It is very difficult to, with any certainty, say what the actual cause is.
However, there has been no reduction in CO2. And yet Phil Jones himself has said no warming since 1995. Further he is willing to admit that the Medieval Warm Period (MWP) was warmer than the current temperatures. In addition that the planet has been cooling since 2002.
On the basis of that is it not reasonable to presume that man is not the prime component of the current cycle of warming. With the MWP being warmer it would seem clear that man could not have caused that.

More study is needed, FROM ALL SIDE, on the subject. No research or study should be tossed aside just because some people do not like it.

As far as the "consensus", again from Phil Jones, the only consensus in the field is that there is no consensus.

Quote Originally Posted by leo9 View Post
OK, let's go further back and try to start from basics.

A) CO2 is a greenhouse gas, one that absorbs infra-red, thus increasing the net heating of the atmosphere for the same level of insolation. There are other significant greenhouse gasses - methane for one, hence the concern over the rapidly increasing release of methane from warming permafrosts - but CO2 is the one whose level is the most directly affected by human activity.

B) Since the Industrial Revolution began the large scale burning of fossil fuels, the percentage of CO2 in the atmosphere has risen ever more rapidly.

C) The world's climate, and specifically the world's temperature, varies according to a number of cyclical patterns. The net influence of these cycles has been being studied for a hundred years or so and is pretty well understood, and the theory agrees with observation beautifully - up to the last few decades, when the curve went off in entirely the wrong direction. According to the theories that all climatologists were happy with until AGW came into the picture, the world should be gently cooling down (hence the 1970s scare about a "new Ice Age".) Instead it is warming ever faster.

Now my first question is, which of these propositions don't you believe? If (A), you can borrow space in any High School science lab for an afternoon and test it yourself. If (B), note that this is not just one researcher or group of researchers' opinion. The chemistry of the atmosphere is available for anyone to study, and people have been doing quantitative analyses of it since the 19th Century; the results are not hidden or secret or held in one database open to fudging.

I note that you don't dispute that the warming is happening, so the question is the cause. If you believe that the existing theories of climate cycles are enough to account for it, then you can either take my word for it, or do the research yourself to find out, that back in the mid-20th Century, when AGW was a minority crank theory, the consensus of climatology was that no such warming could possibly happen because they knew how the cycles worked and they were on a downward phase. That is why the majority have come around so solidly: they saw results that didn't fit the established theory, so they looked for a theory that correctly predicted what actually happened. That's how science works.

The point is, if you accept the evidence but you don't accept the theory, you are left with the conclusion that something contrary to previous climatological theories is happening, and it is completely unexplained and mysterious. And since there is an explanation available for it which is simple physics, this is a bit like insisting that a pan on the stove is growing hot due to mysterious and unexplained forces, while refusing to see that the stove is heating it.