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Top Skeptic, Prominent Scientist Agree on Likely Global Warming Scenario by 2050
CO2 and Climate ^ | May 9, 2004 | Patrick Michaels

Posted on 05/11/2004 7:56:43 AM PDT by cogitator

Observations Not Models

NASA’s James Hansen widely is credited as “the father” of the global warming issue because of his 1988 congressional testimony concerning his detection of a human influence on world climate. His work with a General Circulation Model developed at the Goddard Institute for Space Studies led him to that conclusion, just as GCMs subsequently led others to the offer up “scary scenarios” of our climate future. It is remarkable, then, when Hansen writes in the March 2004 edition of Scientific American (PDF) that the climate change scenarios put forth in the Intergovernmental Panel on Climate Change’s (IPCC) 2001 Third Assessment Report “may be unduly pessimistic” and that the IPCC extreme scenarios are “implausible.”

In “Defusing the Global Warming Time Bomb” Hansen argues that the observed trends in atmospheric carbon dioxide and methane concentrations for the past several years fall below all IPCC scenarios. As a consequence, he concludes, future temperature rise will most likely be about 0.75ºC over the next fifty years.

In reaching this conclusion, Hansen relies on simple empirical evidence he considers more precise and reliable than model results “because it includes all the processes operating in the real world, even those we have not yet been smart enough to include in the models.” As a consequence, he and the University of Virginia’s Patrick Michaels, a climatologist characterized by many as representing the opposite pole of scientific opinion on this issue, find themselves in agreement.

Michaels, like Hansen, believes the IPCC scenarios in large part overestimate the potential temperature rise in the coming century. And like Hansen, Michaels relies on observations for his insight into future climate behavior. In his 2002 Climate Research paper “Revised 21st century temperature projections,” Michaels writes, “[Observations] are the perfect integrators of all processes that are currently active” and thus avoid the “varying degrees of uncertainties surrounding every aspect of the models.”

Michaels used observations of the rate of the observed buildup of carbon dioxide in the atmosphere, along with observations of the global temperature change during the past twenty-five years or so, to determine, “Our adjustments of the projected temperature trends for the 21st century all produce warming trends that cluster in the lower portion of the IPCC TAR range.” Michaels concludes the warming during the next fifty years will be somewhere near 0.75ºC — precisely the conclusion at which Hansen arrived two years later. Sadly, this is where most of the agreement between the two climate researchers ends. Note from the poster: this is double the rate of warming in the 20th century.

Hansen says it is imperative that we undertake concerted and organized efforts to lower this warming rate even further in order to avoid what he describes as “dangerous human interference” with the climate system (thereby echoing the words of the 1989 United Nations Framework Convention on Climate Change, a/k/a the “Rio Treaty”). He declares the “emphasis should be on mitigating the changes rather than just adapting to them.”

Michaels argues such a likely and modest temperature rise is one to which earth and its inhabitants can readily adapt. He contends it may even offer great advantages — longer growing seasons, reduced heating costs, enhanced global vegetation, and so forth. Because the rate of climate change is manageable, Michaels believes, it isn’t necessary to induce changes in the global energy structure. He advocates allowing market forces to dictate change because fossil fuels are finite and mankind will have to develop alternative energy sources.

How can two scientists who base their conclusion upon a collection of empirical evidence end up so at odds?

Hansen says his biggest concern is the potential for a large rise in sea-level. Yet empirical evidence shows that the rate of sea-level rise over the course of the 20th century (during which there was about 0.75ºC of warming) was about 1.8 mm per year. Therefore the cumulative rise over the past 100 years has been about 7 inches. Double that rate, as implied by a continued steady rise in temperature, and in most places there are no problems that cannot be controlled or adapted to. **see note below in comment

Other lines of evidence demonstrate the potential for positive impacts. Research by Ramakrishna Nemani and colleagues (who studied variations in global vegetation patterns based upon data collected from satellites) shows a remarkable enhancement of the growth of global vegetation. They attribute the growth to two decades of change in the climate and to the increased atmospheric concentration of carbon dioxide, which acts as a plant fertilizer.

The litany of dire consequences that could result from global warming generally is in step with the magnitude of the warming. In the IPCC’s Third Assessment Report the range of potential warming manifest by 2100 is presented as being between 1.4ºC and 5.8ºC. The IPCC does not indicate which value is more likely. However claims of drastic future consequences are based upon the possibility of temperatures ending up on high end of the IPCC range (for instance see the claims made by the environmental organization The Bluewater Network which are reportedly behind some recent climate actions by Senators John McCain (R-AZ) and Ernest Hollings (D-SC), http://www.co2andclimate.org/wca/2004/wca_14c).

If one looks at actual evidence (rather than modeled responses), as do Hansen and Michaels, it is the lower end of the range that is more likely. The impacts associated with warming at the low end of the IPCC TAR range are far less dramatic and infinitely more manageable than those that accompany high-end warming.

It seems about time to dispense with the notion that future warming will be catastrophic and begin to focus on the implications of a modest warming where benefits are likely to outweigh costs.

(click on article link for references)


TOPICS: Culture/Society; Editorial; Government; Miscellaneous; News/Current Events
KEYWORDS: change; climate; climatechange; science; skeptic; warming
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To: kidd
It sounds as if Micheals is being disengenuous, but this statement by Hansen is disingenuous as well. This period of most rapid melt also occurred when glacial ice was located as far south as the Washington DC region and is not applicable to the present day scenario where glacial ice is found only in Greenland and Antarctica. And rapid desalination of the North Atlantic from this melting of mid-latitude glaciers would have accelerated the warming/melting of glacial ice. Also not applicable to present day scenarios - but Hansen implies that the present day warming trend will similarily affect near-polar region glaciers.

In reading it closely, I think Hansen is aware of the difference. Note that he says "Given the present unusual global warming rate on an already warm planet..." That statement implicitly acknowledges that the termination of the last glacial occurred on a "colder" planet. I believe that the point of that section is that warming temperatures will likely result in increased ice melt (and he also notes his own research that the deposition of a small amount of black soot on ice increases the absorption of sunlight on the ice surface, contributing to an increased melting rate as well.)

61 posted on 05/11/2004 2:45:30 PM PDT by cogitator
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To: cogitator
Now the modelers can turn their efforts to Mars and explain how a planet with an atmosphere that's 95% CO2, manages to stay cold rather than have runaway greenhouse warming.
62 posted on 05/11/2004 2:49:11 PM PDT by <1/1,000,000th%
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To: cogitator
It's directly related to your claim that temperature changes apparent since 1800 are occurring over a faster time scale than had ever before occurred.
63 posted on 05/11/2004 2:56:24 PM PDT by .cnI redruM (Training doesn't give you common sense or respect for human dignity.)
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To: Final Authority
Exactly
64 posted on 05/11/2004 3:42:09 PM PDT by Conspiracy Guy (Proudly not proofreading since Jan 1954.)
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To: taxed2death
Beachfront property? Me too. But I'm trying to decide what kind of boat to have at my dock. Power? Or sail? By the time it happens, I think I'll prefer the convenience of a powerboat. I'll shop around for a Donzi - something that goes at least 70 mph. Since they only get about 3 MPG, it will create more global warming and then I'll have more beachfront property.
65 posted on 05/11/2004 4:31:40 PM PDT by henderson field
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To: cogitator
I've now read not only the article but Hanson's original paper. It is more elaborate than a correlation but not by much, and relies on some poor reasoning to fix climate sensitivity too fast. Without paying any attention to the physical limits on temperature response to a given level of forcing.

First he estimates long ice age forcing as 6.6 watts below now. This is based entirely on changes in atmosphere composition and large surface factors (albedo, in effect). Which we can know for these remote periods from things like ice core data.

Problem - we do not remotely know that the 6.6 watts we can ID are actually all the power sources that changed between an ice age and now. To infer a 0.75C per watt sensitivity from this is not warranted. Other than triggering atmosphere and ice changes, he ascribes nothing to changed solar forcing, ice ages to now.

The physics of it say 6.6 watts can't do that. There is far too much power coursing through the system just to maintain the baseline 285-290 K temperature. A 5 C change requires a 7% power term change. If 6.6 watts were 7% of the real total, the total power would be 94 watts. Direct sunlight at the edge of space is 342 watts. This is wrong, empirically.

Physics does not say you won't get 6.6 watts from changing atmosphere and ice sheet stuff. That sounds entirely plausible. But in the old data, temperatures take off well before the atmosphere responds. This 6.6 watt measure is almost certainly the positive feedback, not the entire signal that causes ice ages.

It might be 20% of the signal, roughly split between 10% land-ice-albedo and 10% air-CO2etc-greenhouse. You'd have a 25 W driver, and these 3 W feedbacks piling on. That would have the driver 35 watts, fitting an estimate of 500 W to maintain temperature now (sunlight plus greenhouse etc).

Maybe it is as high as a third of the signal, 20 W overall, with albedo reducing sunlight etc. But that is a lower bound (it is just sunlight times a .83 albedo - the earth could have that much power with no atmosphere at all). Then the picture of ice ages would be, you get a 13 W driver from the sun, and you tack on 25% feedback sizes from albedo and atmosphere feedbacks.

Those ranges suggest climate sensitivities, reduced to one coefficient, in the range 0.25 to 0.15 C per watt. It is critical to understand that the only thing he has, up to this point in the argument, supporting the idea that instead it is 0.75 C per watt, is the notion that the 6.6 W he can ID from ice core data are the entire forcing for ice ages. This is the old, one would have thought by now discredited, idea, that ice ages are caused purely by atmosphere (and ice sheet) changes. It is just now dressed up as empiricism - since I can measure these factors 100,000 years ago, they must be the driving factors in ice ages, and the same sensitivity should be expected today.

But we also just know this isn't the real ice age story. Because these 6.6 W he can ID, show up after the warming starts. Not only is the amount too small on physical considerations, but it comes at the wrong time to set off the escalating temperature run (low level during, big only after them). Clearly the real power driver comes before them and it is just plain missing from his budget.

Why does this matter? If the same measures are used now, won't the relation be the same? No. If the other factors are follow on feedbacks to the ID-able 6.6 Ws, they might be the same now as then. But if they are solar, they aren't feedbacks at all, aren't driven but driving, and CO2 changes today are not going to set them off.

Then - 13 to 25 W from unmeasured sources, touching off 6.6 W from measured sources. Now - less than 6.6 W from the same measured sources, and no reason to believe the bigger unmeasured one is operating at all.

So, first understand, there is good physical reason to believe the power needed to drive ice ages is higher than his budgeted 6.6 W, more like 20-35W. Which imply climate sensitivities on the order of 0.15 to 0.25 C per W, not 0.75.

Now turn to the modern data. He gives his estimate of forcing factors from roughly 1850 to 2000. He gets 1.6 plus or minus 1W. If you look at the individual error bars of the internals, then going half way high yields 2.9W, and all at their 1 SD lines gives 4.2W. Thus -

His centerpoint - 1.6 W
Within his error bar - 2.6 W
Within 1/2 on all - 2.9 W
Within 1 on all - 4.2 W

Why does this range matter? Because we have an observed temperature change to set against the forcing estimates. It is 0.75C - although some say it is more like 0.6C, the former is the figure he gives. Well, that means the implied sensitivity coefficients run from 0.47, to 0.29, to 0.26, to 0.18 down to 0.14 if you use 0.6C as well. But none of them support 0.75. 0.15 to 0.25 is physically believable territory, not needing large unknown power terms. I'd have no difficulty allow small ones, bumping the range up to 0.3 to 0.375. My range estimate, certainly wide, would be 0.15 to 0.375.

But his own data for this modern period do not support the 0.75 he got from the ice ages - his own centerpoint of 1.6W forcing gives 0.47 on his high estimate of the temperature change. Yet all the later model run comparisons use 0.75. Which is twice to five times what makes physical sense and lies within his own error bars.

Understand just what that +/- 1W contains. It means a range from 0.6 to 2.6 - a factor of 4.33 times. We've also got maybe a 0.25 range factor in the temperature measurement (0.6C to 0.75 C). Put them together, and the estimate of the climate sensitivity is varying over a factor of 5, within the error bars. With only the low end of it compatible with physical considerations (absent giant unseen and unnamed additional power terms).

When we come to projected future changes he sees 1.5 W additional forcing. He tosses in an extra 0.5 W for no strong reason, about an unknown and to get closer to IPCC. Call it 1.5 to 2.0 W. That means 0.47 (his own data) say 0.7C to 0.95C, while his ice age induced 0.75 gives 1.1 to 1.5C.

My range and the same forcing predicts 0.23C to 0.75C. Physical considerations alone say 0.23C to 0.5C - the higher possibility reflects an implicit allowance for as yet unseen feedbacks, but smaller ones than the signal. For his 0.85W forcing optimistic emissions controlled case, I'd give 0.13 to 0.32C with 0.13 to .21 most likely.

Personally I doubt forcing will be that small and do not see reason to seek it with draconian regulation. He thinks for ice sheet and sea level management reasons the temperature change from today should be held to under 1C. But his own estimate of 1850 to now forcing would do that (0.47 sensitivity, with 1.5 to 2 W future forcing). I think the sensivity is half of that and a third of his ice age figure. And I'm well within his error bars for 1850 to 2000 believing it. I'm also compatible with the power needed to maintain a higher temperature.

The epicycles are falling away, but he is still clinging to the ice age theory to justify the 0.75 sensitivity figure. Which is physical nonsense if meant to describe all the power sources needed. Ice age nonsense in that it acscribes the entire change to factors we know lag the actual temperature changes in ice ages.

There is simply no good reason to think the temperature response is so high, and plenty of reason to think it is appreciably lower. His own 1850 to now estimates give a figure 37% lower; his error bars there are huge and accomodate much lower still; physics alone says 65-80% lower.

66 posted on 05/11/2004 4:43:37 PM PDT by JasonC
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To: Deb
:)
Oh...I forgot about those cows!
67 posted on 05/11/2004 5:47:03 PM PDT by FBD (...Please press 2 for English...for Espanol, please stay on the line...)
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To: cogitator; farmfriend; Carry_Okie
Ah, but what Hansen may be failing to factor into his calculations is all the additional hot air (and, in some cases, even 'methane') being generated by all the Chicken-Little crowd's jawboning on this subject.

I suspect that the most dangerous 'global-warming effect' is more likely the destruction of our economy by those who are "well-meaning, but without understanding" trying to 'fix' it, than any possible risk of us all drowning in seawater and/or melted glaciers.

...Yeah, now that you mention it, I guess you're right... I'm really NOT too certain about that 'well-meaning' part I guess...)

"The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with a series of hobgoblins." -- H.L. Mencken

"If a million people believe a foolish thing, it is still a foolish thing." -Anatole France

Can I share these here...?

More??? ...Please see...: Seadog Bytes at StrangeCosmos.com

68 posted on 05/11/2004 6:10:50 PM PDT by Seadog Bytes ("Smart Growth... Isn't.")
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To: cogitator; farmfriend; Carry_Okie
My apologies. Although, after reading the rest of this thread, I am left with my initial impression - that allowing politicians to attempt to try to 'fix' global climate change is likely more dangerous to our overall welfare than those changes themselves, it is now evident to me that this discussion is WAY to serious for the post I just submitted. Sorry to intrude. Lesson learned.
69 posted on 05/11/2004 7:18:33 PM PDT by Seadog Bytes ("Smart Growth... Isn't.")
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To: Seadog Bytes
Comedy is always welcome.
70 posted on 05/11/2004 8:14:06 PM PDT by farmfriend ( In Essentials, Unity...In Non-Essentials, Liberty...In All Things, Charity.)
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To: Straight Vermonter
Neither the Post nor Watson mentions that this forecast of extreme warming is the result of a computer model. And not just any model, either. It is a product of the most extreme climate model run under the most extreme set of future emission scenarios. In other words, it's not a model based upon present trends; it's a model of a model! Putting a fine point on it, this particular result was produced by one (that's right, one) of 245 models the modelers ran.

And that particular model was intentionally tweaked to ignore known negative feedback mechanism which counteract global warming. In other words, the IPCC intentional puts out bad data to feed the scare-mongerers. The IPCC are the lowest form of scum.

71 posted on 05/12/2004 5:35:53 AM PDT by Always Right
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To: <1/1,000,000th%
Now the modelers can turn their efforts to Mars and explain how a planet with an atmosphere that's 95% CO2, manages to stay cold rather than have runaway greenhouse warming.

There's also a slight matter of atmospheric density and the amount of water vapor in the atmosphere. Water vapor is the primary greenhouse gas.

72 posted on 05/12/2004 7:28:56 AM PDT by cogitator
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To: .cnI redruM
It's directly related to your claim that temperature changes apparent since 1800 are occurring over a faster time scale than had ever before occurred.

You misconstrued my point. I was answering the question about how the initiation and termination of glacial epochs occurred. The increase in global temperature since 1850 is more rapid by about a factor of two, over a period of about a century, than any other rise or fall in global temperature in the last 1000 years. What this means is that an increase of approximately 0.6 C in 100 years is double the rate at any other time (i.e., the maximum trend up or down over 100 years has been 0.3 C or less). This does not mean that there have not been more rapid temperature excursions (such as after a major volcanic eruption) where the rate of increase/decrease would have been much more rapid if extrapolated over 100 years. (If you have a 0.2 C drop in two years due to a volcanic eruption, that would be a 10 degree drop in 100 years -- which only happens if there is a major ocean current regime shift.)

I stated all that to explain why there isn't a discrepancy between what you say about the 13th and 14th centuries and what I said.

73 posted on 05/12/2004 7:36:11 AM PDT by cogitator
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To: cogitator
I agree. It's more complicated than simply the percent of CO2 present.

I was being facetious.
74 posted on 05/12/2004 8:24:33 AM PDT by <1/1,000,000th%
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