Snowball earth refutes low climate sensitivity

This story is a bit old now, but it suggests methane may have been the principle greenhouse gas ending snowball phases anyway.

Methane sounds more likely and not CO2. We may need to produce a lot of methane in the near future, because our future is looking bleak.

http://jonova.s3.amazonaws.com/graphs/lappi/Gisp-ice-10000-r..png

The methane one was an old result. I found something newer that puts CO_2 at an upper limit of 80,000 ppm but with a wide range of uncertainty (12,500-80,000 ppm, with a possibility that something else was causing the effect measured). 300,000ppm is not supportable by anything I've read.

The mechanism for snowball earth: silicate weathering requires liquid water, which is mostly not available in the right place in a snowball earth, so volcano outgassing is not consumed by weathering, and slowly builds to the point where the greenhouse effect even without water vapour (in minimal quantities at around -40..-50C) becomes strong enough to melt the ice.

This is all a radically different scenario to today's world where total climate sensitivity includes feedbacks such as melting ice and water vapour. The snowball earth would have neither for a long period, before things warmed enough for enough warmth to produce water vapour and changes in albedo to take effect.

I recently read Svensmark and Calder's book "The Chilling Stars", and they suggest the snowball earth was due to galactic cosmic ray induced cloud increasing the Earths albedo. Funnily enough they don't explain how the Earth unfroze again. It seems to me that if the clouds dispersed when the GCR flux fell, the glaciated surface would have an albedo similar to a planet with complete cloud cover, so there would be no cange in albedo and it would stay frozen. Sadly they claim CO2 is feeble, which leaves a bit of a hole in the argument somewhere (unless it was the methane).

Which, in fairness, some of us said at the time. Monckton is not just a weasel, he's blindingly stupid about science and probably unstable.

http://media.caltech.edu/press_releases/12723

[T]he California Institute of Technology research group that originated the Snowball Earth theory has proposed that the culprit for the earliest and most severe episode may have been lowly bacteria that, by releasing oxygen, destroyed a key gas keeping the planet warm.

I can just see one cyanobacteria monckton sociopathus talking to another c. monckton: "Look, it's absurd to think that we tiny creatures can be changing a whole enormous world! Only Godteria has that power! I say consume the CO2 now and tell the grandcells, sorry, we spent your inheritance! Besides, oxygen is not a pollutant - look at the pretty colors it makes the rocks turn. Anyway, the acritarchs say it was far colder in the Tonian Cooling Period."

BTW the gas in question is methane, not CO2, so it may well have been methane at both ends. Much like Monckton.

el gordo @ 2
I noticed that you posted that link on [Bolt's blog](http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comme…) as well as the following

A cool PDO and limited sunspots will see the warmists out the door. I told them not to build those desal plants, but would they listen? No!

So we have a repeat performance of the 1946-75 period, with more La Nina. If BOM fails to warn the population of impending massive floods, then in my view they are bordering on criminal negligence.

el gordo of bathurst
Thu 18 Feb 10 (11:38am)

I thought I would try the Jonathan Leake/David Rose approach and came up with

POT CALLS KETTLE BLACK. PROLIFIC BLOG COMMENTER AND CLIMATE CHANGE DENIER EL GORDO DOES U TURN AND PREDICTS CLIMATE DISASTER.

I have always held the view that we are heading into another LIA, but the Bolter is a 'non alarmist' and ignores me. As do all his supporters.

Floods we can expect because there will be more La Nina in the coming decade. Proxy data suggests the Murray Darling system was in flood around 1780 and it was as deep as the Rhine.

If you think it can't happen again, then you are deluding yourself.

Philip Machanick wrote:

The methane one was an old result. I found something newer that puts CO_2 at an upper limit of 80,000 ppm but with a wide range of uncertainty (12,500-80,000 ppm, with a possibility that something else was causing the effect measured). 300,000ppm is not supportable by anything I've read.

This is a follow on from the paper in Nature (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) by the same first author that I use in my analysis (and is mentioned in one of my links). The range is higher than the Nature paper (5,00-30,000, average ~12,000), but the environment is more unusual, so I'd be careful accepting the highest levels. Still, even at the highest levels in these studies, it's nowhere near Moncktons' figure, which apparently comes from Plimer which in turn appears to be a theoretical figure for the upper limit of the amount of CO2 to melt a "Hard" Snowball Earth with no free tropical water (Pierrehumbert, R. T. High levels of atmospheric carbon dioxide necessary for the
termination of global glaciation. Nature 429, 646â649 (2004)).

Regardless of how Monckton came by the figure, the important points are a) The glaciations did not form during high CO2, the high CO2 was a consequence of the near total glaciation of the Earth and terminated that glaciation. The actual figures for CO2 and the deglaciation suggest that climate sensitivity must be at least what most people calculate (not Moncktons' low figures), if not a bit higher.

One has to think of CO2 doublings when trying to understand just how much GHG would be required to end a snowball glaciation.

The estimated average global temperature of the last snowball (650 to 635 Mya) was -20C to -25C.

It would take 10 to 12 doublings (at 3.0C per doubling) for CO2/GHGs to end the event - that would be 286,000 ppm to 1,146,000 ppm.

There is not enough CO2 outgassing from volcanoes to approach those kind of numbers over even 30 million years.

One needs to invoke continental drift to explain the snowballs - supercontinents conglomerate at the poles, glaciers build up, a runaway Albedo effect occurs, Albedo increases to 0.5 from about 0.3 today - snowball ends when supercontinent breaks-up (as they eventually do), continents drift away from the poles, Albedo declines again, ice melts, Albedo gets back to 0.3 by 590 Mya.

The continental drift reconstructions for the period are very close to this scenario.

http://en.wikipedia.org/wiki/File:SnowballGeography.gif

http://www.meteo.mcgill.ca/~tremblay/Courses/ATOC530/Hyde.et.al.Nature…

http://www.snowballearth.org/Bao08.pdf

el gordo, as modest as ever, writes, "I have always held the view that we are heading into another LIA"

Attention everyone! Given el gordo's immense reputation in climate science (= zilch) and science in general (= zilch again), we all must listen to him and hang on every word he says!

Seriously now. With no disrespect el gordo, your views aren't worth beans. You appear to glean much of your worldview from contrarian blogs. Got nothing better to do?

PaulW

"It would take 10 to 12 doublings (at 3.0C per doubling) for CO2/GHGs to end the event - that would be 286,000 ppm to 1,146,000 ppm.

There is not enough CO2 outgassing from volcanoes to approach those kind of numbers over even 30 million years."

Sorry to have to point this out, but you could have volcanoes outgassing nothing but CO2 for a billion years and not get 1,146,000 ppm :-P

Contibution from methane has got to be important. How long would it last in the atmosphere under snowball earth conditions?

It would take 10 to 12 doublings (at 3.0C per doubling) for CO2/GHGs to end the event - that would be 286,000 ppm to 1,146,000 ppm.

This assumes the approximately logarithmic effect of CO2 holds for really high concentrations, right? That's not necessarily the case. Consider Venus.

But, ENSO is caused by volcanoes on the ocean floor of the equatorial eastern Pacific don't you know. It must be true Lord Munchkin said so. (sarc). So Lord Munchkin himself says that PDO and ENSO are not linked, b/c ENSO is caused by volcanoes. Sadly he has not heard of the delayed oscillator.

Now I'll start preparing for the LIA that the denialists keep going on about (sarc). Perhaps they are convinced we are entering a LIA because they refrain from observing the facts:

http://earthobservatory.nasa.gov/IOTD/view.php?id=42392

Oh, and solar activity has increased dramatically the past few months, and NASA scientists say that we are not in for a Maunder type minimum.

http://science.nasa.gov/headlines/y2009/17jun_jetstream.htm

The ignorance of trolls who come here on climate related issues is quite astounding, as are those of Lord Munchkin and climate sensitivity. The deniers have tried to show that climate sensitivity to doubling CO2 will be very low, and thus far, all have failed. Anyhow, the doubling of CO2 is arbitrary, we are easily going to more than double CO2 if we continue at this rate. Perhaps they should consider scenarios for tripling of CO2 in AR5.

"It would take 10 to 12 doublings (at 3.0C per doubling) for CO2/GHGs to end the event - that would be 286,000 ppm to 1,146,000 ppm."

But if climate sensitivity is, say, 5.0C, then you'd only need about 6 doublings, which would be about 18,000 ppm. That's right within the estimated range.

Of course, it's likely that methane or other factors were involved, and that climate sensitivity isn't quite that high. But we're increasing methane concentrations too, so I don't know how this is a valid dodge by the likes of Monckton.

There are basically three proposed mechanisms, volcanism, inflowing comets and build up of CO2. Essentially no one can get any single one of these to work and the timing is wrong (big volcanic events occur more frequently than the snowball lasts for example) or the best you can do with the forcing is still too little.

While talking in front of a poster at AGU it occurred to Eli that you need a triple coincidence. No single one works. The person to comment intelligently on the topic is Ray Pierrehumbert who has done a great deal of work on the issue.
.

>*This assumes the approximately logarithmic effect of CO2 holds for really high concentrations, right? That's not necessarily the case. Consider Venus.*

Joeseph, Have you go any more details on the relationship change on Venus?

@el gordo

Nice graph. What the hell is up with having a categorical X-axis? And exactly what kind of curve-fitting are you doing?

Give a thousand monkeys Excel instead of typewriters, and this is the result.

And exactly what kind of curve-fitting are you doing?

If scientists fit a curve that shows global temperature is rising, it's proof positive that their predictions that temperature will rise more in the future are merely based on bogus statistical tricks, such as curve fitting. They just blindly assume that global temperature will follow their curve in a show of religious fervour. That's just nuts!

But if non-scientists fit a curve that shows the temperature in one spot is falling, then everyone knows that (a) the curve predicts the future temperature, and (b) it applies globally. Furthermore, in some mysterious quantum observer wave collapse simultaneity linkage mechanism thingamyjiggery, the climate knows the type of curve that was fitted, so if those non-scientists choose (say) a quadratic to make the curve drop even more sharply at the end, the climate will respond to match.

How could you be so stupid as to not know these basic climate facts yet?

;-) ;-)

I suppose the natural log relationship between temp and CO2 could be hard to maintain when cosidering transition to and from a snowball Earth.

As Ian points out, a change in albedo changes the amount of longwave radition emitting from the Earth's surface. Thus feedback effect between albedo forcing and CO2 forcing would switch between postive and negative depending on circumstance.

With ice moderating the temperature forcing of CO2 until a threashold is reached then the relationship would switch from negative to postive feedback, and whoosh: Planet Hoth turns into the Dagobah System. Not a recipe for a smooth log relationship.

But with current Earth the ln-relationship should be slightly less irregular. The loss of ice will be relatively less (given our current starting point), and the "whoosh" may be somewhat tempered by the albedo rise with loss of (dark) tropical forests.

Unfortunately a smooth ln-relationship still has bad consequence for highly specialised civilisations.

Both the loss of ice and forests will bring a whoosh of CO2. Which might not matter to our modern specialised (complex) civilisation, depending if it collapses with the removal of services provided by global of troprical forest.

Surely Dr. Alley has some insight and thoughts on this?

El gordo,

[ Jo Nova's cherry picked data](http://jonova.s3.amazonaws.com/graphs/lappi/Gisp-ice-10000-r..png) dosen't seem to fit with this

You'll notice a consistancy with the gisp2 data above with the [Vostok data](http://i49.tinypic.com/2ym604h.jpg) for the same period.

But here is the news flash el gordo, the very slight and very slow 10,000 year cooling trend has been turned around dramatically. The ice age is postponed indefinately, read credible journals for updating news.

Thanks Janet.

I've just been visiting Google Scholar, following up Linda Sohl and others mentioned in Walker's Snowball Earth, to see how the modeling was going.

http://pubs.giss.nasa.gov/abstracts/2000/Chandler_Sohl.html

From my limited knowledge a 'slushball earth' seems the most likely, with methane a stronger forcing than CO2.

@Mapleleaf

Richard Alley gave a talk on CO2 forcing and the snowball earth at last year's AGU. You can hunt down the video of it at the AGU 2009 meeting website (it was an invited lecture).

We may have been through this before, but if El Gordo's predicting cooling, then an even-odds bet on warming in 10 years should sound attractive. I'll give 2:1 odds in his favor. Serious money though - token bets only show token levels of certainty.

Joeseph, Have you go any more details on the relationship change on Venus?

See this comment at RealClimate.org.

It's unclear to me if it simply changes with concentration or if it requires high pressure, which is the case in Venus. I'll have to play with spectralcalc.com some more.

Good to see a robust discussion of "Snowball Earth". However, the clear result is that Moncktons claim the high CO2 during the end of the Snowball Earth means that climate sensitivity is low is dead wrong.

Eli:

In addition to Ray, I would of course include Jeff Severinghaus, no?