Saturday, October 17, 2009

The Prevarications about Greenland

All the headlines say Greenland is melting.

"Melting Greenland Ice Sheets May Threaten Northeast United States, Canada"
source

"High Water: Greenland ice sheet melting faster than expected and could raise East Coast sea levels an extra 20 inches by 2100 — to more than 6 feet"
source

As ice melts, species will die and new territorial fights emerge
source

Dire predictions for future of Arctic ice
source

Yep, it is close to Halloween and the hysteriacs are about their normal scare tactics. The boogey man is out there waiting to get you in just a few years. Give us money to study this.

The other day I ran across a study that showed that Greenland was subsiding.

"As mentioned earlier, when we use the Ice-3G model for the melting of Pleistocene ice prior to 4000 years ago, and convolve these data with viscoelastic Green's functions, we estimate a viscoelastic uplift of 3.5 ± 2.5 mm/yr at KELY. The uncertainty on this value represents the range of possibilities in our estimate, given the uncertainty in the earth's viscosity profile. If we remove this rate of uplift from the GPS secular subsidence value (~ 5.7 ± 0.9 mm/yr), we obtain an effective elastic subsidence of 9.2 ± 2.7 mm/yr. Tonie van Dam, Kristine Larson, John Wahr, Olivier Francis, " Using GPS and Gravity to Infer Ice Mass Changes in Greenland," Eos Trans. AGU, 81(37), 421
source
accessed 10-16-09

Then I found a powerpoint of a talk showing the measurements of elevation over an 8 year period







When I saw that I thought "That is odd. When you remove ice from a land, like Scandinavia, the land RISES!" Only thicker ice causes subsidence. Less ice causes UPLIFT. So, I looked further. I ran into a 2005 Science article which show that Greenland's ice fields are gaining snow. Yep, you heard it correctly. Greenland, according to this recent study is adding ice, not losing ice.

"A continuous data set of Greenland Ice Sheet altimeter height from European remote Sensing satellites (ERS-1 and ERS-2), 1992 to 2003, has been analyzed. An increase of 6.4 +/- 0.2 centimeters per year (cm/year) is found in the vast interior areas above 1500 meters, in contrast to previous reports of highelevation balance. Below 1500 meters, the elevation-change rate is –2.0 +/- 0.9 cm/year, in qualitative agreement with reported thinning in the ice-sheet margins. Averaged over the study area, the increase is 5.4 +/- 0.2 cm/year, or ~60 cm over 11 years, or ~54 cm when corrected for isostatic uplift. Winter elevation changes are shown to be linked to the North Atlantic Oscillation." Ola M. Johannessen, Kirill Khvorostovsky, Martin W. Miles, Leonid P. Bobylev "Recent Ice-Sheet Growth in the Interior of Greenland," Science 310(2005), p. 1013

How can this be when all the headlines are screaming that Greenland is melting??? What the hysteriacs are doing is looking at the edges of the continent and using that as headlines while they ignore the growth in Greenland's interior. Shame on them. Here is a picture showing ice sheet growth. Notice that only the edges of the continent show thinning. Red is indicative of the ice surface dropping, blue is evidence of the ice surface rising.



The hysteriacs and their followers in the press scream loudly about the tiny amounts of red on the picture above and tell no one about the vast quantities of blue. Shame on this unscientific attitude.

This Science article also has a chart of the growth of the ice sheet over time showing that above 1500 m the ice is getting thicker while below that elevation it is getting thinner, but the over all effect is that Greenland has more ice today thay yesterday, metaphorically speaking.



This finally makes some other data fit. In order for Greenland to melt, the temperature must rise. But NOAA's Global Climate at a Glance site allows pop up charts showing the temperature trends for various spots on earth. Since 2001 central Greenland has been getting colder. Below are some of those pictures.





For a full set of temperature trends in Greenland see greenland-holophobic-fear-is-over

Selective use of data to propel a political agenda is a shameful thing for scientists to do.

3 comments:

  1. Averaged over the study area, the increase is 5.4 +/- 0.2 cm/year, or ~60 cm over 11 years, or ~54 cm when corrected for isostatic uplift.

    Where did they get isostatic uplift?
    Perhaps the average of the study area needs it's correction corrected.
    Start from 60 cm, add subsidence of 9.2 ± 2.7 mm/yr for 11 years, making the corrected figure an average of ~ 70 cm of additional ice load.

    ReplyDelete
  2. They got it from models, not from observation. They say so.

    "Viscoelastic deformations in this region are likely to be relatively large. Using a viscoelastic earth model [Han and Wahr, 1994] and the Ice-3G ice load history [Tushinham and Peltier, 1991], the viscoelastic crustal uplift predicted at the southwestern edge of the ice sheet is estimated to be about 3.5 ± 2.5 mm/yr."
    Tonie van Dam, Kristine Larson, John Wahr, Olivier Francis, " Using GPS and Gravity to Infer Ice Mass Changes in Greenland," Eos Trans. AGU, 81(37), 421

    Unfortunately, science has become an endeavor of building models rather than actually looking out the window or observing the direction of ground motion.

    Other articles show subsidence as well.

    "We analyze data from seven continuous Global Positioning System (GPS) receivers and one tide gauge, all located along the edge of the Greenland ice sheet, to determine vertical uplift rates. We compare our results with predictions based on the ICE-5G deglaciation model of Peltier (2004). Results from the GPS receiver at Kellyville (-1.2 ± 1.1 mm/a) and from the tide gauge at Nuuk (-2.2 ± 1.3 mm/a), indicate that ICE-5G overestimates the subsidence rates at those locations by 2.1 and 1.1 mm/a, respectively."
    Sjfaqat Khan et al, "Geodetic measurements of postglacial adjustments in Greenland Journal of geophysical research 2008, vol. 113, noB2

    "For the central site Kangerlussuaq a negative uplift rate (subsidence) of (−3.1 ± 1.1) mm yr−1 was obtained, related to the reference frame IGb00. "R. Dietrich Present-day vertical crustal deformations in West Greenland from repeated GPS observations"Geophysical Journal International Volume 163 Issue 3, Pages 865 - 874


    "We have analyzed 5 years of continuous Global Positioning System (GPS) measurements taken at Kellyville, just off the western margin of the ice sheet in southern Greenland. A fit to the vertical component gives a negative secular uplift rate of −5.8 ±1.0 mm/yr. A negative rate (i.e., a subsidence) is consistent with archeological and historical evidence that the surrounding region has been subsiding over the last 3 kyr. "John Wahr et al, "GPS measurements of vertical crustal motion in Greenland," J. Geophys. Res., 106(D24), 33,755

    Subsidence, of the rates noted are not compatible with removing the ice.

    ReplyDelete
  3. That's good. I thought for a minute there the warmers were just making stuff up.

    They got it from models, not from observation.

    Wait. What?

    ReplyDelete