Dinosaur Farts

The House of Representatives has recently held hearings on the IPCC AR4 report on climate change. Rep. Dana Rohrabacher (R-CA), pictured left, had this to add to the discussion:

So, whether or not how dramatic this change will be, or is, what it’s caused by, are things that honest people, I think, can disagree with, and I really personally, having been a journalist, the first thing I was always cautioned by when someone was claiming, well, everybody is on my side, or everybody says this, or there is a total consensus, almost always when people said that to me over my years as a journalist, it wasn’t true. It was that there were honest people who disagreed and significant disagreement on such issues.

Of course honest people can disagree. That's what makes science work. But it does raise a red flag when pretty much all the scientific bodies come down on one side of the issue and pretty much all of the relevant peer reviewed literature does as well. Nothing is 100% certain in science, of course. But that doesn't mean that everyone's honest opinion should be given equal weight when it comes to policy decisions.

His website on global warming has much the same to say on the topic. Right at the top of his page, Dana Rohrabacher claims, as Sen. James Inhofe did not too long ago, that 17,000 scientists signed the Oregon Petition, despite the fact that being a scientist wasn't a requirement for signing the petition, there was poor oversight as to who actually signed, and that the petition was circulated in a rather shady fashion.

Dana also provides several other links to various petitions and think-tank websites to demonstrate that there is a "significant disagreement" regarding climate change. However, all of these petitions and think-tanks seem to recycle the same names under different organizations to create the appearance of a large group of people. For example, Fred Singer is involved with pretty much every link on that page. He signed the Oregon Petition, he founded the Science and Environmental Policy Project, he is one of the experts at the National Center For Policy Analysis Global Warming Hotline, he is one of the 60 signers of the Canada petition, he is one of the signers of the Statement By Atmospheric Scientists On Greenhouse Warming, and he was a member of the Center For Science and Public Policy (Frontiers of Freedom). Some other recycled names include: Sallie Baliunas, Patrick Michaels, David Legates, Frederick Seitz, Willie Soon, Stephen McIntyre, and Ross McKitrick. Repeating these names over and over doesn't increase the number of "honest people" who significantly disagree over the issue.

Anyway, Dana went on:

We don’t know what those other cycles were caused by in the past. Could be dinosaur flatulence, you know, or who knows?

Yes, there have been temperature cycles in the past, but the temperature has generally been very slow to warm. As far as dinosaur farts go, NASA scientists Schmidt and Shindell have published research indicating that during the Paleocene-Eocene Thermal Maximum (a warming period 55 million years ago), a massive release of methane (a greenhouse gas) from the ocean floor resulted in a "rapid and intense warming" (abstract here, news release here).

Rep. Rohrabacher also suggests that since we don't know what caused climate changes from millions of years ago, we probably don't know what is causing the climate changes today. That doesn't logically follow at all, and doesn't diminish the fact that we have good proxy data from the past 1,000 years and direct observations for the past 150 years. This is what they show:


The temperature graph correlates pretty well with this graph showing a rise in Carbon Dioxide emissions into the atmosphere from the same time when the temperature spiked upward:


You can also see that the carbon dioxide concentrations in the atmosphere have been somewhat anomalous within the past 400,000 years: