Danlib1,
You are confused, making a simple category mistake. The relevant distinction is not between theory and fact, but between truth evaluable a proposition and a policy. Eugenics is a policy, like integration and space exploration. Global warming is a proposition: that the Earth is warming at a potentially dangerous rate due to human caused factors like dramatically increased carbon emissions. That claim may be true or false. Eugeneics is neither true nor false; it is either going on or not.
There is no theory/fact dichotomy. It may be your theories that there are three beers in your fridge and Oswald acted alone. Either may be true, either may be false. If they are true, they are facts, despite being theories. Einstein's special relativity theory is a theory, which may be true, and state facts. The theory of evolution is also a theory, and damn near every working biological scientist holds it. "Creationism" is also a theory, which almost no biologists respected outside of religious communitiies accepts. They are both theories. At most one states a fact. But it is no criticism of a claim to call it a theory, since even the best, most confirmed, useful, universally accepted theories are still theories --which may or may not be facts.
Global warming is either a fact or not, but it is a very widely held theory by independent and unbiased -- i.e., not in oil companies pockets-- scientists. But it is certainly a theory. Eugenics is noit a theory or a fact, and it is not anymore much practiced by humans on humans.
Zilla-- I am no expert on whether Glogal warming is actually occuring and alarming and all that. Indeed, I've been skeptical for a long time. But the evidence based on deep core ice samples from Antarctica Gore presents in the first half hour of his documentary is pretty compelling, going back way longer than the whole series of relative local coolings and warmings that have occurred since Homo Sapiens first appeared. If his evidence is at all good, whether or not we are causing these changes, we have never been around for anything like them. It has been consistent through all of this time that those making profits never accepted claims that they were doing so at the cost of the general good.
The resonance"deniers" makes with holocaust discourse is not unintentional; the cases are not identical, but that doesn't mean the resonances shouldn't be pointed up. Al Goreis no socialist(at least not in any sense in which a vast majority of Americans are not). And "socialist" is no epithetor anything like a univocal "cause". It represents a wide range of policy options recognizing the fact that private ownership of the means of productiion is not in all cases conducive to the public weal or justice. Free market uber alles is an unsubtle "doctrine", dead everywhere, and understandably, its advocates are defensive.