well there's a big difference between not surviving several hundred years of history and being purposely deleted after a FOIA request. AGW is not a fundamental explanation of the workings of the universe, its the conjecture of the result of adding CO2 to the atmosphere and trying to anticipate the results. The question isn't whether CO2 is a greenhouse gas, that's scientific fact that has underpinings that can be readily tested experimentally. We know that CO2 absorbs IR light, it can be tested. AGW is an outgrowth of the effect that has to be modelled and inferred from past data, which isn't just a graph of past temperature and CO2 levels. One point of contention in the e-mails is that prior to ~1900 temperature is inferred from tree ring growth, until 1960 the tree rings and the temperature record matched, after 1960 the tree rings and temperature record began to diverge, in the graphs, the pre-1960 tree ring inferred record was grafted onto the post-1960 temperature record, and there are differing views on why there is a divergence. (pollution, non-linear temperature/growth relation are cited as possibilities). But at the end of the day, there's no way to do a controlled experiment, and they the models they have had in the past that suggest AGW have not predicted the present conditions, so though the best we can ever hope for is a model that cannot be tested fast enough in order to give us time to act on its conclusions. Its not as cut and dry as gravity, its how an extremely complicated, non-linear feedback system(the models do not cover this, scientists say its a secondary effect) whose operation varies with time (aka a 1ppm increase in CO2 has a different impact depending on not just the current state, but past states). That's why Ph.D's work on these things, you're trying to draw a conclusion from a situation where normal experiment cannot apply.