassis, lead author of the ice-as-granular-material paper, if he could translate the modeling work done by him and Jacobs into an estimate of how fast glaciers could disintegrate. He told me that it was hard to say. Their models help them “… understand the different patterns of calving that occur and based on that, it looks like some regions of Antarctica and Greenland might be vulnerable to disintegration. However, the simulations we did took place over a few hours so to translate that into an actual sea level rise estimate we would need to run the models for much longer. The best I can say for sure is that based on our model, important processes are not included in current estimates of sea level rise.” He also noted that most models that don’t use paleo data assume iceberg calving at present rates from their current position at the sea. Their paper, however, suggests that these may not be good assumptions.

Sadly, none of this work will be included in the upcoming IPCC reports. The time cycle for IPCC is rather ponderous, which may be good in some ways, but also has disadvantages. These two papers exemplify an effort to address one of the biggest unknowns in climate change, the nature and character of meltdown of the polar ice caps. We need to put more resources into this sort of study.

Meanwhile, don’t throw away your knickers.

Bassis, J. N., & Jacobs, S. (2013). Diverse calving patterns linked to glacier geometry Nature Geoscience DOI: 10.1038/ngeo1887

Cook, Carys, Flierdt, Tina van de, Williams, Trevor, & et al (2013). Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth Nature Geoscience DOI: 10.1038/ngeo1889

Levees and the National Flood Insurance Program (NAP)

The National Academies Press of the United States has recently released a report that will be of interest to those of you concerned with climate change (which better be every one of you dammit!). The report talks about increasing floods due to weather whiplash and sea level rise due to glacial melting (and subsidence), mainly in relation to the levees program and insurance, but also more generally. Here’s a small excerpt to give you a flavor:

Community flood risk scenarios will continue to evolve as change occurs. Climate change will have a variety of regional impacts, and the geographic location of a community will affect how changing conditions affect risk. Some areas will have more droughts, some will have more frequent floods, and others will have more intense floods. Research to understand these hydrologic changes is ongoing (NRC, 2011, 2012a). A recent special report of the Intergovernmental Panel on Climate Change (IPCC, 2012) indicates a likely increase in many regions of the frequency of heavy precipitation events, and when coupled with increasing vulnerability presents a myriad of challenges for coping with climate-related disastersIPCC. Galloway (2009) cites 11 major international studies conducted from 1987 to 2002 that all predict significant climate change–induced hazards, including increased flooding, higher mean atmospheric temperatures, higher global mean sea levels, increased precipitation, increased strength of storms, more energetic waves, storm surges that reach further inland, undercapacity of urban sewer- age and drainage systems, increased vulnerability of port cities, and disproportionate impacts on disadvantaged population segments (Galloway, 2009). The rise in sea level and the increase in storm surge due to climate change puts many coastal areas at risk from intensified flooding (NRC, 2010).

Hirsch and Ryberg (2012), in examining trends in annual floods at 200 stream-gauge sites in the United States, found that , while there appeared to be no strong statistical evidence for flood magnitudes increasing with increasing global mean carbon dioxide concentration, there were differences in flood magnitudes among the four quadrants of the conterminous United States (Figure 6-8). They indicate that the attention should be paid to the effects of changes in the relative “importance of the role of snowpack and rain on snow events.” Raff (2013) suggests that the increase in magnitude of floods in the northeastern and midwestern United States (Figure 6-9, Upper Right), may have consequences in the Upper Mississippi, Ohio, and Missouri watersheds (Hirsch and Ryberg, 2012; Raff, 2013).

The Draft National Climate Assessment, issued in January 2013 by the National Climate Assessment Develop- ment Advisory Committee, begins with the statement:

Climate change is already affecting the American people. Certain types of weather events have become more frequent and/or intense, including heat waves, heavy downpours, and, in some regions, floods and droughts. . . . The largest increases have occurred in the Northeast, Midwest, and Great Plains, where heavy downpours have exceeded the capacity of infrastructure such as storm drains, and have led to flooding events and accelerated erosion.

The report goes on to point out the increasing vulnerability to flooding of those in floodplains and coastal areas

You can buy the report for a mere $53, or download it for free. (Downloading from the NAP involves signing in and stuff, but it is pretty easy, though at the moment their server is running a bit slow since they just publicized the report and everybody wants a copy of it.)

Go HERE to get the report.

James Hansen on Nuclear Power

James Hansen, the famous climate scientist and author of Storms of my Grandchildren, talks about the possible role of nuclear power in addressing climate change, and in particular, reducing the release of fossil carbon into the atmosphere.

I think he is far to pessimistic on the use of solar and wind energy than he needs to be and notice that he, and no one else ever, seems to mention geothermal, which could reduce our release of carbon by double digit percentages using existing technology in a few years. Having said that, there is probably no way to solve our energy problem without implementing next generation nuclear power to some degree.

Photo Credit: u? via Compfight cc

RIP Hobbit Finder Mike Morwood

From The Australian

THE Gandalf of science, archeologist Mike Morwood, who helped find a new species of tiny humans dubbed the Hobbit, died yesterday after a year-long battle with cancer.

Professor Morwood’s legacy will be linked to the Indonesian island of Flores, where in 2003 he was part of a team that discovered Homo floresiensis, which rewrote the history books and changed our understanding of human evolution….

There is nothing wrong with Tsarnaev’s face

Does this picture of Hitler make you like him?
Does this picture of Hitler make you like him?
I dislike Dzhokhar Tsarnaev’s, that dislike contingent on his guilt yet to be proven (but very likely, it seems). His picture on the cover of Rolling Stone makes a point that struck me during the mayhem in Boston, and it is a good point. Those who reacted to this photograph negatively are seeing this situation in the first order, missing the point, missing the nuance. They are operating at the bodice-ripping romance novel level of thinking, not even the semi-complex Hercule Poirot level, of thinking. The Commonwealth of Massachusetts cop who released the “real” pictures of Tsarnaev violated the rules of his job, and he’ll presumably take some heat for that (though I couldn’t possibly care less about that) but more importantly he acted poorly and in a way that sets us back, as a country, in our thinking about terrorism.

Hitler never grew out of his Terrible Twos, apparently
Hitler never grew out of his Terrible Twos, apparently
Consider Adolf Hitler. I went looking on Google Images for a picture of Adolf Hitler to see if I could find a picture in which he didn’t look like the absolute monster that he was. There were a few photos of him chatting with his fellow monsters, uniformed, being Nazis, but they weren’t very good photos. I found a picture of him as a toddler and a picture of him wearing bunny ears (which I assume is a fake, but do correct me if I’m wrong because that would be interesting). But only the toddler picture counts. Yes, folks, any toddler could ultimately become Adolf Hitler (probably by never growing out of the Terrible Twos, but that’s another story.) And yes, Dzhokhar Tsarnaev could be anybody.

My daughter, just a bit younger than the Tsarnaev brothers, headed off to Boston one day and was actually in the air not yet landed at Logan when the bombs went off at the marathon. For the entire day, I kept in touch with her via text messaging. She and her mom made it to their hotel in South Boston after hackney services were restored, though they had to spend a fair amount of time in the airport first. Over the next couple of days, the drama we all know about unfolded.

This perfectly nice looking guy is on trial in Boston, right now, for some 17 murders (and more).
This perfectly nice looking guy is on trial in Boston, right now, for some 17 murders (and more).
Somewhere during this time, Julia noted that had she been in the same high school with the Tsarnaev’s, she’d probably be their friends. This is not because she hangs around with terrorists. Rather, she has a long history, since early childhood, of association with the part of the world they come from, having lived in west/central Asia and gone to school there. Also, she lived in a country that, like Tsarnaev’s native land, was oppressed by the Soviets and since by the Russians. There would be many connections between them and they’d probably attend each other’s graduation parties. When I heard about the Rolling Stone cover, I thought of that, and thought it important to make the point that the Tsarnaevs are American Terrorists and emerged from our culture just as much as form somewhere else (though obviously it is more complicated than that).

We live in a culture where the visual trope rules. If a famous beauty is found by photographers with tussled hair, cellulite, or some food spilled on her shirt, that’s news. If a teabagger wants to depict Obama as a bad guy, he darkens the image because that racist trick works on a lot of people. They say (though I don’t assume it to be true) that Kennedy beat Nixon because Nixon had a bad five o’clock shadow. And so on. Massachusetts Trooper Sgt. Sean Murphy saw a picture of a bad guy that didn’t make him look like a bad guy and felt the need to risk his own career and violate the rules of his job, and probably violate his profession’s ethics, in order to “correct” that so the rest of us could go on hating Tsarnaev properly. He was wrong to do that. Nobody decided that it was OK to blow up people at the Boston Marathon because Tsarnaev looks like a hipster when he’s not all shot up lying in a boat in Watertown.

Also, this: If we insist that how you look has to match what you do, what you’ve done, what you might do, the kind of person you are, then we are fully subscribing to the worst in human nature. Think about it. If you are a woman and you wear certain cloths … If you have a certain color skin … If you seem to have a certain expression on your face …

Get over it, people. There is nothing wrong with Tsarnaev’s face. There is something wrong with Tsarnaev. These things are both true. Embrace the complexity that is reality.