brazil84's Global Warming Thread

Great Debates
61

I graduated in 1985 with a degree in meteorology, and global warming (known as the greenhouse effect at the time) was discussed thouroughly. It has been a scientific pursuit for decades before Al Gore came along and introduced it to the public at large. There is no “liberal agenda” that comes with global warming, it is just science. Unfortunately for some, it is a global issue and it requires international cooperation and agreement to address it. The U.S. can’t make it go away all by itself, and the rest of the world can’t do it without the U.S.

The fact that people of a certain political bent really hate the U.N. and international cooperation doesn’t mean squat, unfortunately. Global issues require global solutions. This isn’t “Independance Day”.

I find it fascinating that this issue has become politically charged. Somebody is going to be found dead wrong, and there will be a steepo political price to be paid by the loser.

62

Worse, it’s become a fashion statement. “Prevent global warming” over here has become the equivalent of “Have a Nice Day.” They put it on a bumper sticker or T-shirt, then don’t think about it again. Wearing that T-shirt means they are doing their bit and so don’t have to do anything else. Sort of like those rock concerts where the audience thinks they’ve done enough simply by attending.

63

I doubt it. The IPCC will say “Hey, we were only 90% sure.” The NAS will say “Hey, we said the projections were tentative.” Michael Mann will still have tenure. James Hansen will still have a job. AGW supporters will remind us that they were only pushing for the “precautionary principle.” The socialist/green types will seek out the next cause dujour. Life will go on, but mankind won’t learn anything. The next generation will be taken in by another hoax/mania/moral panic.

64

This is much too close to a personal insult. Back off.

And he has reported you for shucking and jiving and asking for citations that have already been provided, so making a public issue that you have reported his post looks suspiciously like you are simply trying to game the thread by dragging the staff in on your side.

Have the debate or ignore your opponent as not worth the effort, but leave the personal observations out of this thread.

[ /Moderating ]

65

This isn’t even really close to the right calculation to do, besides which I have no idea where you get your 5% number as that is lower than any other estimates, even if you look only at the “bare effect” (i.e., imagine taking the CO2 out without then dealing with the feedback effect that this cooling will have on lowering water vapor). Also, it is well-understood that in the range we are in, the warming of CO2 is logarithmic in its concentration.

Again, this is irrelevant. It is arguing against a strawman, namely that CO2 is the only factor responsible for the global temperature variations over the period of the instrumental record. Noone believes that so it is silly to argue against it. The correct way to do the calculation is to try to include one’s best estimates for the natural and anthropogenic forcings and see how well such modeling can reproduce the temperature record. Results of such an exercise are shown here.

66

Lol. I got the 5% number from aptronym. It’s his or her calculation. And I agree that it’s not right – I was simply using his or her “linear” assumption.

Again, I’m arguing against aptronym. He or she really claimed that a simple calculation involving CO2 can and does account for observed warming. And that models are necessary only to confirm this result.

Sadly, it’s not a strawman that I’m arguing against. But feel free to tell aptronym that his or her argument is silly. I won’t stop you.

67

Most of this thread illustrates perfectly why I’m pessimistic about our chances to halt or reverse global warming. Everyone involved will still be busy bitch-slapping each other right up to the very moment the Earth decides she’s had enough and creates a backlash.

68

What unmitigated hogwash! There is no rule about negative feedback loops dominating positive ones. In certain specific situations, e.g., where a positive feedback would lead to a violation of some fundamental physical law like conservation of energy then one can bet that it won’t be there. But positive feedbacks are prevalent in the real world…in fact they are responsible for all of the instabilities that lead to “pattern formation”, which describes everything ranging from dendritic growth (e.g., snowflakes) to sand dunes to how zebras get their stripes.

And, the claim that positive feedbacks can’t exist because they will necessarily lead to instability is hogwash too. It is true that a sufficiently strong positive feedback will lead to instability. However, a weaker one will simply magnify the effect. The important question to ask in determining which of these occurs is if the sort of series you get when you add up the bare effect, the feedback on the effect, the feedback on the feedback, and so on is a converging series or a diverging series.

For example, in the current case of the water vapor feedback on the CO2 greenhouse effect, let’s suppose (using numbers believed to be at least roughly correct) that each degree of warming due to an increase of CO2 then leads to an increase in water vapor that causes an additional 1/2 degree of warming. Then, this warming will itself induce an additional increase in water vapor that causes an additional 1/4 degree of warming, and this then another 1/8 degree of warming. This is a convergent series that has a value of 2, which means that the result of this hypothetical (but realistic) water vapor feedback is not a “runaway” effect but simply a multiplication of the warming due to the “bare effect” of the additional CO2 by a factor of 2.

69

Well, what you are dealing with is a few diehards here. I used to say that the skeptics here were akin to Exxon (and way way behind BP and Shell and Ford) in accepting the science. Now, with Exxon’s recent public statements on climate change, I have to say that they are even behind Exxon…or at least Exxon’s public stance. (Exxon has, at least up until recently, still been giving lots of money to various groups who do their best to muddy the waters about climate change.)

As more and more of the business community accepts reality, the “skeptics” are sort of being left behind.

70

Those of us who have some familiarity with the issues being discussed know exactly who is getting bitch slapped, and it isn’t even arguable. Unfortuantely, 99% of the population don’t really have any grasp of the subject matter so they are susceptible to bad (faith) arguments.

71

Sam: I think these statements confuse a couple of different levels of discussion. It is true that all knowledge in science is provisional and no scientific debate is truly ever closed. This stems from the fact that science is inductive and thus (despite Quartz’s constant misuse of the term…argh!!!) there is no such thing as proving a scientific theory. You prove theorems in mathematics…You don’t prove theories in science; you simply gather evidence to the point that it becomes increasingly untenable to believe that the theory is “incorrect” (where the idea of correctness is used in a sort of utilitarian sense here, i.e., where I would say Newton’s Laws are still correct in their domain even though Einstein and quantum mechanics have shown us that there are realms where they do not apply).

So, I absolutely agree that on the scientific level, the scientific debate over global warming is not closed (nor is the one about gravity…and in fact we still don’t understand how to reconcile gravity and quantum physics).

However, in a practical sense, when science is used to inform public policy, we can’t wait until we have 100% scientific certainty before moving on to the discussion of policy options…because we would be waiting until the end of time. This is why it is important to have institutions in place that provide an assessment of the science and, while perhaps not telling us directly what to do, do lay out and discuss the various policy options and their effects. This is in fact exactly what the IPCC does, chartered by the nations of the world through the U.N., in the case of climate change. And, it is what the U.S. National Academy of Sciences does for the U.S. federal government on a whole variety of scientific issues.

Are the conclusions of such organizations infallible? No. However, they represent the best way we know how to distill scientific knowledge for the public and policymakers. If we refuse to accept their conclusions when we don’t really like them, then we basically set up a situation where science is no longer used to inform policy…and the whole situation just becomes a political free-for-all. I think this is the sense in which people say things like “the debate is over” and “the science is settled”. They’re not saying that scientists are no longer supposed to discuss it but simply that it is not tenable to say that there is not now very strong scientific evidence in one direction.

As for your specific links, the ones by Lord Monckton and Senator Inhofe & co. [now in the minority (thankfully!!!) on the Senate Environmental and Public Works Committee] are probably not worth the time to dissect. The paper that you quote from the press release of is indeed peer-reviewed although one must keep in mind that the press release is not. If you look at the abstract of that paper (which is all I could get hold of so far), you will see that it sounds a lot less strong than the press release (perhaps not surprising given the well-known views of at least 3 of the 4 authors of that paper). And, as GIGObuster noted, RealClimate has already weighed in with some opinions on where they think it is wrong.

At any rate, it is important to realize that, while peer-review is a good minimum “bar”, the fact that you can find a peer-reviewed paper to support a particular point of view in an active area of science where probably thousands of papers are published each year, does not mean a whole lot. And, it is important to remember that no such paper alone can overturn all of the evidence that has been amassed in favor of AGW. For example, while that paper on cirrus clouds looks interesting, there are still lots of questions to be answered. The author himself notes one of them, i.e., whether what he found on this small scale really operates on the scale of interest. However, there are many others including the correctness of the observations and how one can reconcile such a stabilizing effect with our current understanding of past climate changes. For example, any theory that invokes strong stabilizing effects in the climate system has to explain how we could still get the sort of dramatic glacial - interglacial cycles over the past few million years given the perturbations to the climate system that were acting at those times. So, while it may make for interesting scientific discussions in the field, I see no reason why the general public or policymakers should be “stopping the presses” or anything of the sort.

72

Actually, after reading the press release again, I have decided that my statements about it were too weak for me to let it drop without further comment. That press release is garbage and basically represents “spin” that I can’t imagine is possibly in the peer-reviewed paper (and is certainly not the abstract). And, it’s from someone who has a well-known history of doing this sort of thing (i.e., putting his own spin on papers from the peer-reviewed literature, although usually it has been with other authors’ papers rather than one of his own): Fred Singer, along with co-author Dennis Avery, recently used the peer-reviewed scientific literature to compile a list of “more than 500 scientists [who] have published evidence refuting at least one element of current man-made global warming scares”, but they defined this so broadly that their list included Michael Mann as well as two other regular contributors to the RealClimate.org website! When I looked at the actual papers that some of these authors had written that got them included on the list, it became clear just how pathetic that list was. (See my posts #51, 54, 59 in this thread.)

I’d love to see them actually try to back up the claim that “[These results] are supported by the results of the US-sponsored Climate Change Science Program (CCSP).” As far as I know, the Climate Change Science Program discussed the issues that the papers deal with in this report, which I don’t think reached conclusions anything like those of that paper, and certainly nothing resembling in any way whatsoever the claims in the press release.

73

That’s not exactly the claim. The claim is that negative feedbacks are much more common and that stable systems are generally dominated by negative feedbacks as opposed to positive feedbacks.

Perhaps, but let me ask you this:

As far as I can tell, it’s widely accepted that in the past, there have been numerous periods of rising temperature followed by rising CO2 levels, followed by decreasing temperature, followed by decreasing CO2 levels. What caused the temperatures to decrease?

74

As I noted, I know of no such rule to this effect.

Milankovitch cycles, which change the distribution of (although barely or not at all the total amount of) sunlight hitting the earth.

75

That doesn’t mean that no such rule exists. The person who made that observation claims to have some experience with system control.

Interesting, so you believe that the effects of a change in sunlight distrubution was enough to dominate the CO2/warming loop that has been hypthesized?

76

That doesn’t mean he’s right. It’s a new idea to me as well - I’ve always thought that the default assumption was a model with no feedback loops, and the feedback is included only when it’s identified. Has he published his “rule?”

In the absence of changes in the CO2 concentration, of course solar cycles dominate the system.

Even today, there are not insignificant changes to climate driven by solar cycles. Of the 0.6 degrees warming observed over the last 100 years, approximately 0.2 degrees is attributed to solar cycles and fluctuations. The fact that a majority of global warming is attributed to CO2 increases doesn’t mean that you ignore every other driver.

77

Of course not. It doesn’t mean he’s wrong either. It seems fairly common sense to me, though.

But the examples I gave apparently took place in the face of significant changes in CO2 concentration. No?

78

I don’t know, because you didn’t give any specific examples. You just posited a time that temperature rose and CO2 rose slightly after it. Do you have specific dates in mind?

79

Wow…That’s a strong argument. Someone, god knows who, on the web said something that contradicts all the understanding of actual scientists in the field…but since it makes sense to you, who can argue with it?

Okay…Let me explain the Milankovitch picture to you. The cycles cause a change in distribution of sunlight hitting the earth which causes ice sheets to either start to expand (at the end of an interglacial) or contract (at the end of an ice age). [The reason a change in the distribution of sunlight causes this, for example, is that the two hemispheres are not equivalent because of the different distribution of land mass.] Now, the net radiative forcing due directly to the change in the distribution of sunlight is almost nil since it is just a change in distribution not total amount of sunlight hitting the earth. However, the resulting growth or contraction of ice sheets produces a change in radiative forcing due to the higher albedo (reflectance) of the ice.

As this happens, by processes still not completely understood, but likely having to do with the overturning of the oceans, CO2 is released from (at the end of an ice age) or absorbed by (at the end of an interglacial) the oceans and, to a lesser extent, possibly the biosphere too. This CO2 then acts as a positive feedback causing additional warming (when it goes up at the end of an ice age) or cooling (when it goes down at the end of an interglacial). The CO2 also seems necessary to explain how the two hemispheres’ climate changes pretty much in synch rather than having a sea-sawing effect instead. The best estimate is that the CO2 contributes about 1/3 of the warming at the end of an ice age (with methane adding a little bit more on to this…bringing the total effect of greenhouse gases up to close to 1/2).

Now, you might want to say, “Well, is the CO2 really necessary to explain the process?” As I noted above, it does seem to be necessary to synchronize the hemispheres. However, even more importantly, assuming the CO2 doesn’t contribute at all really doesn’t change your conclusion…It just leads to a contradiction. The reason is that the radiative forcing due to the change in CO2 concentration is accurately know. The change in radiative forcing due to the albedo effect can be estimated pretty well also. So, by looking at the global temperature change and dividing by the total radiative forcings, one can derive the climate sensitivity…i.e., the number of deg C the climate tends to change in response to a given change in radiative forcing.

Again, since we know the radiative forcing due to a given change in CO2, this then allows us to estimate the sensitivity of the climate to changes in CO2…and the result is an estimate of about 3 C for a doubling of CO2. Since the CO2 contributes to the forcings, just ignoring the effect of it when doing the above calculation only makes the climate sensitivity larger (because now you have the same temperature change but a lower estimate of the total radiative forcing that induced it)…and it also is not self-consistent since the relative magnitudes of the radiative forcings for the CO2 change and the albedo change suggest that the CO2 should be contributing about 1/3 of the change.

The only way to really get around this calculation is to propose that there is some very large forcing that we are missing. But, again, it has to be very large in order in order to explain the resulting temperature change between ice age and interglacial with a low climate sensitivity. (I suppose another way might be to try to argue that the climate sensitivity is highly nonlinear so that it is large between the glacial and interglacial but suddenly gets very small as you start to get temperatures above the interglacial. Of course, you would need some sort of picture about why this is the case…and it may be hard to explain the somewhat warmer interglacials that have been seen…e.g., the one previous to this one.)

80

Approximately 125,000 years ago; 250,000 years ago; 350,000 years ago; and 400,000 years ago.

See here:

http://www.climate-skeptic.com/2007/09/chapter-4-skept.html

Under the heading “The long view”