Resolved: Climate change is, on balance, anthropogenic in origin

In R1 global warming was defined as an average increase in temperature since the late 19th century. We have caused pretty much all of the warming since 1976 and a significant percent of the pre-1940 warming, with a cooling spell between the late 40s to early 70s because of human aerosol emissions and a decline in TSI. King’s entire argument is… paleoclimate. But I don’t have to prove that we caused warming 500 million years ago, only since around 1870 or so. Paleoclimatology does have an application in this debate: whether or not CO2 causes (or doesn’t cause) past climate changes is important. It can prove whether or not CO2 has any influence on the climate. My opponent’s conclusion — that I have to prove changes before the industrial revolution — breaks rule 6, and warrants an automatic merit loss. I will refute the case anyway, but only the relevant details: A) Phanerozoic temperature record King shows us a graph plotting temperature and CO2 throughout the phanerozoic eon, and tells us that there is no correlation. For at least the last few thousand years, CO2 has had a strong impact on climate [1]. Unfortunately,King’s graph uses a study which I preempted. It must be noted that the graph my opponent uses does not show the error bars, so any correlation (or non correlation) is uncertain at best. And, as I argued last round, the man who made the graph (GEOCARB; Berner 2001) actually says that there exists a long term correlation between temperature and carbon dioxide [2]. Berner’s study also fails to take into account saturation effects. When this is accounted for, the correlation between CO2 and temperature is almost perfect [3]. So, the second graph my opponent uses is blatantly incorrect. Not only do the authors of the data say that I am correct, not only do the error bars tell us that the results are not really with my opponent, but a separate analysis *improving* the methodology finds a nearly *perfect* correlation between CO2 and temperature. B) More recent temperature changes The graph my opponent uses seems like a sketchy-tabloid esque graph. There is no reason to trust it. The data is not so cut and dry, especially because data exists showing that temperatures are warmer — not cooler — than temperatures within the past 1000 years [4]. And the timescale king uses is cherry picked. Using the past 65 million years, CO2 is the predominant climate forcing of temperature changes [5]. Research focusing on the past few interglacials — which includes king’s graph — has concluded that CO2 “plays . . . a key role in amplifying the initial orbital forcing.” [6] Plus, the graph king uses does not take into account other forcings. Of course other factors exist in climate — I am not arguing that CO2 is the only one, only that is can be (and is) a forcing since about 1870. Climate changes in response to whatever forcing exists at that date and time. And today, CO2 is driving climate. Just like how short term (volcanoes) and long-term (GCR fluctuations) can all affect climate, CO2 has *always* played *some* role in climate. On some timescales, it is dominant [3][4]. Merely because climate has changed for other reasons does not mean that humans have no effect. Most of the time, it is not a gun which kills a person, but it would be wrong to conclude that guns do not kill. Just because climate has changed before does not necessarily mean that our change is natural. C) Humans have only existed for 200,000 years So? 1. https://www.skepticalscience.com... 2. http://earth.geology.yale.edu... 3. http://www.sciencedirect.com... 4. http://www.meteo.psu.edu... 5. http://droyer.web.wesleyan.edu... 6. http://icebubbles.ucsd.edu...