| Topsy-Turvy Science: A Personal Narrative of a Half-Century in Science
Dr. Terence J. Hughes My scientific career can be understood as postulating a number of theoretical mechanisms that might operate on scales ranging from local to global. Some ideas never took hold. Others did, after a lag of 10, 20, 30, and more years. Few if any took hold immediately. That is because most proposed interpretations were directly contrary to the prevailing wisdom. Hence, they propose topsy-turvy science. 1960-1968 1968-1972 In 1971, the Journal of Applied Physics published my paper pointing out that thermal convection in polar ice sheets would be a model for thermal convection in Earth’s mantle. If ice-sheet convection were confirmed, the Antarctic Ice Sheet could be treated as a simplified (one crystal structure) miniature mantle accessible by deep drilling that could be used to study thermal convection in Earth's inaccessible mantle that moves Wilson's crustal tectonic plates and causes continental drift. That would make it my most important idea by far, and it would be a great boon to glaciology. It's my only idea that has merited Invited Paper status, in 1975, at a Symposium on the Thermal Regime of Glaciers and Ice Sheets sponsored by the International Glaciological Society. Nobody has asked for a reprint of my paper. Convection moves ice upward, which is topsy-turvy. In 1972, the Journal of Applied Physics published my derivation of the Rayleigh number needed to initiate thermal convection in crystalline materials like ice sheets. The middle third of the Antarctic Ice Sheet is heavier than the bottom third because it is colder. That makes it an enormous reservoir of gravitational potential energy poised for release as gravitational motion not considered in conventional glaciology. The Rayleigh criterion for initiating thermal convection in viscous fluids is satisfied, when modified for convection in viscoplastic crystalline solids, ice specifically. Viscoplastic deformation begins as transient creep, which starts with an infinite strain rate that gives a Rayleigh number infinitely above the critical Rayleigh number for initiating thermal convection in the Antarctic Ice Sheet. Only as slow steady-state creep sets in can the Rayleigh number drop below the critical value in some parts of the ice sheet. It other parts it stays higher and recrystallization of ice in the bottom third allows fast steady-state creep, so the Rayleigh number can climb once again. But intermittent transient thermal convection should always be possible. So why doesn’t the cold ice ceiling collapse into the warm ice basement? If it did, would collapse be catastrophic? Everywhere at once? What then would be the implications for thermal convection in Earth’s crystalline mantle, and for plate tectonics in Earth’s lithosphere? These questions are important. For me, the question is not whether ice-sheet convection occurs, but how? I see it in ice streams, perhaps even causing ice streams, as reported in the Journal of Glaciology. In 1976 I wondered if ice streams were warmer than adjacent ice, so they were “buoyed up” enough for basal water to flow in and uncouple ice from the bed, allowing stream flow. By 1992 I argued that stream flow begins when the cold ice ceiling collapses into the warm arm ice basement in directions of ice-sheet spreading, creating the concave longitudinal and transverse profiles that characterize ice streams. Basal water driven toward lowered ice by the hydrostatic pressure gradient might uncouple ice from the bed enough to initiate stream flow. Some displaced basement ice might rise in the lateral shear zones and join ice flowing toward the lowered ice from the sides. Warm basement ice displaced downstream carries the cold sinking ice in extending flow, producing transverse surface crevasses. Ice advected downstream never completes a convection “circuit” but ninety percent of Antarctic ice is discharged by ice streams, so most of the gravitational potential energy stored in the cold ice ceiling is released as kinetic energy by the motion of ice streams. Alternatively, ice streams could form by other processes and stream flow then allows this kind of thermal convection. This chicken-or-egg question has two answers, topsy and turvy. Either way, this release of gravitational potential energy is not considered in theories of ice streams. I’m working on it. 1972-1975 In 1973, I attended the Second International Conference on Permafrost, held in Yakutsk, Siberia. There I presented a paper holding that much of the arctic permafrost in Siberia and Canada originated as the debris-charged basal layer of Quaternary ice sheets. This was published by the National Academy of Sciences in 1973. Since then, studies at various sites have confirmed this origin. Conventional wisdom is that permafrost formed from the top down after the ice sheets were gone, which is often the case. But when it formed from the bottom up as basal debris-charged glacial ice, that’s topsy-turvy. In 1974, a Symposium on Andean and Antarctica Volcanological Problems published field studies from my first Antarctic research proposal funded by NSF, a study of ice flow and calving dynamics into a crater produced by the 12 August 1970 volcanic eruption on Deception Island. This began a long collaboration with Henry Brecher in Antarctica and Greenland. It also began my theoretical research on the mechanisms for calving of ice slabs from ice walls and tabular icebergs from ice shelves that has continued for three decades. It was the first such study in a new branch of glaciology that is now expanding rapidly because, in recent years, massive calving events have occurred all along the Antarctic Peninsula (south of Deception Island), and all along the Ross Sea, Amundsen Sea, and Weddell Sea flanks of the West Antarctic Ice Sheet. I think this accelerated calving may be an "early warning system" heralding further collapse of the West Antarctic Ice Sheet. But that’s topsy-turvy if so many calving events were a coincidence. I spent the last six months of 1974 at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, as a Senior Postdoctoral Fellow in the Advanced Study Program. This came about because I had been part of a committee that established an Atmospheric Science Program at The Ohio State University that made OSU faculty eligible for this appointment. I was the first to apply, and was accepted. There I wrote my third ISCAP bulletin. Bev Barr married me in June, so it was also our honeymoon. In 1975, Palaeogeography, Palaeoclimatology, Palaeoecology (Palaeo-3) published what is still my paper getting the most requests for reprints by far: “The case for creation of the North Pacific Ocean during the Mesozoic Era.” It postulated a migrating tetrahedral pattern of mantle convection that split cordilleran North America from East Asia during the late Paleozoic, transported it across the North Pacific during the Mesozoic, and welded it onto cratonic North America during the Cenozoic. That same year, geologists published papers showing that cordilleran North America is a collection of allochthonous terranes having no relation to East Asia. My most popular idea was topsy-turvy and dead-on-arrival. However, it got me on the Palaeo-3 editorial board for 23 years, and an invitation from the Institute of Physics in Bristol to write a book on the tectonic history of the Pacific basin. My idea for the tectonic history was to present two competing hypothesis for the Pacific basin, the newly emerging plate tectonics and an earlier hypothesis by S. Warren Carey that Earth was expanding. Early observations were compatible with both views as was my migrating tetrahedral pattern of mantle convection, which I had developed in two papers published in Tectonophysics in 1973. I invited Sam Carey to the University of Maine to give a lecture, The Expanding Earth, on 23 April 1984. By then plate tectonics had “won” and, not wanting a second dead-on-arrival publication, I finished the book and kept it for historical interest only, with a copy to Sam Carey. He died in 2002, at age 90. 1975-1980 We presented two reconstructions of former Northern Hemisphere ice sheets, a minimum model in which ice sheets ended near present-day shorelines and a maximum model in which these ice sheets extended to the edge of arctic and sub-arctic continental shelves. The two models were based on different interpretations of so-called "weathering zones" along fjordland coastlines of North America and Europe. The conventional view was that these zones represented former ice-sheet surface elevations existing at different times during Quaternary glaciation cycles. After observing them on the Gaspe Peninsula of Quebec, I concluded they were basal thermal zones produced under the ice sheets during the last glacial maximum, zones in which the bed was either frozen, thawed, or a mosaic of frozen and thawed patches. It was topsy-turvy from the prevailing view. I developed a "bottom up" scheme for reconstructing former ice sheets to produce two models, based on the two interpretations of "weathering zones" and of glacial geology in general. My “bottom-up” approach was topsy-turvy from the conventional "top down" approach that relied on reconstructing former ice sheets based on a specified (but largely unknown) mass-balance pattern of ice accumulation and ablation rates over ice-sheet surfaces. Top-down models produced patterns of basal frozen and thawed regions, and therefore variations in basal traction, that were extremely sensitive to the surface mass balance. Small mass-balance variations resulted in big differences in ice elevations calculated from bed traction. My bottom-up approach was insensitive to the surface mass balance, being based on the idea that glacial geology revealed where the bed was frozen and thawed, providing more (frozen bed) or less (thawed bed) traction that required higher or lower ice to overcome the basal resistance to flow. Our “maximum” and “minimum” models, both based on the bottom-up approach, spurred an ongoing search for the "marine" ice sheets on continental shelves generated in the maximum model. The maximum model won out when exposure-age dating techniques were developed and applied to date glacial erratics and exposed bedrock in the fjordlands. In 1977, I began a three-decade collaboration with Mikhail (Misha) Grosswald of the Institute of Geography, USSR (now Russian) Academy of Sciences, in Moscow. Misha, George Denton and I took an idea from John Mercer in 1970 and postulated in Nature that a single “Arctic Ice Sheet” behaving as a unified dynamic system existed at the last glacial maximum. It had an ice shelf floating in its center and it disintegrated from the inside out. This was topsy-turvy from the ice-free Arctic Ocean proposed by Maurice Ewing and William Donn in Science from 1956 to 1966. In 1968, Misha, along with Swedish and Canadian colleagues Valter Schytt, Gunnar Hoppe, and Weston Blake, had proposed a marine ice sheet in the Barents Sea north of Scandinavia. In 1970, Blake showed that a marine “Innuitian Ice Sheet” had also covered the Canadian Queen Elizabeth Islands. Since then, Misha found evidence for a marine “Eurasian Ice Sheet” extending from Spitzbergen to Alaska that transgressed onto the Russian mainland from the arctic continental shelf. I reconstructed its vertical elevation, based on his glacial geology. This has triggered ongoing fieldwork in the Eurasian Arctic that has confirmed a former marine ice sheet in the Chukchi Sea and a thick ice shelf in the Arctic Ocean. The ice shelf, these marine ice sheets, and their landward extensions were an Arctic Ice Sheet. Resistance to our ideas about vast former ice sheets in the Arctic inspired my 1980 letter in Boreas, “Genes and glacial history.” I floated the topsy-turvy idea that resistance was based on genetics, not field evidence. During the last glaciation, some Europeans adapted to the advancing ice sheets whereas others fled to Africa. After the ice sheets were gone, they came seeping back into Europe and mingled with those who toughed it out. Today, genetic recombinations replicate both types in certain individuals. Misha and I have the genes of those who grew to Love The Ice. As for the others, they can’t stand ice anywhere. They barely tolerate half-vast ice sheets, and we all know Who They Are. In 1980, I concluded my forays into plate tectonics after I was invited to attend the International Conference on Mathematical Problems of the Thermal and Dynamic State of the Earth held at Lake Arrowhead in California. There I met all the "heavy lifters" in plate tectonics and mantle dynamics. I presented a theoretical model for thermal convection in Earth's mantle that turned on and off when the thermal buoyancy stress rose above and fell below a "yield stress" for crystalline mantle rocks, with narrow hot curtains rising rapidly under plate boundaries and broad cold plugs sinking slowly under the plates. That's where I met Dick Peltier, who had developed models of mantle viscosity based on rates of post glacial crustal adjustments to the changing distribution of ice and water on Earth's surface since the last glacial maximum. We both argued for mantle-wide convection. I wrote a paper on lithosphere deformation by continental ice sheets, using my viscoplastic yield stress criterion, which was topsy-turvy from viscous deformation. The Royal Society of London published it in 1981 in its Proceedings. 1980-1992 In 1986, I proposed the "Jakobshavn Effect" after several trips with the U.S. Coast Guard to study calving of giant icebergs from Jakobshavn Isbrae in West Greenland. It has long been the fastest ice stream on Earth and it drains about eight percent of the Greenland Ice sheet. The Jakobshavn Effect combines disintegration of a buttressing ice shelf floating in Jakobshavn Isfjord with ice-bed uncoupling resulting from surface meltwater reaching the bed through crevasses in the ice stream. The result would be rapid downdraw of interior ice caused by a sequence of positive feedback mechanisms. Both unbuttressing and uncoupling were reported in 2002 by NASA glaciologists. Since then several other large Greenland ice streams have begun showing the same behavior, all doubling their velocity, some within a year. That confined and pinned ice shelves could buttress ice streams was a topsy-turvy idea I put in my first ISCAP bulletin in 1972. The objection was, “How could ice at the end of the line affect what went on earlier?” In 1987, I proposed "The Marine Ice Transgression Hypothesis" (MITH) in Geografiska Annaler to account for paleo-shorelines and oxygen-isotope records showing that descent into a Quaternary glaciation cycle was as rapid as its end. These cycles end so fast they are called Terminations. Many mechanisms have been proposed to account for Terminations (I've published a few myself), but none account for the rapid start. In the traditional view, ice fields on highlands move into lowlands and then cross shallow marine embayments like Hudson Bay and the Baltic Sea to become the respective Laurentide and Scandinavian ice sheets. When ice caps on arctic islands such as in the Spitzbergen archipelago reach shallow seas today, however, they end as calving ice walls grounded in water. They aren’t big enough to lower sea level so they can advance on land, nor were former ice caps. In MITH, sea ice thickens into an ice shelf, so the calved ice is incorporated into the ice shelves, eventually grounding them to produce marine ice sheets on shallow continental shelves that thicken and advance onto land. This prevents north-flowing rivers in North America and Eurasia from reaching the sea, so sea level must drop rapidly, which causes further grounding of arctic ice shelves. The arctic then becomes a "White Hole" into which precipitation falls but cannot escape. This idea that Quaternary ice sheets rose up from the sea and advanced onto land hasn't caught on. It’s probably too topsy-turvy for most people. Perhaps MITH isn't the right acronym. In 1987, Boreas published "Deluge II and the Continent of Doom: Rising sea level and collapsing Antarctic ice." Deluge I was the Genesis flood. Deluge II will be gravitational collapse of the East Antarctic Ice Sheet, since it would submerge coastal lowlands to a depth of up to 65 meters. That would be a proper Deluge, especially if it was fast. My title was inspired by the movie, "Indiana Jones and the Temple of Doom." Arguing that the East Antarctic Ice Sheet could collapse rapidly is definitely topsy-turvy thinking. From 1986 to 1991, to prove I could be conventional, I collaborated in papers with George Denton, Wibjorn Karlen, Shamis Fastook, Mauri Pelto, Masayuki Nakagawa, John Scofield, Ian Whillans, Kees van der Veen, and others. 1992-2002 In 1994, Palaeo-3 published a topsy-turvy paper by my wife Bev and me called, "Transgressions: Re-thinking Beringian glaciation." A big problem was to explain why East Asians couldn't enter North America until after 12,000 years ago, when they supposedly had a land bridge 1000 kilometers wide, teeming with game, and had the West Wind at their backs for 80,000 years. Aboriginies had crossed a stormy shark-infested sea to Australia over 60,000 years ago. Bev and I argued that a lobe of the Arctic Ice Sheet shot through Bering Strait during the last glaciation, blocked the land bridge, and pushed down the shallow continental shelf of the Bering Sea, which didn't rebound above sea level until 12,000 years ago, long after the ice lobe was gone. I was then invited to the 1994 International Conference on Arctic Margins, held in the Russian port city of Magadan in the Sea of Okhotsk, to defend Misha Grosswald's (and my) ideas about former Siberian glaciation. By then, Misha and I were arguing for an ice sheet from Japan to Washington State on the North Pacific rim, as an extension of our Arctic Ice Sheet. I even co-chaired a workshop on this subject. Misha wasn't there, so I stood alone. The paper and the workshop deliberations were published in the Conference Proceedings in 1995. I riled enough people to spur field activities aimed at proving our topsy-turvy ideas were wrong. Julie Brigham-Grette’s work in Siberia is one example. In 1995, Misha Grosswald and I argued in the Journal of Glaciology that the Arctic Ice Sheet was "Paleoglaciology's grand unsolved problem." We borrowed our title from Hans Weertman's letter to Nature in 1976 stating that the marine West Antarctic Ice Sheet, also grounded below sea level on a continental shelf, was "Glaciology's grand unsolved problem." These problems are “unsolved” because the notion that ice sheets can ground in the sea and be “marine” seems topsy-turvy. Yet they existed then and one exists now. In 1996, I asked in Arctic and Alpine Research, "Can Ice Sheets Trigger Abrupt Climate Change?" The conventional view, one incorporated in CLIMAP, was that ice sheets were primarily passive components of Earth's climate machine. That's why CLIMAP chose to reconstruct global climates during the last glacial and interglacial maxima. Those were the maximum "cold" and "hot" reversible perturbations of a climate that was assumed to be fundamentally stable. I asked the topsy-turvy question, “What if Earth's climate is fundamentally unstable, always seeking but never finding some stable equilibrium?” Then we should investigate times of most rapid climate change because that is when the instability mechanisms are most dominant. Ice sheets are the components of Earth's climate machine that are the most unstable and the least permanent, so perhaps the fundamental instability mechanisms reside in them. When their changes are big enough and fast enough, perhaps they can trigger abrupt climate change. Since 1996, detailed climate records extracted from ice cores to bedrock at the summit of the Greenland Ice Sheet show rapid climate changes that are compatible with these ice-sheet instabilities. In 1998, Oxford University Press published my book, Ice Sheets. I wrote the book to rescue glaciologists from a trap set by Dick Peltier. He argued in 1992 in Science that climatology didn’t need glaciology. Given the shrinking areal extent of ice sheets during the last deglaciation, he could reconstruct the vertical extent of ice from the changing loads of ice and water on Earth's surface computed from his model of mantle rheology and the global sea-level curves. Just as glaciologists had gained access to the center ring under the Big Top in the circus of global climate change, Dick would banish us back to the Midway where we would resume our customary act biting the heads off chickens and snakes along with the rest of the sideshow geeks. I pointed to Dick's Achilles heel. His model, based on the most sluggish component of Earth's climate machine, couldn't produce abrupt climate change. Glaciologists could, once we got over the mental block of tying gravitational forcing to the basal shear stress that resists slow sheet flow with its sluggish response to any kind of forcing, and tied forcing to the “topsy-turvy” pulling stress that resists fast flow in ice streams, with an immediate response to even minor perturbations in forcing. NASA glaciologist Bob Thomas demonstrated this admirably in 2004 to account for the nearly doubled velocity of Jakobshavn Isbrae in only one year. The bad news: Oxford published Ice Sheets using my preliminary disc, which had many misprints. Bev and I sent Oxford the final corrected disc after Ice Sheets was in-press. A central theme in Ice Sheets was that all ice sheets have a relatively stable inner core surrounded by a relatively unstable outer periphery, where ice streams proliferate and manifest the instabilities. I proposed steady-state mechanisms of glacial erosion and deposition in the core that made a stronger first-order imprint on the landscape with each glaciation cycle, and transient mechanisms in the outer periphery that made a temporary second-order imprint that was either erased or reoriented during each advance and retreat of the unstable periphery. Allowing transient effects to override steady-state processes seems topsy-turvy. Yet, stadials and interstadials during a glaciation cycle correlate with unstable fluctuations of the periphery. Terminations occurred when these unstable transient mechanisms were able to penetrate the “stable” core and cause gravitational collapse of the whole ice sheet, something Peltier’s approach cannot simulate. Unstable mechanisms operated in ice streams and ice shelves that buttressed marine ice streams. Diagnostic applications for reconstructing former ice sheets were used for slow sheet flow in the stable core and fast stream flow in the unstable periphery. First-order glacial geology produced in the core can be interpreted as revealing where the bed had been frozen, thawed, and freezing or melting, with freezing and melting zones consisting of a mosaic of frozen and thawed patches. The thawed fraction is then used to compute former ice elevations, based on bed traction variations linked to basal thermal zones. First-order glacial geology in the unstable periphery locates former ice steams in glaciated valleys and straits. Their profiles are reconstructed based on what fraction of their basal ice was supported by basal water pressure, instead of by bedrock or till. Prognostic applications to assess the future behavior of present-day ice sheets calculate the thawed fraction under slow sheet flow and the floating fraction under fast stream flow, based the known bed topography, ice thickness, and ice surface slope along flowbands. Ellen Wilch and I did this for sheet flow in much of Antarctica, where these data were available. Our work was published in the Journal of Glaciology in 2000. Doug Reusch and I did it for stream flow in Byrd Glacier along one radio-echo flightline where the data were available. Antarctic Science published our work in 2003. 2002-2006 In 2003, Antarctic Science published the paper by Doug Reusch and me that determined the pulling power of Byrd Glacier by calculating the fraction of its basal ice overburden pressure that was supported by basal water pressure, instead of by bedrock. Byrd Glacier pulls more ice out of Antarctica than does any other ice stream. Of course ice streams pulling ice out of ice sheets is topsy-turvy to ice being pushed out. In 2003, the Journal of Geophysical Research published my paper on the "Geometrical force balance in glaciololgy." Referees were Bob Thomas and Hans Weertman. This was my “topsy-turvy” alternative to integrating the Navier-Stokes equations, updated from my 1992 “pulling power” paper in the Journal of Glaciology, after twelve years. That's progress. My graduate student in physics, Jim Kenneally, and I began publishing our series of papers in Antarctic Science showing how advancing top and bottom crevasses can form and intersect on floating ice shelves that thin by basal melting and creep, and release giant tabular icebergs when crevasses meet. This has been observed on the huge Filchner, Ronne, and Ross ice shelves of West Antarctica in recent years. We provided a mechanism. These papers harkened back to my first papers on ice-shelf disintegration, in 1982 by thinning from creep and melting, and in 1983 by fracture. Back then, there was little interest in calving because that was when ice left the glacier system. However, it entered the larger climate system, a topsy-turvy perspective that makes calving important. In 2004, Polar Meteorology and Glaciology published, “Greenland Ice Sheet and rising sea leveling a worst-case climate change scenario.” I used my pulling-power approach to model how surface meltwater reaching the bed through crevasses could make Greenland ice streams surge, as in the Jakobshavn Effect. Over a period of 300 years, enough ice would be calved from these ice streams to halt production of North Atlantic Deep Water and throw Europe into another Little Ice Age. That’s a topsy-turvy view showing how ice sheets can trigger rapid climate change, instead of merely responding passively to it. In 2005, NSF gave the University of Kansas $19 million over five years to establish a science and technology center called the Center for Remote Sensing of Ice Sheets (CReSIS), with the expectation of $20 million more over a second five years. The scientific goal of CReSIS is to link rising sea level with lowering ice sheets over Antarctica and Greenland, with special attention to Thwaites Glacier and Pine Island Glacier in Antarctica, and to Jakobshavn Isbrae in Greenland. These are the very ice streams I had pinpointed for field studies in 1981 and 1986, when that was topsy-turvy thinking. So there’s more progress. The University of Maine (UM) has a piece of the action. We get to model these ice streams and both ice sheets, using all the data coming in from field studies, from Earth-orbiting satellites, from aircraft equipped for remote sensing, and from unmanned remote-controlled surface and air "autonomous platforms" that will collect data along programmed gridlines on the Antarctic and Greenland ice sheets. The University of Kansas (KU) will develop the "autonomous platforms" and participate in all data acquisition. Data acquisition and modeling will also be done at The Ohio State University (OSU) and The Pennsylvania State University (PSU). In 2006, I will be teaching a two-week glaciology course in June at Elizabeth City State University (ECSU) in North Carolina. ECSU and Haskell Indian Nations University (HINU) in Kansas participate in the minority outreach component of CReSIS. ECSU trains Black students for careers in science and technology. I aim to convince one or two to come to UM and work with me toward doctorates in glaciology, so they can then participate in CReSIS and other glaciological research funded by NSF and NASA. That would be topsy-turvy compared to now. HINU can help prepare American Indians for similar careers. I am now finishing a monograph, Holistic Ice Sheet Modeling: A First-Order Approach, that I will use in my glaciology course at ECSU and then in my courses at UM. If it helps the students, I'll get it published as a textbook in glaciology. Also in 2006, I'll be doing fieldwork again in Antarctica by participating in Paul Mayewski's American ITASE (ITASE: International Trans-Antarctic Scientific Expeditions) tractor-train traverse from Taylor ice dome near the Dry Valleys to the South Pole. This traverse will include an important side traverse part way up and down an ice flowline from the Russian Vostok Station in central East Antarctica to Byrd Glacier, where I did field work in the 1978-1979 Antarctic summer season. The Russians have extracted a climate record 4 kilometers long in a corehole to subglacial Lake Vostok. Byrd Glacier drains ice from that whole region over which the climate record accumulated for a million years. That will provide the basis for a proposal to NSF to map the floor of Byrd Glacier using gridded radio-echo flightlines along its entire length, so Shamis Fastook and I can do a state-of-the-art computer simulation of its dynamics. After 2006, I plan to continue with the ITASE traverse from the South Pole through the east side of The Bottleneck between the East and West Antarctic Ice Sheets, and on to the WAIS drilling site on the West Antarctic ice divide where ice flow discharged by Thwaites Glacier begins. An earlier ITASE traverse passed through the west side of The Bottleneck. ITASE data along these traverses will allow Shamis Fastook and me to model collapse of the West Antarctic Ice Sheet into the Pine Island Bay polynya, primarily through Thwaites Glacier, and then to model East Antarctic ice surging into West Antarctica through The Bottleneck after the West Antarctic Ice Sheet is largely downdrawn or even gone completely. Then the West Antarctic ice Sheet can not only form the East Antarctic Ice Sheet, it can get rid of it by sucking out its heart, as I outlined in Ice Sheets (Figure 3.28, page 88) in a worst-case deglaciation scenario. How much more topsy-turvy can you get? Showing that collapse of the West Antarctic Ice Sheet triggers collapse of the much larger East Antarctic Ice Sheet would be topsy-turvy science of the highest order. To do this correctly, Shamis will need a solution for the full Navier-Stokes equations. But I can provide a first-order solution from my geometrical force balance. If we can pull this off, that will be real progress. Terry Hughes, April Fool’s Day, 2006 |