Man-Made global warming exists* and poses a serious threat to humanity.

Con's case:Premise 1: Global Warming PotentialWhat few people realize about things like Green House Gas is that they are not all born equal. For example, Carbon Dioxide has a Global Warming Potential of 1. Global Warming Potential is the total effect a single amount of gas has on Global Warming. The list is has follows: (1)Carbon Dioxide -- 1Methane -- 21Nitrous Oxide -- 298-310CFC's -- VariousWater Vapor -- 0.25With this in mind, we move on.1) http://cdiac.ornl.gov...Argument I: The Effects of Man-Made Carbon Dioxide.Human's release approximately 35 gigatons of Carbon Dioxide into the atmosphere each year (2). Only 4.3% of the 812 gigatons released total every year. Even at only 4.3% of total CO2 emmissions, our effect over it, is mild at most. Carbon Dioxide is very weak, as opposed to common census, having only a Global Warming Potential of 1.In total, Carbon Dioxide makes up a grand total of 3.618% of the total Gas House Effect (3). Water vapor makes up 95% of the total Greenhouse Effect. Carbon Dioxide's number increased from 295 ppm to 400 ppm, an increase of 105 ppm. 1 Gigaton of CO2 is worth 2.13 ppm (4), so an increase of 105 ppm would equal 49.29 gigatons. Since 1 gigaton of CO2 is worth 0.004% of total Greenhouse Effect, 49.29 gigatons is worth an additional 0.21% to the Greenhouse Effect, a total temperature increase of 0.15°F. That means we are responsible for 10% of total increased warming.Assuming human's did in fact raise the amount of CO2 by 105 ppm, the effect on the climate would be measly. Temperatures would raise only 0.28% since then. People gravely exaggerate to effect of CO2 on the climate. It is the second weakest Greenhouse Gas in the world behind Water Vapor. GAS -- GREENHOUSE EFFECT -- HUMAN EFFECTWater Vapor ------ 95.000% -- 0.001%Carbon Dioxide -- 3.618% ---- 0.117%Methane ------------ 0.360 ------ 0.066%Nitrous oxide ----- 0.950% ---- 0.047%Misc ------------------- 0.072% ---- 0.047%Total ------------------ 100% ------- 0.278% Assuming the increase in the other gases ppm were the same proportionately, we would be responsible for an increase of nearly 0.20°F. This leaves 1.33°F left that human's are not responsible for.Many people would claim we've caused temperatures to raise enough to evaporate enough water to make up the difference. This would be entirely irrational. At an increase of 0.20°F, water wouldn't evaporate much more than it was prior. Thats less of a difference in tempature shift than what we'd see from one minute to the next. The argument assumes 0.20°F can heat up the ocean enough to make up such a wide difference. Such an increase from only 0.20°F would mean that the ocean would be boiling in the summer (temperatures of 90°F and up, an increase of 31.88°F from normal temperature). It's a weak and unsustainable excuse. Even at 1.53°F, it's not likely.2) http://volcanoes.usgs.gov...3) http://www.geocraft.com...4) http://cdiac.ornl.gov...Argument II: Argument From Nature:Is it entirely possible for nature to be responsible? Of course. Nature has seen worse times then now. CO2 ppm is at 400 right now, but in the Mesozoic period, long before man, it reached 2000-4000 ppm.(5) 7000 ppm in the Cambrian Period. This implies that people aren't needed for absolutely unbelievable increases in ppm. It's entirely possible for nature to do this on it's own. Another issue this brings up is that, at 7000 ppm, 6705 ppm larger than in 1900 (63.8% larger than the 105 ppm increase) the temperatures were 10ºc higher then than today. Proportionately, temperatures should have been 54.23ºc higher then than today. This empathizes high little of an impact CO2 has on the global temperature.So what in nature right now could be causing such in increase in temperature? A basic cycle.5) http://droyer.web.wesleyan.edu...(GCA).pdfArgument III: The Global Warming Cycle:Global Warming activists love mentioning how temperatures are higher now than they were in Human History, forgetting how Human History is only 10,000 years old at most. In the chart above, we see that past warming periods. Take into account that the temperature of today is now above anything on that list, and then look at the past 400,000 years. According to the data, the World has been heating and cooling rapidly for 100's of thousands of years, back past a few million, even. It has been the world's cycle. CO2 ppm has been following along. Right now it's where it should be increasing. CO2 has been raising in recent history (15,000 years) and it's merely continuing to, with or without humans. Temperatures, as well, have been randomly going up and down in the past 15,000 years. Long before industrialization. Of course temperatures are up... We're in the warming cycle. We are actually in the coldest warming cycle in the past 400,000 years, the fact that it isn't warmer is amazing. To assume human's are responsible is more Post Hoc then anything else. Temperatures SHOULD be increasing right now. It's only natural.CO2 is so unimportant, that despite a rapid increase around the 9,000 year period, temperatures have decreased more than increased, and quite on it's own accord.Conclusion:Human's are responsible for very little of the Green House Effect. Our biggest contribution is CO2, which (and my opponent will probably stick to CO2 as his weapon) is very uninfluencial in the overall scheme of things. The increase in CO2 has been going on steadily since over 9,000 years ago. It's nothing new.There is nothing unique about this warming period other than how cold it is. Human's contribution to Global Warming is minuscule, and isn't a threat to human life. Global Warming might be a risk, at most, in time, while not likely... But Man-Made Global Warming is not.