Interesting article about global warming. Thoughts?

[Kevin Scharfenberg]

Mike Smith wrote:

A question: How do we know which is which? If the forcing varies from year-to-year, decade to decade, century to century as you contend, how do we know which is the strongest forcing in 1600...1601....1602 or 2004...2005...2006?

Well we know the earth is an oblate spheriod with equatorial diameter 12.7 km, covered with 70.8% water, with an atmosphere composed of 78% nitrogen and 21% oxygen, and so on. We can take everything we know about earth and its atmosphere and the forcings that affect climate and run calculations, or use simple chemistry arguments, or use a variety of other methods, to show that increasing CO2 concentration into the atmosphere will increase the global average temperature by SOME amount.

Hopefully no one will argue that if I invented some hypothetical device capable of injecting enough carbon into the atmosphere to multiply the concentration of CO2 globally by 100 very rapidly and turned it on, the global average temperature would trend up rapidly with time. The only question is by how much.

Well we can run the discussed calculations in hypothetical mode, holding all other known forcings constant but multiply the amount of CO2 by 100, and get quantitative estimates with error bars about how the temperature would change.

This has been done countless times at countless institutions, and the calculations have turned out to be remarkably correct -- see predictions in Hansen 1988. In fact Hansen acknowledged that if a major volcano eruption happened, the predictions would be too high for 1-3 years until the fallout was complete, which is exactly what happened with Pinatubo a few years later. There's a nice divot below Hansen's prediction in the 2-3 years after Pinatubo and then the atmosphere rebounded to the continued warming state as Hansen predicted. Absolutely remarkable for how little we knew back then.

Anyway, the ice core samples have shown that we have a remarkably good handle on how the CO2 concentration affects global temperature (as shown by other proxy data at the same time), even if you believe the CO2 vs. temperature measurements over the last 50 years were a fluke. Obvisouly we cant know exactly what the solar state was in 1700 when we might have some ice core sample, but we know what the RANGE of values of solar activity are, and we have a good data point for CO2, so we can fit the CO2 forcing on the temperature and refine the error bars. The error bars have shrunk significantly with time and all show the anthropogenic forcing of the 1900s.

The methods have held up to enormous scrutiny and attack over 20 years and strong anthropogenic CO2 forced warming is still the best explanation. In fact the overall idea has held up so well that even big oil companies who poured so much into attacking the theory have basically stopped arguing that anthropogenic CO2 increases have caused the observed warming, and they have either moved on to mitigation (in the case of BP) or the new argument that GW "ain't so bad" (Exxon-Mobil).

You keep contending these and similar questions are 'irrelevant.' I contend they are not only relevant but the answers are crucial if the science is as certain as you contend.

The question you posed immediately above is certainly relevant. The questions before that led to my volcano analogy (that you conveniently ignored) are irrelevant because they show fundamental misunderstanding about what anthropogenic GW theory claims.

 

[Mike Smith]

Sorry I missed replying on the volcano analogy. I agree with it.

Would you please point me to the year-by-year verification of Hansen's 1988 temperature forecast to which you refer? I didn't know one existed and I would like to see it.

 

[Robert Dewey]

Together, these two realities lead me to strongly believe that human contributions to global warming are real.

Ah yes, but that's the crux - belief.

...what would it take to convince you that humans are contributing to global warming?

If we are talking about a belief, then convincing isn't something that you should do. Yes, I am open to all possibilities because I can't personally rule out anthropogenic causes for global warming... but I won't try to convince others that one theory is any better than the next.

My main "beef" is that some people try to argue that anthropogenic global warming is indeed a fact rather than a belief... when it's nothing more than a theory.

 

[Kevin Scharfenberg]

Sorry I missed replying on the volcano analogy. I agree with it.

Would you please point me to the year-by-year verification of Hansen's 1988 temperature forecast to which you refer? I didn't know one existed and I would like to see it.

No problem Mike! The best verification is in Hansen, J., Mki. Sato, R. Ruedy, K. Lo, D.W. Lea, and M. Medina-Elizade, 2006: Global temperature change. Proc. Natl. Acad. Sci., 103, 14288-14293, doi:10.1073/pnas.0606291103, http://pubs.giss.nasa.gov/abstracts/2006/Hansen_etal_1.html . I'd also point out while it's a verification of his own work from 18 years before, he's pretty fair about pointing out the shortcomings of the original work.

 

[John Bowles]

Ah yes, but that's the crux - belief.

If we are talking about a belief, then convincing isn't something that you should do. Yes, I am open to all possibilities because I can't personally rule out anthropogenic causes for global warming... but I won't try to convince others that one theory is any better than the next.

My main "beef" is that some people try to argue that anthropogenic global warming is indeed a fact rather than a belief... when it's nothing more than a theory.

Shame, I'd expected people here to be above the silly "Just a theory!!!" stuff. Anyone with a basic knowledge of science knows that "theory" is the highest state an idea can aspire to.

99% of modern science deals in things that are "just a theory".

Of course, a theory isn't always correct. But try to use actual arguments and evidence, rather than the "just a theory" crap thrown around by people ignorant, often willfully, of how science works.

If someone argued that the solar system was geocentric - and there are people out there who seriously do, would you refuse to correct them because, well, one idea is as good as another, no matter what evidence there may be?

 

[Robert Dewey]

Of course, a theory isn't always correct. But try to use actual arguments and evidence, rather than the "just a theory" crap thrown around by people ignorant, often willfully, of how science works.

Mike is presenting a lot of facts. Those facts support what is called a theory. You might call it "crap", but I call it a theory

If science works the way I think it does, then there can be more than one theory per problem... right? Which theory do you choose when there are many with equally supportive facts?

I guess I'm not understanding your argument. You're saying that "theories" are a crap argument, yet you state that 99% of science deals with theories. Well, yes... and that's why I am open to supporting multiple theories per problem, and I hope you are too, John - especially when those theories are sound and have an equal amount of supporting evidence.

 

[Dan Robinson]

What bothers me about AGW is the rapid, total and dogmatic acceptance of a complex and relatively new theory that will have huge implications for public policy and personal cost for every individual. Scrutiny of something this serious should be expected.

I've said it before, but I'm not an anti-AGW crusader. I want to know the truth beyond a shadow of a doubt. But it bothers me that this new idea of AGW is suddenly here and has made inroads way too fast. If a meteor is going to wipe out earth and make us all flee to another planet, I want to see that meteor with my eyes, not just accept a theory that it might be there.

 

[Mike Smith]

Several times in discussions on AGW recently, I have criticized the practice of verifying GCM's based on (only) hindcasting. I have mentioned that there is a long history of hindcast-only tested models failing in the financial world. There is an article in today's "Wall Street Journal" that reinforces the futility of using only the past to forecast the future.

The question on everyone's mind is, when will the market hit bottom? Analysts who dissect market movements have many theories about how to pick the bottom. One that has been effective is to look for days of exceptionally heavy selling, followed by days of exceptionally heavy buying. The logic: When stocks are approaching the end of a decline, investors tend to be in a panic, and their sell orders dominate trading. Then, once the selling runs its course, bullish investors step in with heavy buy orders that dominate trading and, in turn, signal the beginning of a rally.

Lately, that combination of heavy selling followed by heavy buying is exactly what the market has seen -- on steroids.

"We have been getting these days at the rate of one every 3½ days, and that's just crazy," says Paul Desmond, president of research service Lowry's Reports in North Palm Beach, Fla., who has done extensive research on the subject. "We don't have anything like that anywhere in our history" of data, going back to 1933, he says.

There are "tried and true" models for forecasting the stock market: An inverted yield curve (i.e., when short term interest rates are higher than long term interest rates) = lower stock prices (supposedly). Decreasing dividend returns = lower prices, etc. These work great -- until they don't. The models seem to have failed to anticipate the recent market turmoil due to the mess in the subprime mortgage market.

Sometimes we meteorologists can be too inward looking. There are valid modeling analogies we can look at to see what we might learn. A lot of money has been spent creating stock market models based on "physics" or "the science of economics." One day, someone might create one with a great deal of skill. But, I'll be that model will have been tested in forecast, as well as hindcast, mode.

Mike

 

[David Wolfson]

The GCMs aren't verified only by hindcasting -- in fact they aren't validated (the more correct term, I think) mostly that way either. The GCMs are made up of many, many sub-models that are themselves scrtinized for validity and continually verified. A perfect case-in-point is the arctic summer ice cover discussed earlier in the thread. The sub-models have apparently not caught this, and are not verifying well at the moment. You can be sure that the modelers are scrambling on this one.

So... does this diminish the validity of the GCM? Sure, and that's why it's so important to get good data, develop good causal physical relations among the data, and improve the models.

Socioeconomic models are very different animals because they deal with individual and group human behavior acting in a hugely complicated external effects space.

 

[John Bowles]

Mike is presenting a lot of facts. Those facts support what is called a theory. You might call it "crap", but I call it a theory

If science works the way I think it does, then there can be more than one theory per problem... right? Which theory do you choose when there are many with equally supportive facts?

I guess I'm not understanding your argument. You're saying that "theories" are a crap argument, yet you state that 99% of science deals with theories. Well, yes... and that's why I am open to supporting multiple theories per problem, and I hope you are too, John - especially when those theories are sound and have an equal amount of supporting evidence.

Whenever someone says "its just a theory", they are almost always trying to claim its just something someone made up. If you didn't mean it that way, fine, but thats the way everyone else who says it means it.

"Its just a theory" is used to avoid arguing about the actual evidence for or against anything, instead simply dismissing it.

 

[John Farley]

If science works the way I think it does, then there can be more than one theory per problem... right? Which theory do you choose when there are many with equally supportive facts?

When the facts are equally supportive of several different theories, it is hard to choose. But my point is that the facts are more consistent with the theory of AGW than of no AGW. So in this case you go with the theory of AGW because it has more facts (e.g. temperature trends consistent with what the theory and models predict) supporting it than opposing theories.

 

[Mike Smith]

John,

Your point is well taken, but I'd ask you to consider the following with an open mind:

The trend in temperatures was strongly up from around 1750 to 1940. In fact, because of the mid-20th Century cooling, current temperatures have yet to catch up to the 1750-1940 long-term trend line.

There are peer-reviewed papers (I referenced them in a thread several months ago) that say the sun, from around 1980 to about 2000, was burning hotter than in other years. Not being an astronomer, I don't know whether those papers are correct, but they are peer-reviewed.

Given the supposedly warmer sun and given that temperatures have not caught up to the longer term term trend line those two relatively simple natural explanations could explain much of the warming we have seen. No one is saying greenhouse gasses do not affect temperatures, the question is how much.

How much warming has occurred?

One does not have to believe in "conspiracies" to believe that the USHCN has a warm bias starting in the early- to mid-1990s when the MMTS instruments were installed. This bias has not been corrected for in the U.S. temperature record. Note: For those unfamiliar with this issue, this is different from the "Y2K" problem that was corrected for in August. There are numerous instrumental problems in other nations that have been identified.

When Hansen says that Y2K in the U.S. (not to mention the uncorrected for MMTS bias) plus problems with the data for Africa and South America "has only a tiny effect on the global temperature change" -- one starts wondering where Hansen/IPCC is measuring?

Considering Landsea's work on the subject of "missing hurricanes" do we really believe the world's ocean temperatures were uniformly and accurately measured in, say, 1899? The fact that the oceans are supposedly warmer than 100 years ago is not particularly convincing to me because there were vast, unmeasured areas of the ocean.

Comparing today's satellite sea surface temperature data with late 19th century measurements, to me, is not particularly compelling.

Finally, I can show you wildly differing presentations of U.S. temperatures in the 1930's. I have one screen capture from the great GC debate of the 1970's that came from NCAR showing the 30's were warmer than is being depicted today. It seems that as time progresses the 1930's get cooler in the GISS database. Prior to last Friday, Hansen refused to release his code which would shed light on this question.

All of these are legitimate scientific issues.

I have said -- publically and privately many times -- I am perfectly willing to believe the AGW hypothesis when the science is there. For those of us expessing doubt, it is not because we are deniers or ignorant. It is because there are legitimate questions that, from our perspective, have not been sufficiently addressed.

I do not wish to start another round of discussion. I simply am requesting some professional courtesy. Lets stop the name calling, the accusations of conspiracies, etc., and try to convince each other using scientific data.

Mike

 

[Mike Smith]

Finally, I can show you wildly differing presentations of U.S. temperatures in the 1930's. I have one screen capture from the great GC debate of the 1970's that came from NCAR showing the 30's were warmer than is being depicted today. It seems that as time progresses the 1930's get cooler in the GISS database.

We, apparently, have yet another change to temperatures in the 1930's and, not surprisingly, the effect is to make the 1930's cooler than today. Please see: www.climateaudit.org/?p=2077#comments

By the way ROW = "the rest of the world."