For all the snark in the comments, he's right about a couple of things.
to accurately model weather / climate, you need to solve navier-stokes equations. unfortunately, there are too many variables and not enough equations, so these cannot be solved. most models simplify these equations, either by working in only one or two dimensions, or by the use of largely arbitrary parameters which have little meaning in the physical world. most commonly, there parameters are linked to CO2/ppm in the MMS, but really, they're not much more than a fudge factor. such compromises in the set up of a model lead to compromises in the legitimacy of the results from such models. weather is an incredibly complex system, and creating meaningful parameters to accurately describe a weather situation in order to model it is far from trivial.
current meteorological / climatic models struggle to replicate hurricanes / typhoons / tornadoes, for example. these are known as 'sub-grid phenomena'. even when they use historical data to try to replicate historical events, these models struggle. only a fool would use a model that fails to accurately replicate a known event to predict future, unknown events and present the results with arrogant certainty. (for clarity, scientists aren't presenting their findings with this arrogant certainty, but by the time the paper has been washed through a few 'science desks' at a few media outlets, and the results sexed up a bit, this is what makes it into the MMS.)
media reporting of climate change is woefully wooly in its language. average temperature, for example, is meaningless phrase in scientific terms. there is no agreed way to calculate it, and once you have an average of sorts its about as useful as an average telephone number. (is 10 degrees centigrade twice as hot as 5 degrees centigrade? nope).
all this just illustrates the problem of politicising science - not just dumbing it down so that the 'man on the streets' can grasp it, but dumbing it down so far that politicians can grasp it too - but then fighting elections based on poor understanding of the science. MMS drives this with their need for graphs, numbers and sensationalist headlines. science is being corrupted for the sake of making to so incredibly black and white.
the huge majority of scientists agree, to greater or lesser extents, with the thesis that climate change is happening, and man has contributed. the black and white certainty presented in the MMS does nothing to help the science advance, and gives rise to the feeling of a conspiracy theory to people like john g. it is not an accurate reflection of the actual science going on, or the variation in interpretation of the data across the scientific community.
for clarity, climate change is real. it might not be happening at quite the pace that hollywood or the UN (IPCC) would have you think, and man might not be quite as big a contributor to it as some single-issue organisations would like you to believe, but it is real. it is certainly more real than john g thinks. but the case for it, and man's involvement in it, is not as black and white as some in the snarking classes would like.
john g is just being a skeptic, and that should be applauded. ok, so he's gone a bit far and strayed into the realm of conspiracy theory, but really, questioning the validity of these models and the results they generate puts him ahead of a lot of people who have equally certain but opposite opinions on climate change.
