Possible Sea Level Rise of 1-3 meters (or more) within the next 50 years
Emission reduction could slow the process of melting
A record amount of Arctic Sea Ice melted away during June 2012 +++ New research highlights Himalayan glaciers melting more rapidly +++ Antarctica is getting warmer - This is a surprise because conventional wisdom has tended to think of Antarctica being getting progressively colder.
Update
In a recent video Richard Alley explains how abrupt SLR can happen from Ice Sheet Disintegration.
Just 2.2 °C doesn’t sound like much (although it looks to be a new record for July), until one realises that we are talking Summit Camp here. At an altitude of 3200 metres. In the middle of the Greenland ice sheet. Nothing but ice."
The potential for sustained rapid ice loss and catastrophic sea-level rise in the near future is confirmed by our discovery of sea-level instability at the close of the last interglacial.
The Eemian was some 2°C warmer than current global temperatures — we will exceed that over most of the second half of this century on our current emissions path"
Joe Romm: "In other words, the Nature study says that during the last interglacial (the Eemian) evidence now suggests sea levels rose 20 inches per decade for five straight decades — a roughly 8-foot rise in a half century.
The paleoclimate record also shows that 560 ppm would be enough to melt all the ice in the Arctic, and later the Antarctic. Rohling said that once the Antarctic melts, sea levels would rise by 60 to 70 meters. “If governments keep going the way they are going,” Hansen added, “the planet will reach an ice-free state.” Scientific American
“Just the melting of all the floating ice in the arctic ocean, will add as much heat to the earth, as all the Co-2 we put in the atmosphere to date.” Prof. James Lovelock
Estimating the Global Radiative Impact of the Sea-Ice-Albedo Feedback in the Arctic a more realistic ice-free-summer scenario (no ice for one month, decreased ice at all other times of the year) results in a forcing of about 0.3 W m−2, similar to present-day anthropogenic forcing caused by halocarbons. BBC Interview with James Lovelock
Image "The ice free state" Source | World Map: The point of this image is to show the impact from an ice free planet. Because that is where we heading on current emission path. The water distribution is not accurate since it is assumed that all melted ice would yield 80 meters of SLR. But this number does not include thermal expansion of the ocean. With current emission we will get to something similar. Because water-mass is not distributed equally through the planet, but based on gravitation. The current rate humans put Co2 into the atmosphere is 10,000 times faster than the natural processes.
For that matter and potential singular positive feedbacks the rate of Sea Level Rise (SLR) can be assumed to rise with a similar factor. And for that matter there is no equivalent in the earth recorded history. Related Sea Level vs Temperature | Coefficients of Thermal Expansion for Selected Materials
And a study from 2009 found: Using contiguous reef crests -- the part of the reef closest to the surface of the water -- as benchmarks, the researchers pinpointed a dramatic jump in sea levels that occurred 121,000 years ago. "We are looking at a three-metre rise in 50 years," Banchon said. "This is the first evidence that we have for rapid change in sea level during that time." Only collapsing ice sheets could account for such an abrupt increase, he added.
The last interglacial period, when sea levels peaked six metres higher than current levels, was warmer than the world is today. But as manmade climate change kicks in, scientists worry that rising temperatures could create a similar environment, triggering a runaway disintegration of the continent-sized ice blocks that are already showing signs of distress. Source
Watch the Video below, to get an idea of Greenland ice melt:
Neven: "Levels in the Akuliarusiarsuup Kuua river, also knows as the Watson river, have reached such heights that they have smashed the two bridges connecting the north and south of Kangerlussuaq, a small settlement in southwestern Greenland. 3.5 million liters of water pressed through the narrow river every second. It’s almost a doubling of previous records. It’s no wonder that a 20 ton wheel loader was torn away from the bridge in Kangerlussuaq like a toy."
Parts of the planet warmed already comparable to the past in earth history, when sea level rise went quickly.
These findings and current ice melt observation trends suggest that we are already observing a situation where we might have to deal with 1-3 meters of sea level rise within the next 50 years.
Artic Sea ice
Andrew Freedman explains: "Sea ice extent is currently running just below the level seen at the same time in 2007, the year that set the record for the lowest sea ice minimum in the satellite era."Greenland
Neven explains the recent ice melt in Greenland: "In Greenland, it has been very hot over the inland ice in comparison to normal conditions. On July 11th at 15 UTC the recorded temperature at the Summit Camp weather station, which is located at the ice cap’s highest altitude (3200 metres), was 2.2 degrees Celsius. That is quite high for this height, particularly in light of the fact that ice has a relatively high albedo.Just 2.2 °C doesn’t sound like much (although it looks to be a new record for July), until one realises that we are talking Summit Camp here. At an altitude of 3200 metres. In the middle of the Greenland ice sheet. Nothing but ice."
What the past teaches us
Back in 2009, CP wrote about a study on rapid sea level rise: "These observations are in agreement with a sudden, catastrophic increase of more than 5 centimetres Sea Level Rise, per year over a 50-year stretch."The potential for sustained rapid ice loss and catastrophic sea-level rise in the near future is confirmed by our discovery of sea-level instability at the close of the last interglacial.
The Eemian was some 2°C warmer than current global temperatures — we will exceed that over most of the second half of this century on our current emissions path"
Joe Romm: "In other words, the Nature study says that during the last interglacial (the Eemian) evidence now suggests sea levels rose 20 inches per decade for five straight decades — a roughly 8-foot rise in a half century.
Sea Level Rise (SLR)
If the number reaches 560 ppm, a doubling of preindustrial values, sea level globally could rise 25 meters, according to Eelco Rohling, professor of ocean and climate change at University of Southampton in the U.K., who presented data at the AGU meeting with Hansen. Many large cities worldwide lie at that elevation or lower. The two scientists agreed that if nations continue to emit CO2 at current rates, the world could reach 560 ppm by 2100.The paleoclimate record also shows that 560 ppm would be enough to melt all the ice in the Arctic, and later the Antarctic. Rohling said that once the Antarctic melts, sea levels would rise by 60 to 70 meters. “If governments keep going the way they are going,” Hansen added, “the planet will reach an ice-free state.” Scientific American
Non Linear Problems from Albedo Flip Effect
The amplifying feedback mechanism of polar ice melt is the so-called albedo-flip effect, where loss of reflection by melted ice is compounded by infrared absorption by open water, a process currently taking place in the Arctic Sea, as reported by Hansen et al.: “… amplifying feedbacks make ice sheet disintegration necessarily highly non-linear. In a non-linear problem, the most relevant number for projecting sea level rise is the doubling time for the rate of mass loss. Hansen (2007) suggested that a 10-year doubling time was plausible, pointing out that such a doubling time from a base of 1 mm per year ice sheet contribution to sea level in the decade 2005-2015 would lead to a cumulative 5 m sea level rise by 2095.” http://www.countercurrents.org/glikson050411.pdf“Just the melting of all the floating ice in the arctic ocean, will add as much heat to the earth, as all the Co-2 we put in the atmosphere to date.” Prof. James Lovelock
Estimating the Global Radiative Impact of the Sea-Ice-Albedo Feedback in the Arctic a more realistic ice-free-summer scenario (no ice for one month, decreased ice at all other times of the year) results in a forcing of about 0.3 W m−2, similar to present-day anthropogenic forcing caused by halocarbons. BBC Interview with James Lovelock
Impact from 100 meter Sea Level Rise
For that matter and potential singular positive feedbacks the rate of Sea Level Rise (SLR) can be assumed to rise with a similar factor. And for that matter there is no equivalent in the earth recorded history. Related Sea Level vs Temperature | Coefficients of Thermal Expansion for Selected Materials
And a study from 2009 found: Using contiguous reef crests -- the part of the reef closest to the surface of the water -- as benchmarks, the researchers pinpointed a dramatic jump in sea levels that occurred 121,000 years ago. "We are looking at a three-metre rise in 50 years," Banchon said. "This is the first evidence that we have for rapid change in sea level during that time." Only collapsing ice sheets could account for such an abrupt increase, he added.
The last interglacial period, when sea levels peaked six metres higher than current levels, was warmer than the world is today. But as manmade climate change kicks in, scientists worry that rising temperatures could create a similar environment, triggering a runaway disintegration of the continent-sized ice blocks that are already showing signs of distress. Source
Watch the Video below, to get an idea of Greenland ice melt:
Neven: "Levels in the Akuliarusiarsuup Kuua river, also knows as the Watson river, have reached such heights that they have smashed the two bridges connecting the north and south of Kangerlussuaq, a small settlement in southwestern Greenland. 3.5 million liters of water pressed through the narrow river every second. It’s almost a doubling of previous records. It’s no wonder that a 20 ton wheel loader was torn away from the bridge in Kangerlussuaq like a toy."
Conclusion
Greenland, Antarctica and Glaciers are melting faster than previously thought.Parts of the planet warmed already comparable to the past in earth history, when sea level rise went quickly.
These findings and current ice melt observation trends suggest that we are already observing a situation where we might have to deal with 1-3 meters of sea level rise within the next 50 years.
Comments (3)
Martin Vermeer
http://publishing.cdlib.org/ucpressebooks/view?docId=kt167nb66r&chunk.id=d3_4_ch03&toc.id=ch03&brand=eschol
See how much sea-level rise you can produce from that (and yes, the heat has to be transported from the surface down, and that takes time)
prokaryotes
Martin Vermeer
Even Hansen's 5 m by 2100 is a stretch. It requires an exponential growth mechanism, like melt feeding back and begetting more and more melt. 'Albedo flip' doesn't do that, and I'm not sure what does. The only place where a real collapse like that is thinkable is West Antarctica, which could give 3 m in a short time.