Astroblog

Snowball Earth, Image Credit NASA/University of Bristol.

Tim Lambert (Deltoid) debated Viscount Monckton on Friday 12 February, (Charles Darwin's Birthday). The debate can be seen here, audio here, slides here and a transcript and some discussion here, and further discussion here. The conduct of the debate shows why researchers and experts are unwilling to take part in debates with global warming “sceptics”/creationists/anti-vaccinationists. Too often the contrarian debater is an accomplished showperson who rapidly delivers a series of statements with such confidence that the audience is unaware they are talking rubbish, and the expert is left trying to decide which misrepresentation to tackle in the short time allotted them.

Such was the case in the Monckton –Lambert debate. Monckton is confident, speaks clearly and with flair (and a smattering of self depreciating jokes). It would be a rare non-expert audience member who would know that he is completely misrepresenting his material.

However, Tim was able to get in a telling point very early on. Monckton uses a paper by Pinker et al. to support his claim that climate sensitivity is low, and increased CO2 will have negligible effect on temperature and climate. Tim was able to read out a statement from the author that Monckton was wrong (in delightful irony Monckton kept on calling the lead author male, but she is female), and had made a fundamental mistake in his calculations.

Monckton recovered quickly, and spun a delightful story to reinforce his claim that climate sensitivity was low using an Australian setting. There are two places in Australia where the Curly Mallee grows, these are on outcrops of cap carbonates laid down around 750 million years ago*. Monckton claimed the cap carbonates showed that the atmosphere contained around 300,000 ppm CO2 (compared to the roughly 387 ppm CO2 at present, though he might have meant 30,000 ppm, it’s hard to tell from the recording) during a major glaciation, and implied that the CO2 levels could not be consistent with the climate sensitivity everyone else calculates.

He couldn’t be more wrong.

He’s talking about Neoproterozoic Snowball Earth!

Neo-klatting-proterozoic Snowball Earth, when the world was nearly totally covered in ice down to the equator (1). Neoproterozoic Snowball Earth (1) does not argue for low climate sensitivity for a number or reasons. Firstly, the world a quarter three quarters of a billion years ago was not the same as it was today, the Sun was 4-6% cooler than today, and the continental distribution was different (which alters ocean currents and their heat distribution amongst other things, as well as the rate at which CO2 is removed from the atmosphere). Secondly, the cap carbonates are from the end of the glaciation, when the ice was melting/had melted (3). The important point is that the glaciation began and grew when CO2 was low(1). Eventually the whole world was covered in ice, up to the tropics (whether the topical seas were icy or not is still controversial). A bit like Hoth, but without the rebels (or any large organisms, evidence for any sort of metazoans, let alone anything bigger and more complex than a slime mold then is pretty thin).

Permian glaciation scratches on Neoproterozoic rock at Hallet Cove.
Neoproterozoic glaciation scratches at Hallet Cove.

This has two consequences. One is that the Earth is very highly reflective, which means that a lot of radiation which could potentially warm the planet is reflected directly out into space. Remember that CO2 acts by trapping the longwave radiation that is emitted by the earth after it has absorbed the shorter wave incident solar radiation. With the Earth covered in glaciers, the snow almost acts like a mirror reflecting the incident short wave radiation back, with very little long wave radiation for CO2 to trap.

The other is that the weathering processes which remove CO2 from the atmosphere effectively had stopped (new CO2 is constantly being injected into the atmosphere by volcanoes and similar geophysical processes).

These two factors combine. The first (a highly reflective Earth) means that you need a lot of CO2 to warm the Earth to melt the ice, and the second means that a lot of CO2 will build up during the Snowball Earth until the melting point is reached, and then beyond until the excess CO2 is removed by weathering and formation of cap carbonates. Moncktons’ claim that this shows that climate sensitivity to CO2 must be low in this scenario is dead wrong, in fact simulations show that with the sensitivity most researchers claim for CO2, you still need a huge amount of CO2 to melt a Snowball Earth with a fainter Sun (1,2 and the measured CO2 after the glaciation ended was around 12,000 ppm, not 300,000 as was apparently claimed in Mocktons’ talk, 3). With a low climate sensitivity, the Earth would never unfreeze.

Now, you would have to be pretty canny to know about the Snowball Earth, it doesn’t come up much in the discussion of climate change in the recent epochs, but as a bit of a paleo-wonk and having stood on scrape marks caused by Snowball Earth glaciers I’ve had an interest in Snowball Earth, so I am familiar with some of the issues here (and you can get Celestia add-ons for a Snowball earth). Tim wasn’t (but who would be, and still be familiar with the telling points Tim had found?) and was caught on the back foot. Despite his being able to come up with a very pertinent point (that the Sun was dimmer then), it was hard to dent Moncktons’ confident presentation, even though the facts are almost the exact opposite of what Monckton claimed.

Again, this points to the core problem, showmen like Mockton can confidently spout off numerous factoids and misrepresentations in minutes, each one of which requires several minutes to refute. Tim got in several other good points (especially showing how Moncktons’ claims for low climate sensitivity were diametrically opposed to his fellow traveler Ian Plimers’ claims which require high climate sensitivity). However, despite Tim being right on the science, to people with no scientific background, it’s just a “he said” “she said” show, and Moncktons’ showmanship wins hands down, despite several of his critical claims being soundly refuted by Tim.

This is why generally, researchers refuse to debate Creationists. It is very hard to win, no matter what, the results are always spun against you, and the debate is used as validation for their position (you are debating them; therefore they have a legitimate point). In the case of the Monkton-Lambert debate, it was spun is just that way, being presented as Tim being the only one brave enough to debate Monckton (what was the Monckton-Brookes debate then? Chopped liver?)

This was also very pertinent to the SA Science Communicators presentation on Monday on Communicating Risk, where there was a lively debate on how scientists and researchers should tackle people like Monckton. Sadly, amongst other things it appears that researchers have been so badly burnt by the media they don’t want to enter into these kinds of discussions for fear of misrepresentation.

Good on Tim for getting up against Mockton, no matter what, there was no way he could win, even his mere appearance was spun as a win for the “skeptic” side. But he did serious damage to one of Moncktons’ show pieces. Hopefully that information will percolate through and maybe Monckton will stop misrepresenting Pinker et als research. Hopefully also we can stop Monckton from doing more snowjobs with Snowball Earth.

*Well, actually around 650 Million years ago (3).

References (note the titles):
1. Hoffman, P. F., Kaufman, A. J., Halverson, G. P. & Schrag, D. P. A Neoproterozoic
snowball Earth. Science 281, 1342–1346 (1998).
2. Pierrehumbert, R. T. High levels of atmospheric carbon dioxide necessary for the
termination of global glaciation. Nature 429, 646–649 (2004).
3. Bao, H. M., Lyons, J. R. and Zhou, C. M. 2008. Triple oxygen isotope evidence for elevated CO2 levels after a Neoproterozoic glaciation. Nature, 453, 504-506.

Update: Orac has some pertinent thoughts on debating "sceptics" here.

Labels: global warming sillyness, science communicators