Guest essay by Larry Hamlin

Total ice loss from latest study is “consistent” with, not “double” prior study measurements

Numerous recent climate alarmist articles addressing the recent study results reported for the new CryoSat-2 radar altimeter satellite methodology with increased land area orbital coverage capability for evaluating ice loss in Antarctica between 2010 and 2013 have made a monumental blunder in their reporting.

http://www.theguardian.com/environment/2014/may/19/doubling-of-antarctic-ice

-loss-revealed-by-european-satellite

The big scary headline claim in almost all of these alarmist articles which screamed that the rate of Antarctica ice loss has “doubled” compared to prior estimates is wrong. The alarmist reporters have managed to confuse two distinct issues addressed in this latest study which dealt with both continental Antarctic ice loss as well as the contribution of this Antarctica ice loss to sea level rise.

This latest study (abstract link below) clearly establishes that the continental Antarctica ice loss estimates based on past satellite gravimetry surveys are “consistent” with the latest study radar altimetry total ice loss findings. Specifically the full study says:

“At the continental scale, the most recent estimates of Antarctic ice sheet mass balance are based solely on satellite gravimetry surveys [Barletta and Bordoni, 2013; Velicogna and Wahr, 2013; Williams et al., 2014]. According to these studies, the rate of ice mass loss from Antarctica has increased progressively over the past decade and, between 2010 and 2012, fell in the approximate central range 105 to 130 Gt yr-1. Our survey puts the contemporary rate of Antarctic ice sheet mass loss at 159 ± 48 Gt yr-1, a value that, although larger, is nevertheless consistent given the spread of the gravimetry-based uncertainties (16 to 80 Gt yr-1). A possible explanation for the discrepancy is the exceptional snowfall event of 2009, which saw an additional ~200 Gt of mass deposited in East Antarctica [Boening et al., 2012; Lenaerts et al., 2013; Shepherd et al., 2012] that, although absent from the CryoSat-2 record, does factor in the gravimetry-based estimates of imbalance.”

http://onlinelibrary.wiley.com/doi/10.1002/2014GL060111/abstract

Amazingly then and despite the bogus climate alarmist headlines to the contrary this latest study of Antarctica ice loss using new radar altimetry technology demonstrates that the total continental ice loss of Antarctica is “consistent” with prior measurements using gravimetry measurement technology.

The climate alarmist reporters misunderstood the total Antarctica ice loss picture from this latest study and provided incorrect information in their articles. They appear to have confused this latest studies reported sea level rise contribution estimate of 0.45 mm per year which is about “double” prior study estimates of 0.19 mm per year as being applied to ice loss values which is incorrect.

Additionally these alarmist articles completely fail to provide any distinction regarding the significant differences between the measured ice loss rates for the three distinct regions of Antarctica addressed in this study.

Over 98 percent of the total ice loss defined in this latest study is associated with the unstable West Antarctica and the Antarctic peninsula with West Antarctica alone representing about 85 percent of the total ice loss measured. These combined regions of Antarctica contain only about 10 percent of the total Antarctic ice mass.

The ice loss reported in this study for the massive Eastern Antarctica region which contains about 90 percent of the total Antarctica ice mass represents less than 2 percent of the total ice loss reported (-3 +/- 36 Gt. per year) with the uncertainty band being ten times greater than the nominal ice loss value reported. This outcome continues to support the findings of other studies, discussed below, of the ice loss in this region which have concluded that Eastern Antarctica is a more stable region of Antarctica which has not experienced significant ice loss and in fact has seen periods of significant increasing snow and ice accumulation.

One study (abstract link below) of Eastern Antarctica notes:

“In this study, we describe the causes and magnitude of recent extreme precipitation events along the East Antarctic coast that led to significant regional mass accumulations that partially compensate for some of the recent global ice mass losses that contribute to global sea level rise. The gain of almost 350 Gt from 2009 to 2011 is equivalent to a decrease in global mean sea level at a rate of 0.32 mm/yr over this three-year period.”

http://onlinelibrary.wiley.com/doi/10.1029/2012GL053316/abstract

Another study (abstract link below) of East Antarctica notes:

“During 2003 to 2008, the mass gain of the Antarctic ice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 Gt/yr (2.5% of input), as derived from ICESat laser measurements of elevation change.” “The recent 90 Gt/yr loss from three DS (Pine Island, Thwaites-Smith, and Marie-Bryd Coast) of WA exceeds the earlier 61 Gt/yr loss, consistent with reports of accelerating ice flow and dynamic thinning. Similarly, the recent 24 Gt/yr loss from three DS in the Antarctic Peninsula (AP) is consistent with glacier accelerations following breakup of the Larsen B and other ice shelves. In contrast, net increases in the five other DS of WA and AP and three of the 16 DS in East Antarctica (EA) exceed the increased losses.”

http://onlinelibrary.wiley.com/doi/10.1002/grl.50559/abstract

This latest study concludes that the majority of the Antarctica ice loss results reflects the behavior of the unstable West Antarctica region. It is in fact the West Antarctica region which experienced the 31 percent increasing ice loss relative to prior study measurements.

Concerning this latest studies much lower ice loss measurements in both Eastern Antarctica and the Antarctic Peninsula the study provides a caution concerning the difficulty of obtaining accurate measurements in these regions noting:

“the average change in ice sheet mass remains small in comparison to expected fluctuations in snow accumulation (Table 1), which present an observational challenge to all geodetic techniques. Although the CryoSat-2 measurements allow an improved understanding of the drivers and timescales of ice sheet imbalance in these sectors, longer-period data sets are required to separate the effects of meteorological and ice dynamical imbalance [Wouters et al., 2013].”

The most recent satellite derived global sea level rise study available (abstract link below) determined that the rate shows no acceleration whatsoever in the period from 1992 to 2011 and amounts to only about 7 inches per century. Specifically this sea level rise study notes:

“We use 1277 tide gauge records since 1807 to provide an improved global sea level reconstruction and analyse the evolution of sea level trend and acceleration.” “The new reconstruction suggests a linear trend of 1.9 ± 0.3 mm·yr- 1 during the 20th century, with 1.8 ± 0.5 mm·yr- 1 since 1970.”

http://www.sciencedirect.com/science/article/pii/S0921818113002750#f0015

The authors of this latest Antarctica ice loss study estimate that the rate of global sea level rise contributed by their measured Antarctica ice loss results is about 0.45 mm per year which is about the thickness of a human fingernail.

The authors note that the higher sea level rise estimate from this studies ice loss measurements compared to prior study sea level rise contribution estimates of 0.19 mm per year “reflects both the improved capability of CryoSat-2 to observe regions of ice dynamical imbalance, and the impact of short- and intermediate-term changes in ice sheet mass.”

The alarmist articles in the news about the results of this latest Antarctica ice loss study incorrectly claimed that the rate of Antarctica ice loss was “double” prior study estimates which is wrong, failed to provide this studies information showing the rate of total measured ice loss was “consistent” with prior total ice loss estimates, failed to identify the significant distinctions between the ice loss behavior between the unstable West versus more stable East Antarctica regions, failed to identify that the majority of the ice loss measured was from the unstable West Antarctica region, failed to identify that it was the West Antarctica region that had experienced an increased ice loss rate compared to prior studies and failed to identify the reasons indicated in this study which account for the increased estimate of sea level rise.

Share this: Print

Email

Twitter

Facebook

Pinterest

LinkedIn

Reddit



Like this: Like Loading...