Global warming is likely (and mostly) anthropogenic

1. Correlation and Causation My opponent’s main argument is that correlation is not equal to causation, and I totally agree. However, some degree of correlation is needed to prove causation. The more robust the correlation, the more likely some causation exists. I have provided a large amount of data, simplified and shortened, which shows an excellent correlation between carbon dioxide and CO2 based on academic studies. Now, in science, many correlations have become nearly accepted facts. For example, enough data has been found showing that smoking causes cancer [1], based on correlations. Now, if we look at the raw data we could argue warming causes the CO2 increase (which is what my opponent argues later). And, looking at the raw data, cancer may cause smoking. The question is if these correlations hold up to scrutiny. My opponent then cites co2science.org noting that CO2 lags temperature. Whether or not it is true, looking at these paleoclimatology correlations partially proves AGW. So, let’s assume CO2 actually does lag temperature. This does not disqualify CO2 as a driver, even a large driver, for climate change. Now, in the last 100,000 years the warming phases last around 5000 years (we are in one now—and have been for a few thousand years). The CO2 lag is only 800 years long. The lag ignores one important point: “[a]ll that the lag shows is that CO2 did not cause the first 800 years of warming, out of the 5000 year trend. The other 4200 years of warming could in fact have been caused by CO2, as far as we can tell from this ice core data.”[2] Even if we assume CO2 didn’t cause the rest of that warming, this still does not disqualify its ability to be an amplifier [3]. For 600,000 years Co2 has not been at the levels it has been today [4]. So, since the amount of CO2 is much larger now than it was throughout most interglacials, we can easily argue this current warm period has made this amplifier stronger than it has ever been. At least, for 600,000 years. 2. Oceans cause the CO2 rise? This is highly unlikely. Unless my opponent agrees this warming is unprecedented (which kind of concedes the debate for him…) it is hard to say oceans can cause record CO2 levels. There are two strong lines of evidence against this: First, O2 is decreasing in the atmosphere. If the Ocean is emitting CO2, the amount of O2 would not decrease—but CO2 levels would still rise. Cars, however, use oxygen in their fuel systems and burn out Carbon Dioxide. The fact O2 is falling shows something that uses O2 is causing this decrease—which is most likely not a natural source. Second, the known fossil fuel burning easily fulfills the amount of CO2 increase. CO2 increases every year about 16 billion tonnes per year. Humans, on average, emit 30 billion tonnes of CO2. Half of our CO2 is soaked up by oceans (yes, they have stored CO2). So, unless nature through some other mechanism can soak up nearly all of our emissions, it is unlikely the ocean plays a larger role than man in the increase in CO2 [5]. Another line of evidence is the temperature itself. The temperature increase is erratic because natural factors (mainly, PDO and volcanoes) play short term roles in our climate. The CO2 increase is fairly linear, non-erratic, and consistent [6]. If the Ocean emits CO2 due to temperature increases, we should see some large variation, then, if the ocean is the cause. Even if it is not as great as the temperature fluctuation. We have not seen this variation if we are to expect a natural cause emitting most of the modern CO2. My opponent has provided insight opposing my amplifier argument under #1. A new paper by Shakun et al. 2012 has found CO2 often leads temperature, and ended the ice age (was a leading factor in its end), and amplified and sometimes controlled warming and cooling in our current interglacial [7]. And the fact CO2 has warming properties as a greenhouse gas [8], saying it has no effect, or no amplification, is unbelievable. 3. Past climate I agree that climate has changed, will change, and is changing. I will not, and can not, deny this. But saying climate has changed does not tell me why it has changed. One study pointed out, “Correlation of CO2 levels with estimates of palaeoclimate suggests that the atmospheric greenhouse effect has been a major factor in controlling global climate over the past 600 million years.”[9] If anything, the paleoclimatology merely shows and proves that greenhouse gases control and amplify past warmings. And, I would like to note, the study cited has a longer time frame then any of my opponents graphs… Further, the warming in my opponent’s graph, the medieval warm period, has been exaggerated and was a local phenomenon. The current warm period out paces the MWP and has increased to temperatures exceeding the warmth 1000 years ago [10]. The fact climate has changed does not tell me, or the voters, why it has changed. Only that is has done so. There is no reason to believe the drivers can change (it is arguable that the sun, PDO or AMO, and greenhouse gases) could have caused different warmings. There is a large amount of evidence that CO2 causes the current warming, and even played a significant role in the past. 4. The sun My opponent provided no substance in his argument. He says sunspots influence warming—I agree. But the sun has not been proven to affect the current warm period. My opponent merely asserts that it does. Until he gives evidence for this point, it is not significant. All he shows is a graph of past climates, not solar irradiance, cosmic ray counts, etc. Solar irradiance reconstructions show the forcing of greenhouse gases is much stronger than the sun [11]. The Stanford Solar Center has shown that the sun’s intensity has actually slightly lowered since the 60s, and the sunspots show little change. Whereas the temperature has increased [12]. CONCLUSION My opponent has failed to demonstrate a link between solar activity and temperature for the modern era and has also failed to decouple CO2 and temperature. His lag theory has been refuted, and the fact that the CO2 increase is mostly anthropogenic is something skeptics even agree on. Past climate, too, seems to prove AGW and does not refute the presumption that humans cause the current warm period. 1. http://tinyurl.com...; 2. http://tinyurl.com...; 3. http://tinyurl.com...; 4. http://tinyurl.com...; 5. http://tinyurl.com... 6. http://tinyurl.com...; 7. http://tinyurl.com...; 8. http://tinyurl.com...; 9. http://tinyurl.com...; 10. http://tinyurl.com...; 11. http://tinyurl.com...; 12. http://tinyurl.com...;