global warming is significantly man man made

My opponent, again, mostly points to a link... I suppose I have to debate a blog. The website makes these claims1) CO2 causes warming through the greenhouse effect2) CO2 correlates with temperature3) Therefore, CO2 causes global warmingI will refute these in order1) CO2 causes warming via the greenhouse effect No one denies that CO2 has *some* effect on the climate. In fact, in a no feedback scenario, a doubling of CO2 causes 1.2 degrees C in warming. This means that, at most, CO2 has caused about half--about 40%--of the recent warming. That warming caused by CO2 would likely have beneficial impacts on earth, and would be no cause for alarm. Therefore, it should not be deemed 'significant'. The way alarmists construe global warming is that the heat caused by CO2 will cause a runaway greenhouse effect via positive feedbacks. This leads to estimates that a doubling of CO2 causes in excess of 3 degrees C of warming. This would make CO2 the main cause of global warming, and therefore 'significant'. However, there is no good reason to assume these feedbacks are positive. If they are negative, the effect of CO2 on climate would drop significantly--and reduce the alarmist argument to nothing. The reason alarmists see positive feedbacks is due to climate models--in fact, the entire theory of positive feedbacks is based on these estimates. They can only reproduce the warming from 1970 - 2000 if they include strong positive feedbacks. If they fail to add these in, they cannot reproduce these temperatures. Therefore, alarmists claim, feedbacks are positive. But this begs the question: are models reliable? Do they capture all the natural processes? The answer to these questions is an astounding no. In fact, if you properly include these processes, we see that CO2 is mainly trivial to climate change: other natural factors better explain the recent warming. Research has found that clouds, about 40% of them, contain rain or drizzle and this drastically affects the radiative properties of clouds. Models do not account for this phenomena. It is likely that once all of the other factors are included, the need for positive feedbacks would disappear. These models fail to account for many negative feedbacks, and the new emerging idea that the cloud feedback is negative, not positive. They dont include all the solar variables, they either don't have or misrepresent oceanic cycles, etc. The fact is, models--and therefore, positive feedback theory--is severely lacking [1. Our Climate, iOS app]. In fact, recent papers have come out proving that climate sensitivity is much lower than needed to demonstrate that CO2 is a significant driver in climate change. When the El Nino effect is properly accounted for, sensitivity falls significantly--from 2-3 degrees C as alarmists claim to 1.3 degrees C, a no feedback climate system [2. http://www.drroyspencer.com...]. Studies looking into the cloud feedback--arguably the most important positive feedback--has found that, contrary to what alarmists claim, the feedback is negative, and this makes the CO2 contribution to warming much lower than it was previously estimated [3. http://www.drroyspencer.com...]. The fact is, feedbacks are likely negative, not positive. This refutes my opponents entire contention that CO2 can even cause significant warming in a real climate system (labratory studies cannot account for feedbacks). 2) CO2 correlates with temperature Wait, what? If this is true, how to alarmists account for the 1970s cooling (I know how they explain it--I will refute it if she brings it up), the 1997 pause in temperatures, and the fact is has been cooling s ince 2001? In fact, over the last 500 million years, CO2 has no correlation with temperature. In fact, there have been periods of time where the CO2 parts per million exceed the thousands (it is around 400 today), and there was an ice age on earth. To me, that doesn't look like a good correlation [4. http://www.paulmacrae.com...]. Over the same 500 million years, galactic cosmic rays--a forcing as well as a proxy for solar changes--correlates perfectly with temperatures. GCR's explain a huge part of the warming over that time period. This means cosmic rays and other fluctuations in the suns power are much better correlated with temperature, not CO2 [5. http://stephenschneider.stanford.edu...]. 3) CO2 causes significant warming I am confident that, at this point in the research, this cannot be said with confidence. I conceded? No, I didn't. I actually disagreed with the 1/3 remark--arguing that, instead, the sun causes 60% of the recent warming. However, what I argued is that if this is true--that solar forcings do cause 1/3 of the warming--AGW is false. The models were not able to accuratley even give the sun 1/3, meaning they cannot account for basic TSI variables. If they cannot account for this basic phenomena, the entire theory goes up in flames. My opponent attempts to make the claim a consensus is against a solar forcing. Science isn't done by consensus. And in fact I have not seen a meta-study on solar forces. Therefore, to claim there is a consensus against solar influence, my opponent must prove this. In 2013 alone, 71 papers showed a strong solar effect. In a comprehensive list, there are hundreds of studies showing a strong solar impact [6. http://chrono.qub.ac.uk...].