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Anthropogenic Climate Change Exists

Correlation plus a theory is not proof CO2 dominates climate My opponent noted temperature generally rising since 1900 and CO2 rising since 1900, and claims that because CO2 is a greenhouse gas, it must be responsible for the rise. The error in that logic is that we do not know how much of the rise is due to CO2 and how much is due to other factors affecting climate. We could plot increasing consumption of charcoal in backyard barbecues, noted that burning charcoal heats the atmosphere, and then concluded that barbecuing causes global warming. The barbecue theory is defeated by showing that there isn't enough heat generated by the volume of charcoal consumed to have a significant warming effect. Similarly, Pro offers no analysis that shows CO2 to be even a significant cause. Pro has the burden to prove not only that CO2 dominated climate in the last century, but that it will dominate the next century despite all unknown factors affecting climate. Here is a reconstruction of CO2 and climate over the past 650 million years. [1. http://www.geocraft.com...] http://www.debate.org... Over geological time, clearly climate has been dominated by factors other than CO2. On the geological time scale, we are currently in an unusual period of low temperatures and low CO2. It a very complicated picture, proving that climate is far more than just CO2. Pro shows the CO2 data for the past 650,000 years.Temperature follows the same pattern, only CO2 follows temperature. The graphs are here [2. http://www.geocraft.com...] If the graphs are time aligned, the result is not that CO2 causes warming. Quite the opposite, CO2 rises about 800 years after temperature rises. Warming causes CO2 because warmer oceans cannot dissolve as much CO2. In 2013 the prestigious journal Nature published an up to date scientific reconstruction of climate for the past 2050 years. [3. http://www.nature.com...] It shows that over the period climate varied by about as much as the present warming, with both the Roman Period and the Medieval Warm Period warmer. It remains possible that CO2 is contributing significantly to current warming, but the natural variations are so large that CO2 might be inconsequential. Current climate science has no explanation for the major climate variations of the past 2000 years. That's why the discredited global warming hockey stick attempted to prove there were no past variations. Pro has the burden to prove CO2 dominates. I say it's unlikely CO2 dominates, but no one really knows. http://www.debate.org... Total sea ice is at record levels and CO2 can't explain why Pro argues that arctic ice is melting, that proves CO2 is the cause. Historically, Arctic ice melts when Antarctic ice increases in a cycle of 40 to 60 years called the Pacific Decadal Oscillation (PDO). The PDO pattern fits the cooling period from the 40s to the 70s that CO2 cannot explain. [4. http://www.drroyspencer.com...] The Arctic was last clear around 1940. Global warming alarmist scientists warned that this time the Antarctic was melting as well, and they made the confident prediction in 2010 was that the Antarctic would be ice free by 2013. What actually happened is that the Antarctic reached record high levels of ice: “The Antarctic surge is so big that overall, although Arctic ice has decreased, the frozen area around both poles is one million square kilometres more than the long-term average.” [5. http://www.dailymail.co.uk...] If CO2 warming dominates climate, it cannot be that it is overwhelmed by other factors like the PDO. But it is. CO2 theory cannot explain the pause in warming To accurately predict future climate, computer models must be proved to be reliable. We know the models did not predict ice formation in the Antarctic nor pre-1900 climate variations. In addition, global warming has essentially ceased since 1997, [6. http://wattsupwiththat.com...] so a check on the accuracy of climate models is how well this pause is predicted. Sscientists predicting CO2 crisis use many variations of computer models. The collections are called CMIP3 and CMIP5, with CMIP5 the very latest. ... Climate models cannot simulate past surface temperatures, precipitation or sea ice area. Those are basic components of Earth’s climate. … The concern about the latest slowdown in warming was addressed by a recent scientific study by Von Storch, et al. (2013) “ Can Climate Models Explain the Recent Stagnation in Global Warming? ” The one-word answer to the title question of their paper is, “No”. They stated: However, for the 15-year trend interval corresponding to the latest observation period 1998-2012, only 2% of the 62 CMIP5 and less than 1% of the 189 CMIP3 trend computations are as low as or lower than the observed trend. Applying the standard 5% statistical critical value, we conclude that the model projections are inconsistent with the recent observed global warming over the period 1998- 2012. [7. Tisdale, Bob (2013-09-23). Climate Models Fail (Kindle Locations 276-291)] The Von Storch paper is available free in draft format [8. http://www.mpimet.mpg.de...] There are a number of ocean oscillations in addition to the PDO. These are not accurately modelled in the computer simulations and likely account for the rapid warming before the current pause. The Medieval Warm Period and the following Little Ice Age correlate extremely well with sunspot activity, but no physical cause of the warming and cooling has been definitively linked to sunspots so there is nothing in the computer models representing the effects. It is not direct change in the solar radiation, because that varies too little to explain the large effect. Danish scientist Svensmark has proposed that changes in cosmic rays linked to variations in sunspots affect cloud cover by a cloud seeding mechanism, but CO2 scientists discount that, so nothing is in the computer models. [9. http://wattsupwiththat.com...] All of the climate change in the past century could be accounted for by less than a 3% change in cloud cover, but even with satellites cloud cover measurement is difficult. The cloud height is important as well as the density. We don't know future CO2 levels Everyone, crisis advocates and skeptics alike, agrees that whatever the CO2 sensitivity it is logarithmic. So if doubling CO2 produces a one degree rise, which is about the theoretical rise if there is nothing in the climate that magnifies the effect, then doubling it again would produce another degree of warming. An exponential rise in CO2 produces a linear rise in temperature. If we had a perfect model of CO2 effects on climate, we would still need to know how much CO2 is left to be produced and at what rate. Everyone agrees oil and coal are running out, but no one is sure how fast. But as supplies get scarce, prices rise and alternatives become economically viable. A technological breakthrough like a cheap, efficient battery would drop carbon consumption dramatically. It's another major unknown. A clarification of the resolution was agreed to in the debate comments so Pro must show that CO2 dominates climate in the past and future century. Pro has not made a convincing case that CO2 accounts for past climate change, nor that either computer models or carbon consumption assumptions are reliable enough to predict the future. He has the burden of proof.