<div>Spokesman-Review article from today mentioned in subject heading pasted in at bottom.</div>
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<div>As is well known to students of climate science, and often ignored by those with an agenda to dismantle the credibility of modern climate science, the primary data for climate predictions regarding future impacts from human influences is Earth's paleoclimate history, not results from computer models. Computer models are merely tools that must predict the paleoclimate data if they are to be regarded as reliable to make predictions for the future. Consider this recent research from the Goddard Institute for Space Studies to elucidate my point:</div>
<div><a href="http://www.giss.nasa.gov/research/briefs/hansen_15/">http://www.giss.nasa.gov/research/briefs/hansen_15/</a></div>
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<h3>Earth's Climate History: Implications for Tomorrow</h3>
<p class="byline">By James E. Hansen and Makiko Sato — July 2011</p>
<p class="byline">Contrary to popular belief, climate models are not the principal basis for assessing human-made climate effects. Our most precise knowledge comes from Earth's paleoclimate, its ancient climate, and how it responded to past changes of climate forcings, including atmospheric composition. Our second essential source of information is provided by global observations today, especially satellite observations. which reveal how the climate system is responding to rapid human-made changes of atmospheric composition, especially atmospheric carbon dioxide (CO<sub>2</sub>). Models help us interpret past and present climate changes, and, in so far as they succeed in simulating past changes, they provide a tool to help evaluate the impacts of alternative policies that affect climate. </p>
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<div>The comments above from GISS scientists are consistent with the methods used by the scientists who just published the</div>
<div>following paper in Geophysical Research Letters, discussed in the Spokesman Review today, “Interannual to multidecadal Arctic sea ice extent trends in a warming world.”</div>
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<div>They ran the computer model with 4000 years worth of climate history data to determine how well the model predicted empirical facts of Earth's past climate.</div>
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<div>For some reason, every time I've tried to access the AGU website below to read the abstract for this paper, the website shut down generating an error message; but the website was clearly providing information on this exact paper under discussion. However, this AGU website offers a brief discussion of the paper: <a href="http://www.agu.org/news/press/pr_archives/2011/2011-27.shtml">http://www.agu.org/news/press/pr_archives/2011/2011-27.shtml</a><br>
<br><a href="http://m.spokesman.com/stories/2011/aug/15/study-of-ice-melt-fixes-humans-role/" target="_blank">http://m.spokesman.com/stories/2011/aug/15/study-of-ice-melt-fixes-humans-role/</a></div>
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<div><a href="http://www.agu.org/pubs/crossref/2011/2011GL048008.shtml" target="_blank">http://www.agu.org/pubs/crossref/2011/2011GL048008.shtml</a> </div>
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<h1>Study of ice melt fixes humans’ role</h1>
<p><strong>Richard Mauer</strong> McClatchy </p>
<p>August 15, 2011</p>
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<p>ANCHORAGE, Alaska – About half the recent record loss of Arctic sea ice can be blamed on global warming caused by human activity, according to a new study by scientists from the nation’s leading climate research center.</p>
<p>The peer-reviewed study, funded by the National Science Foundation, is the first to attribute a specific proportion of the ice melt to greenhouse gases and particulates from pollution.</p>
<p>The study used supercomputers and one of the world’s most sophisticated climate models to reach its conclusions, said lead author Jennifer Kay, a staff scientist at the National Center for Atmospheric Research in Boulder, Colo. The paper was published last week in the scientific journal Geophysical Research Letters.</p>
<p>Kay said her study was an attempt to learn how much Arctic Ocean melting can be attributed to “natural variability” – complex changes wrought by nonhuman forces – and how much has been caused by greenhouse gases such as carbon dioxide and by atmospheric particulates.</p>
<p>In doing so, she was also able to look ahead to future annual and decade-long fluctuations. She and the other authors said conditions will become more volatile from year to year. That means there will be years and perhaps decades when the ice pack expands. But the trend is in the other direction.</p>
<p>“There’s no doubt about it: sea ice is going away,” she said. “What we found was that about half of that trend is related to the increasing greenhouse gases.” The other half of the sea-ice loss, as observed over the late 20th century, was “just related to variability in the system.”</p>
<p>The study comes at an important time as public policy and climate change intersect in Alaska and elsewhere in the North. The reduction of the ice pack is already opening Arctic waters to transportation, development and military activities. The NCAR study says that the melting of the ice pack is no short-term fluke but an actual change in climate.</p>
<p>In the study, the authors said earlier research determined that greenhouse gases were responsible for some loss of sea ice, but no one had been able to firmly establish how big a part they played.</p>
<p>Kay said the climate model she chose, Community Climate System Model version 4, had been developed by teams of scientists over several decades. She ran 4,000 years’ worth of data through the model, a period when volcanoes, solar variations and other factors were known or believed to have caused climate changes.</p>
<p>The scientists placed extra focus on the years since 1979, when satellite images became available to determine the extent of sea-ice depletion.</p>
<p>The model accurately “predicted” what actually occurred historically, validating the method, she said.</p>
<p>But more to the point, by replaying the climate forces of the 20th century over and over through the model, the scientists were able to show that variability can account for only half the loss of ice, she said.</p>
<p>That means that if humans were still only hunters and gatherers, sea ice might have retreated anyway over the past 30 years.</p></div></div></div>
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<div>Vision2020 Post: Ted Moffett<br></div>