Discounting time in aircraft, what person has spent more time above the altitude of 18,000 feet than anyone else in human history?

The answer is widely believed to be Ohio State University glaciologist Lonnie Thompson. (He's also, incidentally, surely the only glaciologist ever featured in an ad during college football's BCS championship game, which he was last year.) Along with his wife Ellen, Thompson has made a career out of drilling for data-rich ice-core samples in tropical glaciers--and to find glaciers in the tropics, you have to get up pretty high. Now, though, as the AP's Charles Hanley reports, the Thompsons are in a race against time. As the planet warms, tropical glaciers are melting fast--Kilimanjaro's are likely to be gone within a decade, at most--so they're trying to visit the remaining unexplored tropical glaciers and extract samples before the glaciers disappear. Their next stop is New Guinea's remote Puncak Jaya, where ice-core samples could hold clues about the relationship between global climate conditions and everybody's favorite meterological phenomenon, El Ni