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" The Arctic Ocean was last ice-free in summer millions of years ago, and it seems nearly that long since NASA climate scientist James Hansen first testified to Congress on the dangers of global warming in 1988. Now, legislators are preparing a bill to limit carbon emissions, but, speaking at a World Science Festival panel discussion in New York City last night, Hansen said the House&amp;#039;s Markey-Waxman bill wasn&amp;#039;t worth the wait. &amp;quot;It&amp;#039;s a fake,&amp;quot; he said, &amp;quot;because it will still allow the building of more coal-fired power plants.&amp;quot; (Hansen also said he favored legislation that would gradually raise prices for carbon emissions while providing rebates to consumers, giving individuals financial incentives for reducing their own climate impacts.) The roundtable session, called &amp;quot;Carbon Conundrum,&amp;quot; took place in front of an audience of about 150 on day two of the World Science Festival. The seven panelists, who included biologists, policy analysts, and environmental activists, also spoke about upcoming international negotiations, new climate-change projections and a movement to set the eventual level of carbon dioxide in the atmosphere lower than it is today. The most interesting insight expressed may have been biologist Thomas Lovejoy&amp;#039;s take on carbon sequestration: &amp;quot;The best way to take carbon of the atmosphere with no downside is biology,&amp;quot; he said. Deforestation and soil erosion have released about 200 billion tons of carbon in recent centuries, he said, while reforestation &amp;quot;could put about 150 billion tons back into living ecosystems&amp;quot; in the next half-century. Kyoto Protocol, Take 2 The toughest wrestling tournament of 2009 could be the climate negotiations coming up in Copenhagen in December, where the governments will wrangle over the successor to the 1992 Kyoto Protocol. The roundtable audience saw a demonstration of a software package to be used by negotiators as a sort of combination instant replay and scoring machine. It&amp;#039;s called C-ROADS, for Climate Rapid Overview and Decision Support, and it uses a highly simplified version of current climate models to provide near instantaneous climate predictions based on changing variables. What if Indonesia agrees to stop cutting rain forests by 2015? The United States swears off coal? The Maldives promises (as the archipelago nation did this spring) to cut its already inconsequential emissions to zero? You can plug all that into the simulator and get a read on how it will affect climate change over the coming century. The system is already being used in meetings that are lead-ups to the Copenhagen talks.  350 ppm: The Goal for Stabilized CO2 Levels Of the tangle of numbers describing the arcana of climate science--the albedo effect, radiative forcing, surface temperature anomalies and many more topics--one figure stands alone for its clarity, importance and ability to stand in for other factors: The concentration of carbon dioxide in the atmosphere. Preindustrial levels were 280 ppm; we&amp;#039;re now at 387ppm; projections for the year 2100 have ranged from about 470ppm to more than 1000 ppm.  The panelists all called for a return to a level of 350 ppm million. &amp;quot;This is not a future problem. We have to scramble, not to stop global warming, but to stop it short of utter chaos,&amp;quot; said author and activist Bill McKibben. His group, 350.org, is organizing public events on October 24, in advance of the Copenhagen meetings. Food Supplies and Global Warming David Battista, a University of Washingon professor, showed slides projecting that later this century, average temperatures across most of the globe will exceed the highest temperatures ever recorded at those locations. This, he said, would lead to steep declines in food production. &amp;quot;Between the latitudes of 30 degrees north and 30 south there are already a billion malnourished people today,&amp;quot; he said. But increasing heat could bring &amp;quot;30 to 40 percent decline in crop yields&amp;quot; by mid-century in places where the population may rise by 50 percent.  The Changing Ocean &amp;quot;If the changes in the Arctic were taking place in New York City, everyone would get on board very quickly,&amp;quot; said Julienne Stroeve, a researcher with the National Snow and Ice Data Center in Colorado. &amp;quot;The rate of change up there is astounding, and we have to get below the current carbon dioxide levels.&amp;quot; While earlier studies projected that the Arctic Ocean could be ice-free by mid-century, Stroeve said that the real date could be 2030. &amp;quot;We&amp;#039;re about 30 years ahead of where the ice should be, according to the models.&amp;quot; Marine botanist Sylvia Earle discussed bad news in ocean acidification (initially unanticipated, now accelerating) and ocean floor methane (closer to being released into the atmosphere due to warming waters), then reviewed the evils of trawlers (&amp;quot;It&amp;#039;s like using bulldozers to catch a few squirrels--you throw away the forest and get back a few pounds of protein&amp;quot;). In an echo of Lovejoy&amp;#039;s point about natural carbon sequestration, she said, &amp;quot;We have to protect the integrity of natural systems so they can continue to do what they have always done, for many hundreds of millions of years.&amp;quot;  RELATED STORIES * EARLIER: Methane Hydrates and Climate Change  * QA: Global Warming, Greenland and Oil  * PLUS: Drilling the Ocean for Future Climate Clues  * FOLLOW US: Popular Mechanics is Now on Twitter!  * FRIEND US: Find PM on Facebook   "^^<http://www.w3.org/2001/XMLSchema#string>
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