Anthony Watts and Patrick J. Michaels had a miss on WUWT yesterday, so they are trying again. This time with the help from Paul C. “Chip” Knappenberger. Once again it's tactic of appealing to the fear factor that by all accounts is one of the main causes of disability of science deniers.
By way of introduction, research suggests that the fear factor prevents some people from rational thought. There is a strong association between this impediment and conservatism. Fear causes cognitive dissonance which is only allayed by allaying the fear. That becomes the priority. When threatening facts can't be refuted then anyone who misrepresents the facts and lowers the fear becomes the new messiah. It doesn't matter how wrong they are. The fact they've reduced the fear is sufficient for the professional disinformer to be hailed as a hero.
Strike One: Unveiling The Strawman
First the build up. Pat and Chip lead in with this, referring to Dr James E Hansen:
Specifically, he believes global average sea level will rise some 15 to 20 feet by 2095.The question is, does Dr Hansen really believe this as a foregone conclusion? Pat and Chip refer their readers to this book chapter by Hansen and Sato1. Even a cursory read shows that the authors are not at all categorical. What the authors maintain can be read in the abstract (my bold):
Gravity satellite data, although too brief to be conclusive, are consistent with a doubling time of 10 years or less, implying the possibility of multi-meter sea level rise this centuryHe believes vs implying the possibility of. What Pat and Chip have carelessly done is build a strawman.
That's easy to do for the WUWT crowd who thrive on their disdain of climate science and especially of climate scientists and most especially of three or four climate scientists in particular. James Hansen and Michael Mann are at the top of their list. But the strawman really wasn't necessary.
Indeed the entire article wasn't necessary. One word would have sufficed.
Pat and Chip - all you have to do is write the single word "Hansen" and the deniers go rigid with rage, their faces twisted into a slathering snarl, the words on the screen melt together in a blur and their hands are clenched so tightly they can barely unbend their fingers to type in the WUWT comment box. The relief after clicking "Post Comment" is profound, and surges through their body. They take a deep breath and wait avidly for someone, anyone to acknowledge their intense feelings expressed variously as - "only in it for the money", "activist", "gravy train", "CAGW", "hoax" and "scam". (Yes, a bit of a let-down, isn't it :))
Don't believe me? I wrote the above in advance of any responses to the article - now go check the comments.
Strike Two: Geography Fail
After that little diversion, back to what Pat and Chip did. The straw man is built, now they try to knock it down. I won't bore you with details of "another scientist said something therefore Hansen is wrong about everything", which is the basis of their argument. I will point out that they are not crash hot at geography or logic. Here is how I know. Pat and Chip quote this passage from the Hansen and Sato chapter (with a couple of words changes for some reason):
However, the primary flaw with the kinematic constraint concept is the geology of Antarctica, where large portions of the ice sheet are buttressed by ice shelves that will not survive BAU climate scenarios. West Antarctica's Pine Island Glacier (PIG) illustrates nonlinear processes coming into play. The floating ice shelf at PIG's terminus has been thinning in the past two decades as the ocean around Antarctica warms Shepherd et al., 2004). Thus the grounding line of the glacier has moved inland by 30 km into deeper water, allowing potentially unstable ice sheet retreat. PIG's rate of mass loss has accelerated almost continuously for the past decade (Wingham et al., 2009) and may account for about half of the mass loss of the West Antarctic ice sheet, which is of the order of 100 km3 per year(Sasgen et al., 2010).Okay. This paragraph follows from a discussion of Greenland. Hansen and Sato are pointing out that West Antarctica is very different to Greenland. (These are the two locations of greatest concern in the near future in regard to near term sea level rises. That is, of the order of decades to centuries.)
While West Antarctica may be losing ice mass, East Antarctica appears to be gaining, as higher sea surface temperatures lead to more moisture in the atmosphere which leads to greater snowfall there.Even if they were correct about East Antarctica gaining some, what the heck has snowfall in East Antarctica to do with the potential risks of glaciers melting in West Antarctica? That's like saying people in San Fransisco don't need to be concerned about earthquakes because there's not much risk of a major earthquake in Boston. Look for yourself. Note the scale at the bottom and the mountain range separating east from west. (Click to enlarge):
|Source: NASA via Wikipedia|
If Pat and Chip make such a big deal about the Pine Island Glacier not being a problem because it's pretty darn cold in the middle of the high mountains in East Antarctica, then what else are they so wrong about?
Strike Three: And They are Out
Next Pat and Chip try to tell you that sea levels weren't higher in the Pliocene after all. Their evidence? This is what they write (by the way, prefaced with an "oops" - implying that Hansen and Sato should have read a paper published just two weeks ago, before writing their chapter two years ago):
Oops. Wrong again. Breaking scientific research just published online from the journal Science (Rowley et al., 2013) conclude that the apparent 25 ± 10 meter sea level rise during the Pliocene was probably due to vertical land motions during the intervening 3 million years rather than an actual sea level rise from more water in the oceans from melting ice (Hansen’s mechanism).Is that what the paper actually said? By all accounts, no. You can read the abstract here in Science Express, and the full article if you're a subscriber. The abstract doesn't say that sea level rise wasn't as high as thought, it says that you can't determine the sea level from that stretch of land because it shifted as a result of mantle flow. In other words, what is thought of as a "passive" shoreline was subject to movement. Let's see what the press release has to say:
"The highlight is that mantle flow is a major component in distorting the Earth's surface over geologic time, even in so-called 'passive' continental margins," Simmons said. "Reconstructing long-term global sea-level change based on stratigraphic relations must account for this effect. In other words, did the water level change or did the ground move? This could have implications on understanding very long-term climate change."This work may change estimates of sea level in the Pliocene or it may not. It depends on what other evidence suggests. But it seems to me that it doesn't necessarily negate higher sea levels. Nor does it tell us about sea levels in other eras when the earth was as warm as we're heading towards. I would have a lot less certainty than Pat and Chip that sea level rise will be benign - and I live 200 km from the coastline.
Where does that leave us?What Hansen is concerned about is that people will allow themselves to be lulled into a false sense of security, thinking that sea levels will rise only gradually and by 'only' a half metre or so this century. But glaciers in particular are slippery things - they can slide into the ocean, huge chunks can break off and there could be a sudden larger rise. Heck, imagine if instead of a twenty cm rise in a century there was a half meter rise in a decade. Imagine a storm surge or a cyclone. It's not going to be much comfort to inhabitants of coastal cities to say, sorry - we knew it was possible but we didn't think it was likely so we kept on burning fossil fuels.
Maybe the seas won't rise two meters this century. Maybe it won't happen for another 120 years. That would foist the problem onto our children's children. What will they think of us, knowing we could have prevented a sudden rise?
And what will half a meter rise in sea level mean? We might have only a few decades to relocate thousands of cities and billions of people to higher ground. That's an enormous undertaking. (Think of large infrastructure projects that can take anything from ten years to thirty years to completion.)
Here are the closing paragraphs from Hansen and Sato. Their projections are on the high side for the Business as Usual scenario. Does that mean we should ignore them in favour of projections that are less uncomfortable just because we prefer the latter? Surely that would be another logical fallacy - that of personal incredulity. (My bold and italics for emphasis.)
BAU scenarios result in global warming of the order of 3-6°C. It is this scenario for which we assert that multi-meter sea level rise on the century time scale are not only possible, but almost dead certain. Such a huge rapidly increasing climate forcing dwarfs anything in the peleoclimate record. Antarctic ice shelves would disappear and the lower reaches of the Antarctic ice sheets would experience summer melt comparable to that on Greenland today.
The other extreme scenario, FFPO, does not eliminate the possibility of multi-meter sea level rise, but it leaves the time scale for ice sheet disintegration very uncertain, possibly very long. If the time scale is several centuries, then it may be possible to avoid large sea level rise by decreasing emissions fast enough to cause atmospheric greenhouse gases to decline in amount.
What about the intermediate scenario, EU2C? We have presented evidence in this paper that prior interglacial periods were less than 1°C warmer than the Holocene maximum. If we are correct in that conclusion, the EU2C scenario implies a sea level rise of many meters. It is difficult to predict a time scale for the sea level rise, but it would be dangerous and foolish to take such a global warming scenario as a goal.The upshot is that sooner or later ice is going to melt and seas will rise. That is certain. The question is over what time scale. How long do we have and will it be sudden or gradual. Will there be sudden shifts over a few years. Do we want to take the risk? How lucky do you feel? How lucky will your grandchildren be?
1. Hansen, J.E., and Mki. Sato, 2011: Paleoclimate implications for human-made climate change. In Climate Change: Inferences from Paleoclimate and Regional Aspects. A. Berger, F. Mesinger, and D. Šijači, Eds. Springer.