Tim Barnett, a leading oceanographer who just retired from Scripps Institution of Oceanography, this Monday gave a talk called Future Climate of Earth: A Sneak Preview [PDF] to a convention of fire ecologists in San Diego.

Barnett began by saying that he had seven grandkids, and he didn’t like to think about the world they were going to inherit from us. He then went on to succinctly explain why we know global warming is human-caused.

Most of the warming in the earth is stored in the oceans (84 percent), Barnett said, and we have exact measurements of that warming from millions of observations collected at various depths by over 3,000 buoys in oceans around the world over the last 50 years.

Because global temps have begun to soar in recent years, even as solar radiation has varied little, the sun can be eliminated as a cause, as can volcanic activity, he said.

And in a chart he presented, which tracked observations of warming in oceans around the world, he showed that natural variability does not come close to matching the observed warming, and that variability in a greenhouse-gas scenario matches well. This is one reason scientists are confident that greenhouse gases are the cause of the recent warming of the planet.

Or, as Barnett put it in his talk: “The models got it right, and in six different oceans,” each with its own warming.

But what troubles Barnett is that these models, which are already projecting major climate changes, do not consider “the physics” of two known warming factors. Neither of these planetary changes was a significant factor in the past, which is why they are not incorporated into today’s models, but both are likely to become major problems soon, if they are not already.

One is the break-up of the Greenland Ice Sheet, which James Hansen discussed [PDF] — with alarming slides — last year.

The other is the vast amount of methane, a greenhouse gas over 20 times more potent than carbon dioxide in the short run, that could be released by permafrost melting in warming Arctic regions. Barnett pointed out that in Alaska, where some roads are only passable when frozen, travel in the Arctic tundra is now down to 100 days a year or less, half of what it was just 30 years ago.

“That’s the olden times,” Barnett noted. “Thirty years ago, the olden times.” He had a number of other striking remarks:

  • Regarding a slide showing the current “business-as-usual” rise in greenhouse-gas emissions, Barnett remarked, “I don’t believe this is [as much as] the Bush plan, where you burn all the fossil fuels as fast as you can. It’s a good thing I retired last year. I couldn’t say that if I was a government employee.”
  • In response to a questioner who asked if we passed a point of no return, leading to runaway warming, Barnett said, “We’re going to take a hit. We know that. But we still have a chance to do something about it.”
  • He also said that word has gone around in climatological circles that any “reputable climatologist” willing to write a paper attacking the idea of global warming can be sure to receive $10,000.

Well, now we know what the soul of a climatologist is worth. With the world as we know it at stake, it doesn’t seem like much, does it?