Tuesday, July 11, 2006
Stalagmites And Myths: Global Warming
We have something of a classic chicken-and-egg problem in figuring out whether greenhouse gas (GHG) levels drive the cooling and warming associated with ice ages or whether changing temperatures alter the levels of the gasses. A warmer planet will have more GHGs in its atmosphere than a cooler one due to basic chemistry even if the GHG have no significant contribution to the temperature level itself. For example, if all major temperature change was driven completely by insolation, the GHG levels would rise and fall in trailing sync with the temperatures. If you could not measure insolation but only GHG levels, you might easily conclude that the changes in GHG were driving the change in temperature.The second link is to an excellent and extremely readable paper by McKitrick discussing the Mann hockey stick. It explains the problem clearly in 18 pages. See especially pages 5 containing the borehole reconstruction from the IPCC's 1990 effort and page 6 with another borehole reconstruction. ClimateAudit carries continuing debates along the same lines.
There exist about a 600-800 year lag in the end of ice ages and the rises in levels of GHGs. An even longer lag in the decrease in greenhouse gasses occurs at the start of some ice ages. Clearly, GHGs do not drive major temperature trends but merely amplify trends begun by other factors. It is the degree of amplification that is under question.
The weak correlation I mention is not between temperature and GHG levels (which is strong but largely irrelevant) but between GHG level change followed by temperature change. There is a stronger correlation between temperature change followed by GHG change than the other way around.
Some researchers believe that the cores confirm their computer models but the models were designed to fit the data curves of earlier ice core samples. Simplistically, the models may have just copied the shape of the general curves themselves without accurately modeling the actual natural forces involved. This kind of problem shows up in computer modeling all the time. For any data set, there are a large number of possible models which will generate that data set. In order to really test the model, you must use it to predict a data set that wasn't used in the creation of the model in the first place. I don't think this was done in this case.
I don't think the ice cores tell us much about global warming one way or the other. The time frames we are worried about are on the order of 100 years or less. The ice cores can't even resolve a time span that small. Its quite possible that a C02 levels briefly reached the levels we have now but were not captured in the ice. More importantly, the temperature swings associated with ice ages are massive and clearly driven by some powerful non-atmospheric factor. They really don't tell how much extra-heating we could cause by pushing already high C02 levels (compared to what they were at the end of the ice age) a bit higher.
The third link is to a 67 page paper by Soon and Baliunas reviewing the types of proxies and the evidence for a highly variable climate during the last 1000 years when compared to this century. This paper is particularly good because it discusses the different effects seen, resolution of different proxies, etc. The last 40 pages are occupied with references, so this shouldn't occupy too much of your time. The article points out the following:
It might seem surprising or frustrating that paleoclimatic reconstruction research has not yet provided confident and applicable answers to the role of anthropogenic forcing on climate change. This point is particularly sharp when considering the fact that even though some proxy records (e.g., those from Overpeck et al. 1997) show unprecedented 20th century warmth with most of the increase occurring in the early to mid-decades of the 20th century, when the amount of anthropogenic CO2 in the air was less than 20–30% of the total amount there now. Unless there are serious flaws in the timing of the early-to-middle 20th century surface thermometer warming, or unknown anthropogenic mechanisms that caused a large amplification of surface temperature of the then-small increase in anthropogenic atmospheric CO2, then the early part of the 20th century warming must be largely dissociated from anthropogenic CO2 emissions. Other anthropogenic factors still need to be studied on a case by case basis.In other words, the recent and less recent historical record shows that the earth has a highly variable climate. If anything, the historical reconstruction shows that CO2 increases seemed to occur hundreds of years after sudden warming, rather than to precede it.
It's not scientifically controversial that the oceans emit CO2 when warming, btw. Also CO2 in the atmosphere fluctuates significantly from one part of the year to the next every year due to growth-related CO2 uptake and decay emission. This site on the Mauna Loa record contains both a data table and a graph showing these fluctuations. It's also uncontroversial that burning fossil fuels is slowly raising atmospheric CO2, which, btw, is measured in parts per million.
The earth's climate is so variable that whenever you look at actual data, it is easy to generate an up or downward trendline depending on the beginning and end of the slices. For example, see this Junkscience-hosted Gulf of Alaska record:
There'a a reason it's called "Greenland"...it used to be...green.
And that sure wasn't from the Vikings driving around in SUV's or cavorting around the fjords on jet-skis.
Yes, the globe may indeed be warming...so what?
It's not worth giving up Chinese food and Pizza delivery for.
The globe would warm and cool anyway even if we reverted to being pedestrian cave-dwellers picking lice from each others' bodies, like Algore and Kyoto fetishists seem to want.
Two Pinatubos or Four Mount St. Helens eruptions would likely spew more greenhouse gases into the atmosphere than from every source of human combustion...ever.
Don't buy beachfront real estate and learn air-conditioning.
If we all disappeared tomorrow, the planet would warm and cool as it always has. That's true. I have some good stuff coming up on stalagmites.
As for beachfront property, think again. Given the relatively poor efficacy of CO2 as a greenhouse gas, it's quite likely that it will get colder no matter what we do. And that would mean the beachfront property will grow - which you must admit is an uncommon feature of real estate.
Just a thought. The Bilgegrandchildren might appreciate it.
The fact that we have had ice ages in the past and global climate changes before the industrial revolution does not change the fact that we our actions now are contributing in a major way to a global climate change. Time to either save the world or lose it.
"And that would mean the beachfront property will grow - which you must admit is an uncommon feature of real estate.
Just a thought. The Bilgegrandchildren might appreciate it."
No, thanks. As you know, I'm a N'Awlins boy, originally.
I don't need to be halfway around the world worrying about the Bilgefamily and the Chateau Bilge from hurricanes, tsunamis and spring break.
I don't think folks realize that that pretty ocean that they live next to is a wild, unpredictable, and heartless thing.
Besides...I spend enough time staring at the sea.
It's the mountains for me.
Old seaman's joke:
Fella says that when he retires, he's gonna hoist an anchor on his shoulder and start walking inland until some goober asks him what kind of new-fangled "plow" that is that he's carryin'.
That's where he "drops anchor", and doesn't move from the spot.
"While we may never be able to figure out the exact percenatage attributable to human activity, there's no question that it is substantial and that we can prevent a global crisis or precipate one."
Since you assert that "we" might not ever figure out what quanta "we" are contributing to this "crisis", how are "we" then supposed to decide on the necessary quanta of sacrifice that "we" must make to ameliorate the "problem"?
"The fact that we have had ice ages in the past and global climate changes before the industrial revolution does not change the fact that we our actions now are contributing in a major way to a global climate change. Time to either save the world or lose it."
Again with the first-person plurals, huh?
Screw the "we"...what are YOU willing to sacrifice?
Do you drive a car?
Do you have air conditioning and a refrigerator?
Do you use electricity?
Don't say "we", you lead by example. If this "crisis" really concerns you, then YOU must show us the solution by sacrificing the modern technological conveniences that you are urging the rest of us to give up.
IOW, if you won't walk the path alone to "save the planet", then get down off of the soap-box.
The truth is that given what we know about the earth's climate system now, we cannot predict whether it will be cooler or warmer in a century. That is reality.
I think what you mean to say is that we understand what changes we are introducing in climate and have accurately figured the relative weights of our activity, but that isn't true either.
For example, land use changes may well have more of an influence than atmospheric changes. The GCMs are works-in-progress and don't yet have much independent confirmation. They fail to predict climate changes in the past, and if they cannot even do that, then they cannot logically be used to predict climate changes in the future.
Trying to solve a problem that you don't understand is impossible unless you can afford trial-and-error, which we can't.
Our first problem is our lack of knowledge. I think we are on the road to acquiring that knowledge, and some of the recent work with stalagmites might be a big step towards that.
However the second problem is that even where we do know that we are having some effect, we don't seem to be psychologically able to make the logical changes based on our knowledge. Land use changes are largely off the board. There's nothing that the world today can do to correct the massive deforestation in China and India.
But CO2 emissions are addressable to some extent by our current technology, and a big part of that would have to be extensive use of nuclear power. Why is that not happening? It's impossible for any individual to adopt a "carbon-neutral" lifestyle in today's world unless you own a lot of land and plant trees. Unless we build nuclear power plants across the globe, we cannot ameliorate potential warming related to CO2. Still open is whether we want to or not, but I grant you that a conservative approach would be to try to make as little impact as possible on the environment. It may turn out to be the stupidest approach possible, but on the other hand it's one we could rapidly alter.
Potential anthropogenic climate changes are being discussed in the politically-scientific culture in a completely ascientific manner. That is an objective reality, which I am proceeding to support with this series of posts.
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