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The article in LiveScience says:
Smallpox was a vicious disease before its eradication in the 1970s, but the virus is hardy and can survive long-term storage. One such storage unit is the tundra of the high northern latitudes that preserves an unknown number of bodies that could have died from smallpox. Global warming is now rapidly thawing this freezer, increasing the chance that someone could come into contact with a smallpox-infested body, thereby reintroducing the disease.
Of course there are many people like my brother-in-law who scoff at global warming; uneducated folks pepper our nation like fleas. He wouldn't believe in anything that is connected to Al Gore. Such is life in America.