Actually when you apply statistical methods to raw temperature data over time in relation to CO2 levels, there is no scientific or statistical evidence whatsoever that increased CO2 from man causes an increase in global temperature. It is not a question of "denying" it is a question of presenting proper and un-adjusted scientific facts and figures. The only the Climate Alarmists have done is undermine scientific integrity to drive a political agenda - which as someone with a STEM background I have such an issue with these people.,
Murry Salby, author of a widely adopted text on atmospheric physics, was the first, I think, to point out that while CO2 is highly correlated with temperature, the correct relationship is the opposite of that assumed by Hansen in setting forth his anthropomorphic CO2 hypothesis in the early 1980s. The time resolution of the earliest data was insufficient to determine what was the dependent variable. This was later remedied by others. According to Salby's work, Temperature is the independent variable and CO2 the dependent. Several studies by other experts published since have confirmed this. Salby deserves a lot of credit for being one of the first to show that temperature is the independent variable. He did it at a time when most scientists were on board with the Hansen hypothesis. Also, physicist Ferenc Miskolczi's paper, a paper stemming from his theoretical work at GISS, if it is correct, calls into question the assumption that feedback from rising temperature is positive, as assumed by all models so far. Miskolczi used a novel energy balance approach and concluded the feedback must be negative. GISS management attempted to suppress publication of his seminal paper. Because of this, he left GISS, and eventually was able to publish. He has published one or two follow-up papers. As the half life of CO2 in the atmosphere was unknown at the time models began to be used to predict catastrophic warming, a value for half-life had to be guessed. This is a key parameter in the models. Twenty years later someone pointed out that the half life could be accurately computed from decay of the atmospheric C-14 CO2 spike caused by 1950's atmospheric nuclear weapons testing. The actual half life of CO2 is approximately an order of magnitude less than what was initially assumed. Current models of course make use of the accurate half-life and predict, therefore, lower amounts of warming. Some of the early models failed to account for vertical convective cooling, which is probably the single most important mechanism for atmospheric cooling.To this day no one has yet figured out how to accurately model the contribution of clouds. Some scientists are of the opinion that the ice core data is not supportive of CO2 driving temperature. Much of the early work using proxies for temperature (tree rings etc.) that Hansen relied on has been shown to be unreliable. The 2014, Bulletin of the American Meteorology Society Survey of atmospheric physicists and meteorologists working and publishing in the area of global warming and climate studies, shows that opinions re the importance of anthropomorphic CO2 to warming are all over the map. Currently, despite popular media hype, there is no consensus among experts, and if anything, support for Hansen's hypothesis among experts is weakening. What is very odd is that there is a clear consensus that global warming is being caused by Anthropomorphic CO2 among everyone except the experts! Something is obviously amiss. Can it be that millions spent to support climate studies and anticipated profits from trading in Carbon Credits is somehow clouding our judgement?