Tuesday, December 4th 2012, 2:42 AM EST
A new report says that Glaciers are melting, but not as fast as some say. In fact, Antartica is gaining almost as much ice as it loses.
A new “comprehensive” report about the melting of Antarctic and Greenland ice sheets is being touted by climate alarmists as “grim news” but in fact says no such thing. This latest estimate, published this week in Science, combines data from many sources including 20 years of satellite data and 32 years of ice-sheet simulations to arrive at a mixed conclusion. It estimates that, between 1992 and 2011, the Antarctic and Greenland ice sheets lost 1350 ± 1010 and 2700 ± 930 Gt of ice, respectively. That is equivalent to an increase in global mean sea level of 11.2 ± 3.8 mm, less than 1/2 an inch. Moreover, while some areas were loosing ice mass others were gaining mass from snowfall. The East Antarctic Ice Sheet (EAIS), which occupies over 75% of Antarctica, experienced mass gains during the final years of the study.
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The intent of this new report is quite clear, come up with an unassailable new estimate for ice loss that can be included in the next IPCC global warming report. In “A Reconciled Estimate of Ice-Sheet Mass Balance,” Andrew Shepherd et al. begin with some historical perspective. “Analysis of the geological record suggests that past climatic changes have precipitated sustained ice-sheet contributions, in excess of 10 mm year−1 over millennial time periods, and the prospect of such changes in the future are of greatest concern,” they state, accurately stating that there has been significant variation in ice-sheet loss and ocean levels before the specter of anthropogenic global warming raised its climate destroying head.
Naturally, the authors could not resist bowing to the dominant consensus driven, group think pap: “Even the modest rises in ocean temperature that are predicted over the coming century could trigger substantial ice-sheet mass loss through enhanced melting of ice shelves and outlet glaciers. However, these processes were not incorporated into the ice-sheet models that informed the current global climate projections.” Their data may not be reconciled but the authors are certainly demonstrating that they are go-along types of climate scientists. Exactly how they performed this extensive and exhaustive study is stated early on in the Science paper:
In this assessment, we use 19 years of satellite radar altimeter (RA) data, 5 years of satellite laser altimeter (LA) data, 19 years of satellite radar interferometer data, 8 years of satellite gravimetry data, 32 years of surface mass balance (SMB) model simulations, and estimates from several glacial isostatic adjustment models, to produce a reconciled estimate of ice-sheet mass balance. The satellite data sets were developed by using independent methods and, in the case of the LA, gravimeter, and SMB data sets, through contributions from numerous research groups. To enable a direct comparison, we reprocessed the geodetic data sets with use of common time intervals and common definitions of the East Antarctic, West Antarctic, Antarctic Peninsula, and Greenland ice-sheet (EAIS, WAIS, APIS, and GrIS, respectively) boundaries (16). The maximum temporal extent of the satellite data sets spans the period 1992 to 2011, and results from all geodetic techniques are available between January 2003 and December 2008. Unless stated otherwise, all results are presented with 1-sigma uncertainty estimates.
Click source to read FULL report from Doug L. Hoffman