MUST SEE TV: ICE ICE MAYBE (NOT)
climateprogress.org
November 27, 2007
Original LinkDo you want the latest data -- some not yet published -- and the best post-IPCC scientific predictions for the stunning collapse of Arctic ice and unexpected shrinking of the Greenland (and Antarctic) ice sheets? Then you should definitely watch this C-SPAN video of yesterday’s American Meteorological Society seminar (see below for more information).
The seminar is by three of the world’s top cryosphere experts: Dr. Mark Serreze (NOAA), Scott Luthcke (NASA), and Dr. Konrad Steffen (CIRES) -- full bios and program summary available (below). I will post their presentations when AMS puts them online.
I have spent a great deal of time studying the ice and sea level rise issue and still found the presentations informative and startling. It is very safe to say the Arctic Sea will be essentially ice free by 2030, and I’d personally bet on 2020 -- any takers?
The most interesting presentation to me was the last one, by Konrad Steffen, who made a convincing case that the IPCC is “underestimating the rate of sea level rise” this century significantly. He expects one meter or more by 2100. The modelers are busy at work trying to account for ice dynamics in ice sheet collapse -- but it may take 4 or 5 years for them to do that. When they are finished, sea level rise estimates for this century are likely to double or triple.
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Watch The Presentations On C-SPAN------------
AMS SEMINAR:
ARCTIC SEA ICE MELT AND SHRINKING POLAR ICE SHEETS
ARE OBSERVED CHANGES EXCEEDING EXPECTATIONS?
Monday, November 26, 2007
Dirksen Senate Office Building, Room 106 Washington DC
Original LinkIs the Arctic sea ice cover melting faster than expected? If so, what are the contributing factors and why was the rate of melting unanticipated? How much sea ice cover has been lost in terms of extent and volume? What are the implications of both the loss of sea ice and the rate of loss? Is the Greenland ice sheet losing its mass faster than anticipated? If so, what are the contributing factors and why was the rate of loss unanticipated? What are the implications of continued accelerated ice loss from the Greenland ice sheet with respect to Sea Level Rise? Is the Antarctic Ice Sheet getting bigger or smaller and by how much and how fast? Are there parts of the Antarctic ice sheet that are gaining mass and parts that are losing mass? If so, what are the contributing causes? What are the implications of continued ice mass loss in Antarctica, especially the decay of ice shelves?
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Moderator:
Dr. Anthony Socci, Senior Science Fellow, American Meteorological Society
Speakers:
Dr. Mark Serreze, Senior Research Scientist, NOAA National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO
Scott B. Luthcke, Geophysicist, NASA Goddard Space Flight Center’s Planetary Geodynamics Laboratory, Greenbelt, MD
Dr. Konrad Steffen, Professor of Climatology and Remote Sensing and Director of the Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO
Complete Biographies............
PROGRAM SUMMARY
RATES OF CHANGE IN ARCTIC SEA ICE COVER: CAUSATION, EXTENT AND IMPLICATIONS
* Since the advent of routine monitoring via satellite in 1979, the area of the Arctic Ocean covered with sea ice, known as ice extent, has declined in all months, most strongly in September. The rate of ice loss appears to have accelerated in recent years. Sea ice extent for September 2007 was the lowest ever recorded, beating the old record set in September 2005 by 23%, an area the size of Texas and California combined.
* Essentially all state-of-the-art global climate models indicate that sea ice extent should be declining over the period of observations, pointing strongly to a role of increased greenhouse gas concentrations. However, the observed rate of decline in September exceeds that from nearly all models. While natural climate variability explains part of the observed rapid ice loss, it appears that the models, as a group, are underestimating the sensitivity of the ice cover to the effects of greenhouse warming.
* There is strong evidence that reductions in sea ice extent have been accompanied by substantial thinning. There is growing recognition that once the ice thins sufficiently, it will become sensitive to a "kick" from natural climate variations that, through feedback mechanisms such as ocean warming in ice free regions due to solar radiation, result in rapid loss of the remaining summer ice cover.
* Transition to an ice-free Arctic Ocean in summer could occur as early as 2030. While climate simulations suggest that ice loss may have impacts on weather patterns well beyond the Arctic, little is known at this time. While ice loss will have adverse ramifications for Arctic ecosystems and the peoples of the Arctic, given the current trajectory, the region will also become accessible to shipping and resource exploitation. The summer of 2007 saw the fabled Northwest passage open for the first time since regular monitoring began in 1972.
RECENT OBSERVATIONS ON CHANGES IN POLAR LAND ICE MASS
Mass changes of the Earth's ice sheets and glacier systems are of considerable importance because of their sensitivity to climate change and their contribution to rising sea level. Recent changes in the cryosphere highlight the importance of methods for directly observing the complex spatial and temporal variation of land ice mass flux. Since its launch in March of 2002, the NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission has been acquiring ultra-precise inter-satellite K-band range and range-rate (KBRR) measurements enabling a direct mapping of static and time-variable gravity. These data provide new opportunities to observe and understand ice mass changes at unprecedented temporal and spatial resolutions. Through the detailed reduction of these GRACE KBRR data, we have computed multi-year time series of surface mass flux for Greenland and Antarctica coastal and interior ice sheet sub-drainage systems as well as the Alaskan glacier systems. These mass flux solutions provide important observations of the seasonal and inter-annual evolution of the Earth's land ice as well as overall trends.
The gravity observations show the Greenland ice sheet is losing significant mass at the low elevation coastal regions that is not compensated for by gains in the high elevation interior resulting in an overall rate of loss of 154±10 Gt/yr. In addition strong inter-annual variations are observed such as the large mass loss of 2005 resulting from higher surface temperatures and a longer melt season. The gravity observations show the Antarctic ice sheet is losing mass at the rate of 105±30 Gt/yr with the loss concentrated from the western Antarctic ice sheet and in particular at the tip of the peninsula. The high elevation regions of the Antarctic ice sheet are showing no significant rate of change in mass. The Alaskan mountain glaciers are observed to be losing mass at a rate of 98±8 Gt/yr with the largest losses observed in the Yakutat Icefields and Glacier Bay regions. The combination of GRACE high-resolution mass flux observations together with the surface elevation change and surface melt observations is beginning to reveal a detailed understanding of the Earth's high latitude land ice evolution.
GREENLAND ICE SHEET: DYNAMIC RESPONSE TO RECENT CLIMATE WARMING
Recent rapid changes in marginal regions of the Greenland ice sheet show mainly acceleration and thinning, with some glacier velocities increasing more than twofold. Recent data show a high correlation between periods of heavy surface melting and increase in glacier velocity. A possible cause is rapid meltwater drainage to the glacier bed, where it enhances basal sliding.
An increase in meltwater production in a warmer climate could have major consequences on ice-flow rate and mass loss. Melt extent on the ice sheet for 2007 was the largest ever recorded since the beginning of satellite measurements in 1979, beating the old record set in 2005 by 10%, an area.
The Greenland Ice Sheet is losing mass, and that this has most likely been accelerating since the mid 1990s. Although Greenland has been thickening at high elevations, because of the predicted increase in snowfall, this gain is more than offset by an accelerating mass loss, with a large component from rapidly-thinning and accelerating outlet glaciers. The mass balance decreased from near balance in the early 1990's to minus 100 Giga tons (Gt) or even less than 200 Giga tons of ice for the most recent observations in 2006.
The likely sensitive regions for future rapid changes in ice volume are those outlet glaciers in Greenland like the Jakobshavn Isbrae, with an over-deepened channel reaching far inland. Inclusion of these processes in models will likely demonstrate that the Intergovernmental Panel on Climate Change's 4th Assessment (2007) Report underestimated sea-level projections for the end of the 21st Century.
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