Comments on: Latest Greenland ice sheet reflectivity http://www.meltfactor.org/blog/?p=514 the ice and climate web log of Jason E. Box, Ph.D. Fri, 17 May 2013 10:54:25 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Dramatic Lessons from the Arctic Big Melt of 2012 http://www.meltfactor.org/blog/?p=514&cpage=1#comment-5862 Dramatic Lessons from the Arctic Big Melt of 2012 Wed, 15 Aug 2012 23:10:19 +0000 http://www.meltfactor.org/blog/?p=514#comment-5862 [...] Greenland: Those circumstances as well as rising global temperatures will increase the rate of melting of the Greenland ice sheet, which is already accelerating. Total ice sheet mass loss in 2011 was 70 per cent larger than the 2003-2009 average annual loss rate of 250 gigatons per year. And now, today, we have news of a record melt in 2012 with another month of the melt season to go. And now the tipping point for Greenland’s ice sheet (eventual sea level rise of 7 metres) has been revised down from around 3ºC to just 1.6ºC (uncertainty range of 0.8-3.2ºC). At the current temperature rise of 0.8ºC we may have already reached Greenland’s tipping point, and with temperature rises in the pipeline (global emissions still rising, no reasonable agreement to reduce them), we are very likely to hit 1.6ºC in two, or three, decades. The albedo (reflective capacity of a surface, measured as a percentage) of the Greenland ice sheet, particularly the high-elevation areas where snow typically accumulates year-round, have reached a record low since satellite records began in 2000. This indicates that the ice sheet is absorbing more energy than normal. Albedo has dropped significantly in 2012 (black line). There are more charts here. [...] [...] Greenland: Those circumstances as well as rising global temperatures will increase the rate of melting of the Greenland ice sheet, which is already accelerating. Total ice sheet mass loss in 2011 was 70 per cent larger than the 2003-2009 average annual loss rate of 250 gigatons per year. And now, today, we have news of a record melt in 2012 with another month of the melt season to go. And now the tipping point for Greenland’s ice sheet (eventual sea level rise of 7 metres) has been revised down from around 3ºC to just 1.6ºC (uncertainty range of 0.8-3.2ºC). At the current temperature rise of 0.8ºC we may have already reached Greenland’s tipping point, and with temperature rises in the pipeline (global emissions still rising, no reasonable agreement to reduce them), we are very likely to hit 1.6ºC in two, or three, decades. The albedo (reflective capacity of a surface, measured as a percentage) of the Greenland ice sheet, particularly the high-elevation areas where snow typically accumulates year-round, have reached a record low since satellite records began in 2000. This indicates that the ice sheet is absorbing more energy than normal. Albedo has dropped significantly in 2012 (black line). There are more charts here. [...]

]]> By: Jason Box http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3734 Jason Box Thu, 26 Jul 2012 14:06:00 +0000 http://www.meltfactor.org/blog/?p=514#comment-3734 The alberto of lower altitudes is so much higher compared to other years because that surface is already as low as it should get. The extreme lowest elevations, the albedo increases again because the impurities begin concentrating near the surface. An albedo increase at the lowest elevations, I suspect, is due to the 'white ice' area moving to higher elevations. This is very interesting, but of little consequence to the increasingly negative mass balance of the ice sheet. Jason The alberto of lower altitudes is so much higher compared to other years because that surface is already as low as it should get. The extreme lowest elevations, the albedo increases again because the impurities begin concentrating near the surface. An albedo increase at the lowest elevations, I suspect, is due to the ‘white ice’ area moving to higher elevations. This is very interesting, but of little consequence to the increasingly negative mass balance of the ice sheet.

Jason

]]> By: Greenland’s extraordinary summer: melting records and ice island setting sail http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3695 Greenland’s extraordinary summer: melting records and ice island setting sail Thu, 26 Jul 2012 11:11:31 +0000 http://www.meltfactor.org/blog/?p=514#comment-3695 [...] ice sheet at 3,200 meters, initiating surface melt over the whole vast sheet, ice sheet albedo has plummeted, and the Jakobshavn Isbrae’s calving front has retreated into the ice [...] [...] ice sheet at 3,200 meters, initiating surface melt over the whole vast sheet, ice sheet albedo has plummeted, and the Jakobshavn Isbrae’s calving front has retreated into the ice [...]

]]> By: Ghiacci artici: minimo assoluto di estensione! - Pagina 10 http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3540 Ghiacci artici: minimo assoluto di estensione! - Pagina 10 Wed, 25 Jul 2012 18:19:38 +0000 http://www.meltfactor.org/blog/?p=514#comment-3540 [...] [...] [...] [...]

]]> By: 97% of Greenland has experienced surface melting this month ,record temps expected next week . « toolwielder http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3503 97% of Greenland has experienced surface melting this month ,record temps expected next week . « toolwielder Wed, 25 Jul 2012 15:05:15 +0000 http://www.meltfactor.org/blog/?p=514#comment-3503 [...] Figure 2. The albedo (reflectivity) of the Greenland Ice Sheet at its highest elevations (2,500 – 3,200 meters, or 8,200 – 10,500 feet) has steadily decreased in recent years as the ice has darkened due to increased melting and dark soot being deposited on the ice from air pollution. This July, the high elevations of Greenland were the darkest on record, which helped contribute to the record warm temperatures observed at the Greenland Summit. Image credit: Dr. Jason Box, Ohio State University. [...] [...] Figure 2. The albedo (reflectivity) of the Greenland Ice Sheet at its highest elevations (2,500 – 3,200 meters, or 8,200 – 10,500 feet) has steadily decreased in recent years as the ice has darkened due to increased melting and dark soot being deposited on the ice from air pollution. This July, the high elevations of Greenland were the darkest on record, which helped contribute to the record warm temperatures observed at the Greenland Summit. Image credit: Dr. Jason Box, Ohio State University. [...]

]]> By: Darth Vader http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3261 Darth Vader Mon, 23 Jul 2012 13:26:11 +0000 http://www.meltfactor.org/blog/?p=514#comment-3261 The alberto of higher altitudes seems to be very low this year, but why is it that the alberto of lower altitudes is so much higher compared to other years? The alberto of higher altitudes seems to be very low this year, but why is it that the alberto of lower altitudes is so much higher compared to other years?

]]> By: Rob Dekker http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3259 Rob Dekker Mon, 23 Jul 2012 10:20:24 +0000 http://www.meltfactor.org/blog/?p=514#comment-3259 Dr.Box, I'm sorry. I was mistaken about NOA. Indeed the summer NOA index (JJA) seems to be at record negative since 2007. http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table I'll read your paper in more detail before drawing any conclusions regarding the origin of the temperature increases around Greenland. Still, could you please comment on the 4 polynomial orders of feedback, especially the snow cover anomaly over the Northern Hemisphere, and what this may mean for Greenland's melt rate ? Dr.Box, I’m sorry. I was mistaken about NOA. Indeed the summer NOA index (JJA) seems to be at record negative since 2007.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.nao.monthly.b5001.current.ascii.table
I’ll read your paper in more detail before drawing any conclusions regarding the origin of the temperature increases around Greenland.
Still, could you please comment on the 4 polynomial orders of feedback, especially the snow cover anomaly over the Northern Hemisphere, and what this may mean for Greenland’s melt rate ?

]]> By: Jason Box http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3183 Jason Box Sat, 21 Jul 2012 12:13:19 +0000 http://www.meltfactor.org/blog/?p=514#comment-3183 Rob, I like this kind of calculation, do something similar in the attached, find the extra energy erodes 14 cm of the 'cold content' of the upper snow layers across the accumulation area... Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., and Steffen, K.: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere Discuss., 6, 593-634, doi:10.5194/tcd-6-593-2012, 2012. <a href="http://bprc.osu.edu/~jbox/temp/Box%20et%20al.%202012%20-%20TCD%20-%20resubmitted%20after%20review%20round%202.pdf" rel="nofollow">DOWNLOAD LATEST, ACCEPTED VERSION</a> Rob, I like this kind of calculation, do something similar in the attached, find the extra energy erodes 14 cm of the ‘cold content’ of the upper snow layers across the accumulation area… Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., and Steffen, K.: Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers, The Cryosphere Discuss., 6, 593-634, doi:10.5194/tcd-6-593-2012, 2012. DOWNLOAD LATEST, ACCEPTED VERSION

]]> By: Rob Dekker http://www.meltfactor.org/blog/?p=514&cpage=1#comment-3176 Rob Dekker Sat, 21 Jul 2012 08:08:50 +0000 http://www.meltfactor.org/blog/?p=514#comment-3176 Dr. Box, thank you for showing the disturbing change in albedo at Greenland this year. Quick question with possibly significant consequences : We know that Greenland receives some 250 - 300 W/m^2 insolation 'on the ice' during June/July. With a change in albedo of 3 % to (as your recent numbers show) to 6 %, how much ice will melt over the entire ice sheet due to this change in albedo alone ? If we do the simple physics calculations of increased solar absorption of 3-6% albedo change, we get to a ice loss anomaly of some 7 - 14 cm or, over the entire 1.7 million km^2 ice sheet, an additional loss of 120 - 240 Gton per month (that the surface temps remain close to freezing on Greenland) due to this albedo anomaly alone. Please tell me that these calculations are not right, because if they are, we should be very concerned... Dr. Box, thank you for showing the disturbing change in albedo at Greenland this year.
Quick question with possibly significant consequences :
We know that Greenland receives some 250 – 300 W/m^2 insolation ‘on the ice’ during June/July.
With a change in albedo of 3 % to (as your recent numbers show) to 6 %, how much ice will melt over the entire ice sheet due to this change in albedo alone ?

If we do the simple physics calculations of increased solar absorption of 3-6% albedo change, we get to a ice loss anomaly of some 7 – 14 cm or, over the entire 1.7 million km^2 ice sheet, an additional loss of 120 – 240 Gton per month (that the surface temps remain close to freezing on Greenland) due to this albedo anomaly alone.

Please tell me that these calculations are not right, because if they are, we should be very concerned…

]]> By: Greenland melt record likely http://www.meltfactor.org/blog/?p=514&cpage=1#comment-2668 Greenland melt record likely Thu, 28 Jun 2012 00:17:55 +0000 http://www.meltfactor.org/blog/?p=514#comment-2668 [...] the latest “noodle plot”2 (regularly updated here) for the ice sheet between elevations of 2,000 and 2,500 metres. 2012 (the black line) is well down [...] [...] the latest “noodle plot”2 (regularly updated here) for the ice sheet between elevations of 2,000 and 2,500 metres. 2012 (the black line) is well down [...]

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