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Anthropogenic Climate Change Exists

Since 2000, CO2 has risen by 54% with no increase in global temperatures. Why? Pro cannot provide a good answer to that question, and neither can the IPCC. The theory that CO2 dominates climate is therefore wrong. It may be that CO2 is contributing to warming at some level, but that a greater cooling factor is swamping the CO2 effect. If that's the case, there is no basis for supposing that CO2 will dominate climate in the future, because whatever cooling dominated the past 17 years may be the same or greater in the future. The IPCC cannot explain why a 54% increase in CO2 produced no increase in temperature. As described in [8], Von Storch systematically ran all the IPCC computer models of the climate, and found that the actual temperatures for the last 17 years fell outside the model predictions. That's after the models had been tweaked using knowledge of the lack of global warming. The models still could not describe the past, so clearly they cannot be counted on to predict the future. Pro only offers at base the fallacious logic that correlation means causation. But when CO2 increases by 54% in the past 17 years, and there is no increase in global temperature, then even the correlation claim fails. Solar activity correlates well with global temperature for the past 17 years, for the entire 20the century and for as long as records of sunspot activity have been kept, which is back through the Middle Ages. Solar activity is discounted by CO2 theorists on the grounds that the measured irradiance of the sun, i.e.. the heat output, has not changed enough in recent decades to account for the temperature changes. However, solar activity produces changes in cosmic ray levels, and there is a theory that cosmic rays have an effect that changes cloud cover. The solar cosmic ray theory is also one of correlation, and cannot be considered causation until the mechanism is proved. However, unlike CO2 theory, the correlation actually holds over long and short periods. There is a close correlation of solar sunspot activity and global temperature for the past century. [10. http://www.tmgnow.com...] The past 17 years has been at the leveling off and start of a downward trend in sunspots after a period of increase during the 1980s and 1990s. [11. http://notrickszone.com...] Historical reconstruction shows CO2 does not dominate climate I pointed to reconstructions of climate for the distant past and the for the past 2000 years to show that climate has varied more than in recent years, and without any apparent relation to atmospheric CO2 levels. Pro argues that past climate doesn't count because we are only discussing the past century and the next century. Past climate counts because the laws of physics do not change at all over time. Consequently, if factors other than CO2 have always dominated climate, then it's unreasonable to suppose that a new CO2-only physics began recently. Pro's principle argument is that correlation proves causation. If there was no such correlation in the past, that is not sustained. Since the chance correlation only applies for a short time, it's important to Pro's case that we not look at the hundreds, thousands, and millions of years when there was no such correlation. Here are the two climate reconstructions referenced in the previous round: The climate of the past 2000 years shows there is nothing special about the past century. Climate has always been changing by about as much as in the past century, and often more. Global warming hockey stick discredited The global warming hockey stick was presented in the 2000 IPCC report. It purported to show that the Medieval Warm Period and the Little Ice Age were local to Europe and that climate had not changed substantially in the past 1000 years, until the warming from 1983-1997. The statistical error used in the calculation yielding the hockey stick was discovered by McKitrick. [12. "The Mann et al Northern Hemisphere 'Hockey Stick': A Tale of Due Diligence." published in "Shattered Consensus" edited by Patrick Michaels]. A good summary by a scientist who believes in human-caused global warming is from the MIT magazine Technology Review. [13. http://www.technologyreview.com...] The Wikipedia article, heavily biased towards CO2 theory claims that the hockey stick has since been proved because a recent analysis shows that recent temperatures were higher than the Medieval Warm Period [14. http://en.wikipedia.org...] However, the accompanying graph shows that the MWP and the Little Ice Age existed as worldwide climate change, which is what the hockey stick was mainly supposed to disprove. The most recent reconstruction [3] clearly disproves the hockey stick. CO2 follows temperature increase That CO2 lags temperature in past climate is well known, but I apologize for giving the wrong link in the previous round. A journal article published in 2012 gives the result: “Our analyses of ice cores from the ice sheet in Antarctica shows that the concentration of CO2 in the atmosphere follows the rise in Antarctic temperatures very closely and is staggered by a few hundred years at most,” - Sune Olander Rasmussen [15. Watt provides graphs and links the Rasmussen paper http://wattsupwiththat.com...] Another set of graphs showing the lag is given at [16. http://joannenova.com.au...] Total sea ice is at a high Pro argued that shrinking Arctic ice proved that CO2 causes global warming. I pointed out that Antarctic ice is expanding, contradicting CO2 theory, and in keeping with the historically observed Pacific Decadal Oscillation (PDO). Pro responded that the ice doesn't melt until above the freezing point. Sure, but how was melting Arctic ice supposed to prove CO2 theory? The Antarctic ice has rapidly expanded since 2010, when Al Gore predicted it would be all gone by 2013. What this proves is that CO2 is not dominating climate. The natural PDO, not in the CO2 climate models is dominating the ice levels. The PDO seems to be linked to the second of three overlapping solar cycles, but the causation is unproved. Future CO2 levels are unknown I noted that even if CO2 dominates climate, there is no confident prediction of future CO2 levels. Nearly everyone agrees that the world is running out of fossil fuels, so there is an aggressive search for alternatives. A technological breakthrough, or a simple substantial rise in the price of oil could substantially lower the rate of CO2 increase. Pro did not respond.