Comments on: Greenland Melting is Accelerating http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html Chronicling and Commenting on Human Progress Wed, 10 Mar 2010 09:16:39 +0000 http://wordpress.org/?v=2.2 By: Anthonares » Blog Archive » Published Research Synopsis: Greenland Melting Finally Measured Directly http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-4213 Anthonares » Blog Archive » Published Research Synopsis: Greenland Melting Finally Measured Directly Tue, 26 Sep 2006 02:45:18 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-4213 [...] Because of the enormous difficulty in measuring the mass of a continental ice sheet, Greenland’s ice mass budget has always been calculated indirectly. Some of the more exciting methods have involved using satellite radar interferometry (discussed here in this previous PRS) to measure the speed of ice sheet flow, but this requires several assumptions that can introduce significant errors. Other methods rely on spotty measurements of ice sheet thickness, snow accumulation, and meltwater discharge that also require lots of assumptions and extrapolation. [...] […] Because of the enormous difficulty in measuring the mass of a continental ice sheet, Greenland’s ice mass budget has always been calculated indirectly. Some of the more exciting methods have involved using satellite radar interferometry (discussed here in this previous PRS) to measure the speed of ice sheet flow, but this requires several assumptions that can introduce significant errors. Other methods rely on spotty measurements of ice sheet thickness, snow accumulation, and meltwater discharge that also require lots of assumptions and extrapolation. […]

]]> By: WaltDe http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-3859 WaltDe Fri, 01 Sep 2006 14:17:45 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-3859 Very good reading. Peace until next time. WaltDe Very good reading. Peace until next time.
WaltDe

]]> By: Anthonares » Blog Archive » The Yellowstone Supervolcano: A Pulsing Malevolance http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-224 Anthonares » Blog Archive » The Yellowstone Supervolcano: A Pulsing Malevolance Sat, 04 Mar 2006 16:16:25 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-224 [...] Interferometry (not for the faint of heart!) Since I’ve been talking about interferometry for the last few weeks (here and here) at Anthonares.net, I thought I would discuss the basic concept very briefly. Waves (like light waves, sounds waves, or ocean waves) travel right through each other, but when they are in the same location at the same time, they interfere. Interference results in the addition of the amplitude of the two waves. So, if two waves are in phase, they interfere constructively and the combined result has a greater amplitude than either wave did to start with. If they are out of phase, meaning the peak of one is aligned with the trough of another, then they interfere destructively and the result has a smaller amplitude than both did originally. [...] […] Interferometry (not for the faint of heart!) Since I’ve been talking about interferometry for the last few weeks (here and here) at Anthonares.net, I thought I would discuss the basic concept very briefly. Waves (like light waves, sounds waves, or ocean waves) travel right through each other, but when they are in the same location at the same time, they interfere. Interference results in the addition of the amplitude of the two waves. So, if two waves are in phase, they interfere constructively and the combined result has a greater amplitude than either wave did to start with. If they are out of phase, meaning the peak of one is aligned with the trough of another, then they interfere destructively and the result has a smaller amplitude than both did originally. […]

]]> By: Anthony Kendall http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-223 Anthony Kendall Thu, 02 Mar 2006 19:11:27 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-223 Today, RealClimate <a href="http://www.realclimate.org/index.php?p=267" rel="nofollow">posted an article</a> that directly mentions the disagreement that mac_davis highlighted between Rignot's paper and that of Johannessen (2005). Basically, the results are not mutually exclusive and Real Climate suggests that Johannessen's estimates are perhaps overestimates because of their inability to measure snow accumulation over certain parts of the ice sheet. Anyway, check out the entry. Today, RealClimate posted an article that directly mentions the disagreement that mac_davis highlighted between Rignot’s paper and that of Johannessen (2005). Basically, the results are not mutually exclusive and Real Climate suggests that Johannessen’s estimates are perhaps overestimates because of their inability to measure snow accumulation over certain parts of the ice sheet. Anyway, check out the entry.

]]> By: Anthonares » Blog Archive » This Month at Anthonares.net: February 2006 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-213 Anthonares » Blog Archive » This Month at Anthonares.net: February 2006 Wed, 01 Mar 2006 03:26:03 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-213 [...] Greenland is melting. Faster. In now hosts some of the fastest moving glaciers in the world and looks to perhaps play a larger role in sea level rise than previously thought. [...] […] Greenland is melting. Faster. In now hosts some of the fastest moving glaciers in the world and looks to perhaps play a larger role in sea level rise than previously thought. […]

]]> By: Anthony Kendall http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-211 Anthony Kendall Tue, 28 Feb 2006 12:34:28 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-211 Mac_davis, Thanks! I'll be keeping an eye on this further, but it's good to hear critical comments on published work based on science rather than supposition. I wonder why the referees did not make sure that the Johannessen results were accounted for. Perhaps this had something to do with the relative recency of the Johannessen paper? Mac_davis,
Thanks! I’ll be keeping an eye on this further, but it’s good to hear critical comments on published work based on science rather than supposition. I wonder why the referees did not make sure that the Johannessen results were accounted for. Perhaps this had something to do with the relative recency of the Johannessen paper?

]]> By: mac_davis http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-210 mac_davis Tue, 28 Feb 2006 09:05:13 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-210 Rignot and Kanagaratnam's paper speculated that snow and ice over other parts of Greenland are melting and the water is flowing into the ocean. Citing other work by Hanna et al. (2004), Rignot and Kanagaratnam figured another 35 km^3 in 1996 and 57 km^3 in 2005 of ice loss occurred from surface melting bringing the total annual loss volume to 91 km^3 in 1996 and 224 km^3 in 2005. This water and ice input leads to a sea level rise of 0.23 ± 0.08 mm/year in 1996 growing to 0.57±0.1mm/year by 2005. Not surprisingly, the reason that is given—presumed—for the melting ice and the rising seas is that temperatures are going up because of global warming. This paper with no reference to Johannessen's paper showing that Greenland is accumulating ice at a rate of about 5.4±0.2cm/year. Johannessen even used data from some of the same satellites. What's more, Johannessen used real data and Hanna et al., cited by Rignot, used a model of surface melt. Consider what would have happened had the latest study included the ice and snow gains observed by Johannessen (and ignored the losses modeled by Hanna et. al.). Johannnessen's increase of 5.4 cm/year averaged over Greenland converts to about 75 km^3/year. Rignot and Kanagaratnam could have subtracted Johannessen's gains. If they had done so, the total volume of ice loss from Greenland would only have become <i>positive</i> during the last 5 years, totaling 17 km^3 in 2000 and 92 km^3 in 2005. This translates to a sea level rise contribution of 0.04mm in 2000 and 0.23mm in 2005—values much less dramatic than those they published. Rignot and Kanagaratnam’s paper speculated that snow and ice over other parts of Greenland are melting and the water is flowing into the ocean. Citing other work by Hanna et al. (2004), Rignot and Kanagaratnam figured another 35 km^3 in 1996 and 57 km^3 in 2005 of ice loss occurred from surface melting bringing the total annual loss volume to 91 km^3 in 1996 and 224 km^3 in 2005.

This water and ice input leads to a sea level rise of 0.23 ± 0.08 mm/year in 1996 growing to 0.57±0.1mm/year by 2005. Not surprisingly, the reason that is given—presumed—for the melting ice and the rising seas is that temperatures are going up because of global warming.

This paper with no reference to Johannessen’s paper showing that Greenland is accumulating ice at a rate of about 5.4±0.2cm/year. Johannessen even used data from some of the same satellites. What’s more, Johannessen used real data and Hanna et al., cited by Rignot, used a model of surface melt.

Consider what would have happened had the latest study included the ice and snow gains observed by Johannessen (and ignored the losses modeled by Hanna et. al.). Johannnessen’s increase of 5.4 cm/year averaged over Greenland converts to about 75 km^3/year. Rignot and Kanagaratnam could have subtracted Johannessen’s gains. If they had done so, the total volume of ice loss from Greenland would only have become positive during the last 5 years, totaling 17 km^3 in 2000 and 92 km^3 in 2005. This translates to a sea level rise contribution of 0.04mm in 2000 and 0.23mm in 2005—values much less dramatic than those they published.

]]> By: Anthony Kendall http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-206 Anthony Kendall Mon, 27 Feb 2006 12:26:14 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-206 mac_davis, Just looking at the abstract of Johannessen's paper, it seems to be in general agreement with what Rignot and Kanagaratnam reported in their paper: snow and ice accumulation is increasing in the deep interior because of increased precipitation, while the ice sheet is thinning along its boundaries due to increased melting and ice calving. mac_davis,
Just looking at the abstract of Johannessen’s paper, it seems to be in general agreement with what Rignot and Kanagaratnam reported in their paper: snow and ice accumulation is increasing in the deep interior because of increased precipitation, while the ice sheet is thinning along its boundaries due to increased melting and ice calving.

]]> By: mac_davis http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-205 mac_davis Mon, 27 Feb 2006 09:42:38 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-205 Hello, I found your site through blogger, and I love how you cited your sources. What do you think about Johannessen et al's paper, <a href="http://www.sciencemag.org/cgi/content/abstract/310/5750/1013" rel="nofollow">here</a>? Hello, I found your site through blogger, and I love how you cited your sources. What do you think about Johannessen et al’s paper, here?

]]> By: Anthony Kendall http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-196 Anthony Kendall Wed, 22 Feb 2006 21:44:05 +0000 http://www.anthonares.net/2006/02/greenland-melting-is-accelerating.html#comment-196 Thanks Tom! It's been a pretty sweet birthday so far. Oh wait, no it's been a pretty normal day. But hey, my car insurance just went down! That's some birthday goodness I can take to the bank. Thanks Tom! It’s been a pretty sweet birthday so far. Oh wait, no it’s been a pretty normal day. But hey, my car insurance just went down! That’s some birthday goodness I can take to the bank.

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