The n-Category Café

What will come first? A good understanding of n-categories, or ecological disaster unravelling the world’s economy, thereby removing support for research in mathematics. Better prepare the mathematical seed bank.

John has more on this in his diary I see:

• John Baez, Diary: October 7, 2006.

He mentions positive and negative feedback mechanisms. Another negative feedback is this: When there is more CO₂, trees can grow in drier areas because they don’t have to keep their pores open as much to get a given amount of CO₂. So they lose less moisture. There has to be some feedback that has kept the CO₂ level very steady before the recent rise, and this is a likely candidate. One big question is whether or not we’ve pushed the climate so far from equilibrium that it can’t roll back to where it was whatever we do.

Here is Stewart Brand’s summary of my talk:

The graphs we see these days, John Baez began, all look vertical — carbon burning shooting up, CO₂ in the air shooting up, global temperature shooting up, and population still shooting up. How can we understand what really going on? “It’s like trying to understand geology while you’re hanging by your fingernails on a cliff, scared to death. You think all geology is vertical.”

So, zoom out for some perspective. An Earth temperature graph for the last 18,000 years shows that we’ve built a false sense of security from 10,000 years of unusually stable climate. Even so, a “little dent” in the graph of a drop of only 1 degree Celsius put Europe in a what’s called “the little ice age” from 1555 to 1850. It ended just when industrial activity took off, which raises the question whether it was us that ended it.

Nobel laureate atmospheric scientist Paul Crutzen suggests that the current geological era should be called the “Anthropocene,” because it is increasingly dominated by human-caused effects. Baez noted that oil companies now can send their tankers through a Northwest Passage that they may have created, since it is fossil fuel burning that raised the CO₂ that raised the summer temperatures in the Arctic that melts the polar ice away from the land.

Zoom out further still to the last 65 million years. The temperature graph show several major features. One is the rapid (every 100,000 years) wide swings of major ice ages. When they began, 1.35 million years ago, is when humans mastered fire. But almost all of the period was much warmer than now, with ferns growing in Antarctica. “Now it’s cold. What’s wrong with a little warming?” Baez asked.

The problem is that the current warming is happening too fast. Studies of 1,500 species in Europe show that their ranges are moving north at 6 kilometers a decade, but the climate zones are moving north at 40 kilometers a decade, faster than they can keep up. The global temperature is now the hottest it’s been in 120,000 years. One degree Celsius more and it will be the hottest since 1.35 million years ago, before the ice ages. Baez suggested that the Anthropocene may be characterized mainly by species such as cockroaches and raccoons who accommodate well to humans. Coyotes are now turning up in Manhattan and Los Angeles. There are expectations that we could lose one-third of all species by mid-century, from climate change and other human causes.

Okay, to think about major extinctions, zoom out again. Over the last 550 million years there have been over a dozen mass extinctions, the worst being the Permian-Triassic extinction 250 million years ago, when over half of all life disappeared. The cause is still uncertain, but one candidate is the methane clathrates (“methane ice”) on the ocean floor. Since methane is a far worse greenhouse gas than carbon dioxide, massive “burps” of the gas could have led to sudden drastic global heating and thus the huge die-off of species. Naturally the methane clathrates are being studied as an industrial fuel for when the oil runs out in this century, “which could make our effect on global warming 10,000 times worse,” Baez noted.

“Zooming out in time is how I calm myself down after reading the newspapers,” Baez concluded. “A mass extinction is a sad thing, but life does bounce back, and it gets more interesting each time. We probably won’t kill off all life on Earth. But even if we do, there are a hundred billion stars in our galaxy, and ten billion galaxies in the observable universe.”

Stewart Brand

Kevin Kelly of the Long Now Foundation wrote:

… the lesson I took from your talk was the under-appreciated title – Zooming. The ability and need to think in MULTIPLE time scales and zoom between them is what is so often missing. Now that I’ve seen climate in zoom mode, I want to see biology in zoom mode, architecture in zoom mode, technology in zoom mode, and so on.

I’d love to see that too!