The entrance to the meeting space is a wide set of stairs and escalators. When it's full of people I feel like a drop in a stream tumbling down rapids. The bottom is a roiling mass of humanity meeting, greeting, sitting on benches, or threading their way toward various rooms.
I went to a session about how we detect climate change in our data and how we decide what's the cause. The speakers all work with elaborate computer models, and their talks went deep into the subtleties of working with imperfect data and numerical shortcuts.
Still, several speakers made a point of mentioning their hunches. Sydney Levitus of NOAA reported on his group's modeling ocean temperature over the last half-century. They run world weather data through their equations time after time, varying one thing after another to explore the uncertainty space, the wiggle room in the numbers. "Our results are growing consistent—within 50 percent," he said. He believes that ocean warming is probably due to human releases of greenhouse gases.
Other speakers assessed factors including volcanoes, El Niño and solar fluctuations, subtracting them from the record to see what is left. They presented evidence from tree-ring records, oxygen isotopes, the temperature in underground boreholes. Nearly all agreed that the signs of a human effect on climate are strong. Thomas Crowley of Texas A&M put it most plainly: "It looks like a duck, walks like a duck, and quacks like a duck. Maybe it quacks with a quirk, for instance with the intermediate-depth ocean waters and some other things. But it's more like a duck than a pig!"
At midday I wandered through the huge hall full of posters. Long rows of partitions have poster presentations on them, each marked with the times that the author is there to discuss it.
The afternoon session I chose was about environmental evidence of the natural disasters that struck ancient human societies. One example was sediment records from Lake Titicaca high in Bolivia, showing how the lake level's changes matched archaeological evidence of prosperity and decline. I was impressed when Richardson Gill, author of "Great Maya Droughts," stood with no slides or overheads and told of the century-long drought in the ninth century that killed some 90 percent of the Mayan people. That strong climate shift involved extreme cold in Europe too—for instance, the Nile River froze over in the year 829. He explained that large volcanic eruptions also created temporary cold periods, causing famines among the Maya, during the historical period.
It seems that this session interleaved scientist-authors with the usual kind of scientists, who present detailed studies of this site or that. It was a treat to see Bill Ryan, of "Noah's Flood" fame, argue that the Minoan civilization in the 18th century BCE collapsed due to a giant volcanic eruption. The Minoans of Crete were not killed directly by the volcano, he said, but by political/military disruptions stemming from a cold period caused by the eruption—a domino effect involving the collapse of the Hittites, Babylonia and Egypt destabilized Crete two generations later.
And Jared Diamond, author of the classic "Guns, Germs and Steel," recounted stories of societies that collapsed when their habitat was destroyed. The people of Easter Island, for example, cut their forests for lumber to build fishing boats and erect their mysterious statues. When the trees were gone, they could no longer fish, "and the only remaining large meat animal was humans." A century later Easter Island was a thinly populated place of complete savagery.
Diamond's theme was that climate change preys on weakened, ecologically unstable societies. A questioner pointed out that today we have the benefit of history plus geologic data, such as the long climatic time series we've compiled. He replied, "That's very true. Whether our grandchildren in 2050 can live the same life that we do today depends on what we can learn from the time series that you are building." That remark seemed to put everything I heard—the abstruse research of the morning session and the story-telling of the afternoon—into sobering perspective.
Afterward at the press reception, I sipped wine and conversed with my peers. You see their stories in your newspaper and your science magazines, maybe even on the radio and TV. But I still felt the weight of Diamond's words. It's one of the reasons I maintain this site, and why science reporters do their work.
