I've said before that most so-called conspiracies can be more readily explained by simple human stupidity. Take, for example, the recent brouhaha over NASA's Goddard Institute for Space Studies, whose climate data for October reported temperatures to be an astonishing three-quarters of a degree above normal. It turns out the data was badly skewed because in several cases September's data had been used rather than October's.
Some of the commentary I've read accuses the GISS of deliberately putting out a false report, but I see no need to propose a more complicated explanation when a simple one will do: The GISS was expecting to see warming, so they didn't question the data. This is why scientific experiments are double-blind whenever possible. In lieu of that, it might be wise to have your enemies proofread your work: those on the other side of the global warming debate found the error quickly.