The human effect on global warming is significant.

I'm not sure how well I worded the debate resolution, so I will explain further. This is a scientific debate about whether humans are driving global warming and whether it is a problem. And so as not to cause any confusion, I hereby discredit Al Gore. Any arguments that cite Al Gore as a source should be ignored. Definitions Human effect: Effect caused by unnatural human actions; this includes sources such as factories and power plants but excludes sources such as natural respiration. Global warming: The trend of rapid global temperature increase since around 1975. CO2: Carbon dioxide. AGW: Anthropogenic global warming; global warming caused by human activities. I am making the case for the existence of AGW, while my opponent is trying to prove that AGW does not exist. ======================== Contention 1: Basic Scientific Argument ======================== The sun radiates electromagnetic waves onto the earth. They pass through the atmosphere, but are absorbed by the ground. When molecules on the ground absorb the electromagnetic radiation, they then re-emit it as infrared radiation. Infrared has a longer wavelength, so some atmospheric gases, called greenhouse gases – namely water vapor, CO2, and methane (CH4) – absorb it and turn it into thermal energy (a.k.a. heat). This traps heat, causing the earth's temperature to increase. Because of the greenhouse effect, the more greenhouse gases there are, the hotter it gets. This effect isn't much like a greenhouse, but I will nonetheless use the term. For hundreds of thousands of years, CO2 levels remained in the 180 to 300 ppm (parts per million) range [1]. But as of 2007, CO2 levels were at 390 ppm [2]. The environment was relatively stable for hundreds of thousands of years, so why the sudden change? Human emissions can only be responsible. Humans have been emitting CO2 in vast quantities since the mid-70's: our cars emit it, our factories emit it, even our homes emit it. ======================== Contention 2: Scientific Consensus ======================== It is important to remember that science is not a democracy. But if nearly all scientists agree on something, it is probably correct. And nearly all scientists support AGW. I: Scientific Societies Many scientific societies have advocated for AGW. At this time, it is important to remember that scientific societies are not advocacy groups. But these societies found AGW so important that they felt they had to endorse it. The national scientific societies of 21 countries have endorsed AGW: Australia, Belgium, Brazil, Caribbean, Canada, China, France, Germany, India, Indonesia, Ireland, Italy, Japan, Malaysia, Mexico, New Zealand, Russia, South, Africa, Switzerland, United Kingdom, United States [3]. The following societies have also endorsed AGW: Network of African Science Academies, National Research Council, European Science Foundation, World Meteorological Organization, Federation of American Scientists, American Meteorological Society, American Association for the Advancement of Science [4]. This is far from a complete list, but is meant to give an idea of how many scientists support AGW. This list represents hundreds of thousands of scientists. II: Peer-Reviewed Papers Perhaps more important than the endorsement of scientific societies is peer-reviewed papers. In 2004, Science magazine conducted a search for scientific papers on the topic of global warming [5]. They searched through all papers with the keywords "climate change", for a total of 928 scientific articles. Here is a quote from [5]: {quote} The 928 papers were divided into six categories... Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position. Admittedly, authors evaluating impacts, developing methods, or studying paleoclimatic change might believe that current climate change is natural. However, none of these papers argued that point. This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies. Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect. The scientific consensus might, of course, be wrong. If the history of science teaches anything, it is humility, and no one can be faulted for failing to act on what is not known. But our grandchildren will surely blame us if they find that we understood the reality of anthropogenic climate change and failed to do anything about it. Many details about climate interactions are not well understood, and there are ample grounds for continued research to provide a better basis for understanding climate dynamics. The question of what to do about climate change is also still open. But there is a scientific consensus on the reality of AGW. Climate scientists have repeatedly tried to make this clear. It is time for the rest of us to listen. {/quote} ======================== Contention 3: Risk Management ======================== Let's assume that it is equally likely that global warming is man-made and that it is natural. In these circumstances, what are the worst-case scenarios? We assume that global warming is man-made, when it is actually natural. Worst-case scenario, our futile efforts cause an economic crash and we go into another great depression. Now let's say we assume that global warming is natural, when it is actually man-made. The benefit here is that we don't spend any time worrying about how we're all going to die. The bad news is, the human race is in a complete wreck. Expensive natural disasters have destroyed the economy. Millions are homeless and jobless, and thousands are dead. Not so good. So when these two cases are equally likely, it is far riskier to assume that global warming is natural. Actually, it's arguable that the economic crash caused by a shift in energy sources was actually inevitable, and even lessened. If we are forced to drive efficient cars and use renewable energy sources, it will be harmful to some big energy companies. But we would have run out of fossil fuels eventually. When we run out of fossil fuels, it will be heavily devastating. But if we make the shift now, because of global warming, we can make it slow enough so that big corporations have time to adapt. Additionally, "green" technologies are looking to be a sound investment. Developing them may fuel the economy more effectively than many current technologies. Assuming that global warming is man-made, far from ruining the economy, may actually help it. Even if we were 90% certain that global warming is natural, we should still take precautionary steps to prevent global warming. Even if the chance of mass destruction is only 10%, it's still 10%. We'd be playing Russian Roulette with the planet. And Russian Roulette never ends well. *** I thank my soon-to-be opponent and look forward to a fun debate. *** References [1] http://www.newscientist.com... [2] http://www.newscientist.com... [3] http://logicalscience.com... [4] http://www.aaas.org... [5] http://www.sciencemag.org...