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Lennartvdl
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Nice guest blog in the Guardian, Neven: http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/jul/29/2015-arctic-melting-season-wont-break-records-but-could-wipe-the-recovery?CMP=twt_environment*gdneco [Thanks, Lennart. I was waiting for this to get published. Still can't log in on my own blog, which is why I answer like this; N.]
o-oh...
Toggle Commented Jul 10, 2015 on ASI 2015 update 4: massive heat at Arctic Sea Ice
Can you tell what kind of alien?
Toggle Commented Jul 10, 2015 on ASI 2015 update 4: massive heat at Arctic Sea Ice
Colorado Bob, thanks for the link to the Alley-lecture. I reposted it on the ASIF.
"157 million people living at an average of 10m abovw sea level" If I remember correctly worldwide about 600 million to one billion live at 10m or less above sea level.
Toggle Commented May 15, 2015 on Bill McKibben nails it at Arctic Sea Ice
"It’s as if the tobacco companies were applying for permission to put cigarette machines in cancer wards. And the White House gave Shell the license." There's an important difference with smoking though: smoking can be done without endangering everyone else's health; burning oil and emitting CO2 can't be done without endangering the health of everyone else's home planet.
Toggle Commented May 15, 2015 on Bill McKibben nails it at Arctic Sea Ice
Nice report, Neven, thanks. On the links, this one to Torge Martin is not right: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-2018.pdf On the regional model by Maslowski and his group: did they say anything (new) on their 2016 +/- 3yrs ice-free projection/extrapolation?
Toggle Commented Apr 27, 2015 on EGU 2015, my impressions at Arctic Sea Ice
Susan, This may be the best place at the forum to start: http://forum.arctic-sea-ice.net/index.php/topic,393.0.html But it may take some time to find the info you're looking for, if it's there.
Toggle Commented Apr 3, 2015 on The Ns are calling the maximum at Arctic Sea Ice
It may be unlikely the max will be passed, but we've been surprised before. Neven, you write: "Quite a few storms have been funnelled into the Arctic via this route this winter, but this is a really big one, potentially bombing out at 950 hPa. It's difficult to tell what its influence will be on extent numbers at this final stage of the melting season." This "melting season" should be "freezing season", right?
Toggle Commented Mar 6, 2015 on Mad max? at Arctic Sea Ice
"What kind of chicken did we have in the oven?" That indeed seems to be the question. How frozen was it? How warm will the oven stay for how long, this year? Will the Arctic suprise us yet again?
Toggle Commented Jun 30, 2014 on ASI 2014 update 4: high times at Arctic Sea Ice
The NASA-post being picked-up: http://www.livescience.com/46264-greenland-glacier-loses-ice-photo.html
So far this year it seems to have been on average about 7 degrees C warmer than normal in the Arctic: http://ocean.dmi.dk/arctic/meant80n.uk.php Ice extent is at about the record minimum for this time of the year. And spring is in the air. At least here in Holland it is, where so far this winter we've had no full day below zero degrees C, for the first time ever. Average Holland temperature this winter (extended fall) has been second highest so far (only 2007 had a higher average). Let's see how fast the Northern hemisphere snow cover will melt this spring.
Arctic Report Card 2013 press conference at AGU Fall Meeting: http://www.youtube.com/watch?v=dZZsTgl-jHQ
SH, Nicely put. The strength of positive and negative feedbacks will determine the outcome, together with the GHG-forcing. And it seems we all do not know enough about how the ice caps will respond to this kind of forcing. GIS also seems to have two glacier fjords which extend deep into the interior of the ice cap, at Jakobshavn and Petermann glaciers. So although WAIS seems more unstable than GIS, this may be a pretty vulnerable ice sheet as well.
Toggle Commented Oct 3, 2013 on Pinpointing the minimum at Arctic Sea Ice
"Even more than doubling the current average melt rate to 400KM3/year we are still looking at a minimum of 700 years for the cap to melt out." You mean 7000 years, I suppose. Then again, over the past three years GIS lost about 400 km3/yr on average. Let's say this will continue until 2020. And then could this double in another 20 years to 800 km3/yr from 2020-2040? And then again to 1600 km3/yr from 2040-2060, and again to 3200 km3/yr from 2060-2080? Then the rate would be about 9 mm/yr of SLR contribution from GIS. If that rate could be sustained, with positive and negative feedbacks about in balance, then it would take about 700 years for near melt-out of GIS. I don't know if this is possible. And the risks for Antarctica seem higher. But scientists like Jim Hansen do suspect such accelerations could be possible under BAU. So I think it's too early to completely dismiss such scenarios.
Toggle Commented Oct 2, 2013 on Pinpointing the minimum at Arctic Sea Ice
Peter, We're all wondering the same. Part of the scientists seems to think it will take at least a thousand years. Another part seems to fear it may take as little as three or four centuries, if we continue with BAU.
Toggle Commented Oct 1, 2013 on Pinpointing the minimum at Arctic Sea Ice
Was it 40 cm of ice, or snow? Or a combination?
The Colbert Report reported on 'the lake at the North Pole': http://www.colbertnation.com/the-colbert-report-videos/428206/july-30-2013/smokin--pole---the-quest-for-arctic-riches--north-pole-lake
Look at figures 3, 4 and 5 in Bamber et al 2013, as linked above earlier: http://www.the-cryosphere.net/7/499/2013/tc-7-499-2013.pdf On pp.506-507 they say, as also cited above: “In the Jakobshavn catchment, there is a dendritic channel system extending for about 325 km from the current grounding line into the interior almost as far as the ice divide. It seems likely that this is a palaeo-fluvial feature that predates ice cover in Greenland and may be important for subglacial water routing… The width of the trough is 3–4 km and the region of fastest flow coincides fairly well with the location of the deepest ice. The trough is 1366m below sea level at its deepest point compared to a maximum depth over the entire region of 556m below sea level in the older dataset. The main trough of Jakobshavn Isbrae is not continuous in the new dataset, disappearing around 100 km and reappearing at about 140 km. This does not imply that the trough is discontinuous, but only that there are insufficient data to confirm the trough’s presence or otherwise in this region.” So it seems there may well be a connection below sea level into the interior bottom of the ice sheet. Looking at their figure 3a this may also be the case from Petermann Glacier into the interior.
From Bamber et al 2013 (linked above), pp.506-507: “In the Jakobshavn catchment, there is a dendritic channel system extending for about 325 km from the current grounding line into the interior almost as far as the ice divide. It seems likely that this is a palaeo-fluvial feature that predates ice cover in Greenland and may be important for subglacial water routing… The width of the trough 3–4 km and the region of fastest flow coincides fairly well with the location of the deepest ice. The trough is 1366m below sea level at its deepest point compared to a maximum depth over the entire region of 556m below sea level in the older dataset. The main trough of Jakobshavn Isbrae is not continuous in the new dataset, disappearing around 100 km and reappearing at about 140 km. This does not imply that the trough is discontinuous, but only that there are insufficient data to confirm the trough’s presence or otherwise in this region.” So maybe warming ocean water could in time eats it way into the interior bottom of the ice sheet?
Kevin, Bamber et al 2001 has been recently updated by Bamber et al 2013: http://www.the-cryosphere.net/7/499/2013/tc-7-499-2013.pdf It's not clear to me if they think the Jakobshavn glacier extends all the way inland below sea level or not, but it seems it might.
More fragmented ice than ever all over the Artic, partly because of the cyclone: http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic.2013169.terra.4km Thru the mostly clear sky and albedo flip warming and melting will now speed up. It will be interesting to see how fast.
Toggle Commented Jun 19, 2013 on On persistent cyclones at Arctic Sea Ice
Neven, I think many of us have moments like that. Someone like Paul Gilding has had them. He now says: http://paulgilding.com/the-great-disruption "The coming decades will see loss, suffering, and conflict as our planetary overdraft is paid; however, they will also bring out the best humanity can offer: compassion, innovation, resilience, and adaptability... The crisis represents a rare chance to replace our addiction to growth with an ethic of sustainability, and it’s already happening. It’s also an unmatched business opportunity: Old industries will collapse while new companies will literally reshape our economy. In the aftermath of the Great Disruption, we will measure “growth” in a new way. It will mean not quantity of stuff but quality and happiness of life. Yes, there is life after shopping." What doesn't kill us, can hopefully make us stronger :)
The complete Nature-article on MWP 1A is here and explains the uncertainty margins: http://sciences.blogs.liberation.fr/files/deschamps12nature-1.pdf An earlier one gave a range of 290-500 years for a pulse of 14-24 meters: http://oceanography.dal.ca/publications/files/Kienast_et_al._2003_Geol.pdf It seems the uncertainty is gradually narrowing down, even if there's still quite some debate on the sources/causes.
Toggle Commented Oct 4, 2012 on PIOMAS October 2012 (minimum) at Arctic Sea Ice
Andrew, Nice overview, thanks. On Meltwater Pulse 1A there seems to exist some debate as to the probable sources and speed, with most estimates ranging from 3-5 m/century, but maybe even up to 10 m/century, if this Wikipedia entry is correct: http://en.wikipedia.org/wiki/Meltwater_pulse_1A Maybe that's where your 10 m/century came from? Also see for example: http://www.nature.com/nature/journal/v483/n7391/full/483549a.html The dating here seems to be extremely exact (duration of the pulse of 340 years). Don't know how reliable that is.
Toggle Commented Oct 4, 2012 on PIOMAS October 2012 (minimum) at Arctic Sea Ice