Is Al Gore's Presentation of Global Warming in An Inconvenient Truth Accurate?

[mheslep]

... As of now, I think the CO2 content is something like 375 ppm, and this has increased by more than 100 ppm in the last century. Even in the last 10 years, there has been a noticeable increase. It depends of course when you put the counter to 0, and what data you find reliable, but 3% would represent only 10ppm, which is certainly not the total observed CO2 increase.

Its commonly known that measurements have been taken to tell how much of the C02 increase is man made, that is due to the burning of fossil fuels, and how much is due to natural causes, due to out gassing from warming oceans for instance. In this 'last 10 years' case are you sure the increase again has been checked for man-made vs natural? Yes or no, I often wonder in general when I see the CO2 updates quoted whether or not they are quickly grabbed from a raw partial pressure measurement or the required discriminator (some isotope measurement I assume?). In the last 10 yrs its obviously warmed so we'd expect natural increases in CO2 even if man made vanished.

 

[kamerling]

Strange, C02 levels were much, much higher 100,000 years ago, when there was a mile high layer of ice covering half of North America. Who do the AGW theorists blame that one on?

II think you are misinformed here. I don't think anyone believes CO2 was ever significantly above the preindustrial levels during any ice age in the last few million years. see here for example:

http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_co2.html"

There's a strong positive correlation between CO2 and temperature during the last 400,000 years at least, however with CO2 lagging up to 1000 years after the temperatures. The CO2
is probably produced when the ocean is warmer and taken up when it gets colder. This is believed to increase the severity of ice ages.

 

[kamerling]

Its commonly known that measurements have been taken to tell how much of the C02 increase is man made, that is due to the burning of fossil fuels, and how much is due to natural causes, due to out gassing from warming oceans for instance. In this 'last 10 years' case are you sure the increase again has been checked for man-made vs natural? Yes or no, I often wonder in general when I see the CO2 updates quoted whether or not they are quickly grabbed from a raw partial pressure measurement or the required discriminator (some isotope measurement I assume?). In the last 10 yrs its obviously warmed so we'd expect natural increases in CO2 even if man made vanished.

We produce more CO2 than the increase in the atmosphere, so the ocean is still taking it up .

 

[Andre]

There's a strong positive correlation between CO2 and temperature during the last 400,000 years at least, however with CO2 lagging up to 1000 years after the temperatures. The CO2
is probably produced when the ocean is warmer and taken up when it gets colder. This is believed to increase the severity of ice ages.

Well, if you scrutinize the details a bit, it may seem a bit different:

https://www.physicsforums.com/showthread.php?t=162192

 

[ecofan]

In the last 10 yrs its obviously warmed so we'd expect natural increases in CO2 even if man made vanished.

Actually, temperatures have been nominally flat for the past 8 years, except for this winter, which has been unseasonably cool.

 

[ecofan]

This just in:

Excerpt: Some 3,000 scientific robots that are plying the ocean have sent home a puzzling message. These diving instruments suggest that the oceans have not warmed up at all over the past four or five years. That could mean global warming has taken a breather. Or it could mean scientists aren't quite understanding what their robots are telling them. The buoys can dive 3,000 feet down and measure ocean temperature. Since the system was fully deployed in 2003, it has recorded no warming of the global oceans. "There has been a very slight cooling, but not anything really significant," Willis says. So the buildup of heat on Earth may be on a brief hiatus. "Global warming doesn't mean every year will be warmer than the last. And it may be that we are in a period of less rapid warming."

Interesting, since the story comes from the liberal NPR . Rest of article http://www.npr.org/templates/story/story.php?storyId=88520025"

 

[mheslep]

Actually, temperatures have been nominally flat for the past 8 years, except for this winter, which has been unseasonably cool.

Eh, unusually?

 

[kamerling]

Actually, temperatures have been nominally flat for the past 8 years, except for this winter, which has been unseasonably cool.

While it may be true that the temperatures have been flat for the past 8 years, because of the increases in previous years and the slow heat uptake of the ocean, you would still expect the ocean to become warmer. If it does not there must be something else going on.

 

[Gokul43201]

Actually, temperatures have been nominally flat for the past 8 years, except for this winter, which has been unseasonably cool.

I just looked at the recent data from NASA: http://data.giss.nasa.gov/gistemp/

I then compared the mean temperature anomaly during the period 1999 through 2001 (mean = +0.4833K) with that during the period 2005 through 2007 (mean anomaly = +0.7133K). I get an increase in mean temperature of 5.7K/Cent, which I think is actually significantly larger than the long-time average slope in the last couple decades.

How do you say the temperatures have been flat?

 

[vanesch]

Its commonly known that measurements have been taken to tell how much of the C02 increase is man made, that is due to the burning of fossil fuels, and how much is due to natural causes, due to out gassing from warming oceans for instance. In this 'last 10 years' case are you sure the increase again has been checked for man-made vs natural?

I wasn't talking about what was the origin of the CO2 (human or natural), nor whether it gave rise to any warming (or whether it was caused by any warming); just the observation that the amount of CO2 in the atmosphere did rise for more that 3% in the last century.

 

[vanesch]

In any case, when we see already here how involved the debate is, how easy one gets convinced by an erroneous argument, how complicated the interpretation is of the data, I wonder how a poor judge is going to "know the truth" in just a few hearings!

 

[mheslep]

I wasn't talking about what was the origin of the CO2 (human or natural), nor whether it gave rise to any warming (or whether it was caused by any warming); just the observation that the amount of CO2 in the atmosphere did rise for more that 3% in the last century.

Well if we're not interested in whether or not the CO2 source is natural then the whole subject is moot since we can't do anything about the source. (Other than for purposes of scientific curiosity).

 

[vanesch]

Well if we're not interested in whether or not the CO2 source is natural then the whole subject is moot since we can't do anything about the source. (Other than for purposes of scientific curiosity).

The discussions on the web pages of "debunkers of AGW" were trying to establish that the CO2 concentration has no influence at all on the thermal balance in the atmosphere ; one by trying to demonstrate that CO2 didn't absorb anything (or almost so), the other by showing that CO2 already absorbed everything it could, and that adding more to the atmosphere was not going to change the radiation balance.

In as much as I regret not seeing a detailed description of the physical processes taken into account in MODTRAN, I would take it as a more reliable radiation transport calculation, which shows us that a doubling of the CO2 content is responsible for a "radiative forcing" which is of the order of a to a few watts per square meter.

I don't think that trying to prove that CO2 doesn't do anything in the radiative balance of the atmosphere is going to work out, honestly. And from the moment that it does *something*, then everything comes down to careful calculation. We are talking here of a 1% effect. This means you have to be accurate on at least the promille level, and then you have to take into account all kinds of small details.

EDIT: BTW, if there is a positive feedback mechanism on the CO2 (for instance, by heating the oceans, they give off more CO2 etc...) and if this mechanism is significant, then in fact MOST of the CO2 increase we see in the the atmosphere is NOT going to be from human origin, but rather from this mechanism. If this is true, then we are already in deep doodoo because even if we totally stop our emissions today, we haven't gotten any handle on MOST of the increase.

 

[ecofan]

I don't think anyone is trying to say CO2 doesn't do anything... certainly there is BB absorption by CO2 and CH4. But the contribution appears to be relatively small compared to H2O and the whole impossibly complex cloud cover situation.

Frankly, I think we've been lucky that the past century or two has been nice and warm - we should be enjoying this interglacial period instead of trying to kill the warming trend with carbon offsets and other nonsense.

I see the latest sat photos show the Arctic Ice Cap now up to about 14 million square kilometers... even larger and reportedly thicker than the winter of 06-07, before the "catastrophic" breakup of the summer of '07 which caused Al Gore to predict the cap will be gone in 5 years.

I watched The Day After Tomorrow on DVD last week. Temperature dropped to minus 170 so fast the oil lines in some helicopters froze while ferrying the royal family somewhere. Seems there's a good side to all this after all.

 

[vanesch]

I don't think anyone is trying to say CO2 doesn't do anything... certainly there is BB absorption by CO2 and CH4. But the contribution appears to be relatively small compared to H2O and the whole impossibly complex cloud cover situation.

The way I understand this, AGW can be sliced in several components:
- the forcing by CO2, and the radiative effects of CO2.
- the origin of CO2, and the carbon cycle
- the climate effect of the radiative forcing, including a lot of feedback mechanisms
- the predicted evolution over a century of all of this, including human behaviour

I would say that in this list, we go from the pretty well established to the totally speculative, and the problem is that what matters is not whether certain effects exist, but rather, how numerically accurate all of this is. Because in the end, it makes a difference if we will warm or cool, and whether it will be 1 degree, or 5 degrees, or 25 degrees.

I'm trying to understand the argumentation from each side. I don't think anything has been shown for sure, either way. It is a pity that the debate is now so polarized, that one cannot have a open, scientific, inquiring discussion. I personally *would like to know* what is scientifically established, what is plausible, what is suggested, what are possible explanations, and what is totally open to speculation.

 

[ecofan]

Here's one clear fact. I'm sick of this current cold, miserable winter in New England. Bring me some more global warming!

 

[Bystander]

(snip)In as much as I regret not seeing a detailed description of the physical processes taken into account in MODTRAN, I would take it as a more reliable radiation transport calculation, which shows us that a doubling of the CO2 content is responsible for a "radiative forcing" which is of the order of a to a few watts per square meter.(snip)

You can test it; compare the "radiative forcing" over the past century to the effects claimed to date. Couple orders of magnitude error in the energy balance over that time is sufficient grounds to relegate it to "file 13."

 

[vanesch]

You can test it; compare the "radiative forcing" over the past century to the effects claimed to date.

It is not so easy, because radiative forcing by itself is hardly measurable, if it is measurable at all. In as much as I understand it, radiative forcing is an abstract quantity, which gives you the difference between the downward radiation power with, and without the "effect under study", at a certain height (tropopause, but you can change it), but ALL ELSE EQUAL (except - if I understand well - a possible change in temperature of the highest layers to reach equilibrium).

The way I see it - I can be wrong, but it is the best I can make out of the definitions in the IPCC report which are pretty vague - is that if you consider the down-going radiation power to be a function of all kinds of parameters (CO2-concentration, water concentration, temperature profile, soil type, ocean content, water temp, vegetation, thickness of ice caps, age of the captain...), then the radiative forcing is a PARTIAL DERIVATIVE wrt CO2-concentration (times this change in concentration).

At least, that's how I understand it, but I'm not 100% sure that that is what is meant.

If that's true, you cannot really measure it (but you can calculate it in a model), because there's no way in which you can keep all the other parameters fixed in the real world, where OTHER phenomena will link all the parameters.

 

[drankin]

All-in-all, it doesn't seem to me that pollution itself greatly impacts the climate. The climate takes care of itself regardless of what earthly inhabitants do. A testament to the resilience of the planet as a whole. We could make the atmosphere uninhabitable to life itself but I don't believe we make a dent in comparison to what the sun subjects the atmosphere to every hour. Not even throwing in Earth's own geological contribution. In a hundred years after mankind choked itself out of existence, the Earth would just clean itself up and continue on. We just aren't that big a deal to the "global climate", IMO. Our attention should be focused on cleaning up our environment so we can live in it. Not prophecying gloom and doom as if we are actually changing the climate.

 

[vanesch]

In a hundred years after mankind choked itself out of existence, the Earth would just clean itself up and continue on. We just aren't that big a deal to the "global climate", IMO. Our attention should be focused on cleaning up our environment so we can live in it. Not prophecying gloom and doom as if we are actually changing the climate.

Uh, I don't think that any reasonable human being cares a iota of what might happen to planet Earth and its biosphere after humanity has disappeared (or are there ? ). I think that the whole idea is that we might regret in the *near future* that the quality of life degraded too much.

Personally, I don't even care for the fate of humanity in the far future - after all, is it worse that people suffer 2000 years from now in the future, or in the past ? But I do care about the near future, for myself, and for my close offspring and so on. It would annoy me if they suffered while we could have avoided it. But there are some people who seem to care about the destiny of humanity on the long term. I have difficulties understanding them, but ok...

So all this is about the *near future* and about *us*, say, 100 years or 200 years. Are we going to mess up for our old days, or for the old days of our kids and friends ?

Really, whether we mess up for the supersonic cockroaches that will come after humanity, is there really anybody who cares ?

 

[Gokul43201]

All-in-all, it doesn't seem to me that pollution itself greatly impacts the climate. The climate takes care of itself regardless of what earthly inhabitants do. A testament to the resilience of the planet as a whole. We could make the atmosphere uninhabitable to life itself but I don't believe we make a dent in comparison to what the sun subjects the atmosphere to every hour. Not even throwing in Earth's own geological contribution.

The concept of a nuclear winter is also a figment of fantasy then, I guess.

 

[mheslep]

The concept of a nuclear winter is also a figment of fantasy then, I guess.

It was certainly bad science. Largely discredited.

 

[Gokul43201]

It was certainly bad science. Largely discredited.

Wow! I didn't know this. I even thought there was a cooling signal measured in the Middle East following the burning of oil wells in Kuwait. Heck, I've thought there were cooling signals measured after every big volcanic eruption. I look forward to reading any relevant geophysical analysis that predicts the likely (lack of) effect on climate by any human or volcanic activity. (But so as not to derail this thread any further than has already happened, I've started a new thread in the Earth Sciences subforum to address this question.)

Edit: I just realized that it wasn't you (mheslep) that authored the philosophical/theosophical musing of post #109. So I won't ask you to substantiate any of the broader assertions - that is for drankin to do.

 

[Bystander]

It is not so easy, because radiative forcing by itself is hardly measurable, if it is measurable at all.(snip)

"Few watts per square meter" ain't measurable? Modtran is being used to model the radiation balance (or imbalance for the greenhousers), and says absorbance exceeds emittance by something on the order of a watt per square meter? Heat capacity of 10 tons of air per square meter, plus 2-3 meters of earth/rock times 0.3, plus 10 meters of sea water times 0.7 is 40 MJ/K, or ~K/a at one watt per meter squared.

 

[vanesch]

"Few watts per square meter" ain't measurable?

I didn't mean it in the sense of "negligible", but rather: not a measurable quantity as such because of the conditions in its definition: "all else equal". If you disturb the radiation balance, for instance, it is going to be difficult to keep the temperature constant.

More mathematically, you can only measure the total differential, and not the partial derivative.

 

[Gokul43201]

or ~K/a at one watt per meter squared

What's "K/a"?

 

[drankin]

Wow! I didn't know this. I even thought there was a cooling signal measured in the Middle East following the burning of oil wells in Kuwait. Heck, I've thought there were cooling signals measured after every big volcanic eruption. I look forward to reading any relevant geophysical analysis that predicts the likely (lack of) effect on climate by any human or volcanic activity. (But so as not to derail this thread any further than has already happened, I've started a new thread in the Earth Sciences subforum to address this question.)

Edit: I just realized that it wasn't you (mheslep) that authored the philosophical/theosophical musing of post #109. So I won't ask you to substantiate any of the broader assertions - that is for drankin to do.

Gokul, have these human activities altered the "global climate"? That is the point we are discussing. Sure, there are temporary local measurements due to burning oil wells and volcanic eruptions. It's the human impact we are trying to ascertain. Where is this evidence? As far as I'm concerned everyone here is posting their flavor of a "philosophical/theosophical musing".

 

[Gokul43201]

Gokul, have these human activities altered the "global climate"? That is the point we are discussing. Sure, there are temporary local measurements due to burning oil wells and volcanic eruptions. It's the human impact we are trying to ascertain. Where is this evidence?

I haven't seen any assertion in this thread that human activities have altered global climate, other than ecofan and vanesch concurring that atmospheric CO2 must play some role in radiative forcing, the extent of which is under debate. On the other hand, you've just made a very strong assertion that neither human nor geological activity makes a dent in global climate, without any substantiation.

As far as I'm concerned everyone here is posting their flavor of a "philosophical/theosophical musing".

Find me another post in this thread that does this.

 

[drankin]

You must have misread my post, I didn't say that geological activity doesn't make a dent. I concede that it probably wasn't clear what I meant (posting at 1:43am). I was comparing the human impact versus solar, "Not even throwing in Earth's own geological contribution.".

I don't believe humans are changing the global climate. I have no more or less evidence of that than anyone else. The difference is that I'm not throwing in a bunch of sketchy theory to substantiate my point. I don't have to, it is the alarmists who have to provide the evidence that the sky is falling.

 

[vanesch]

I don't believe humans are changing the global climate. I have no more or less evidence of that than anyone else. The difference is that I'm not throwing in a bunch of sketchy theory to substantiate my point. I don't have to, it is the alarmists who have to provide the evidence that the sky is falling.

I don't see why the statement "humans cannot have any substantial influence on climate" would be the "default wisdom" statement, which DOESN'T need any scientific argumentation, but that the opposite statement "humans can have a serious influence on climate" would need a proof. BOTH are falsifiable statements (in the long run), so both need, in order for one to take them as "scientifically established" scientific proof in one way or another.

I don't see what the first statement has of "more evident" than the second. The statement "I don't BELIEVE humans are changing the global climate" is just as much a *belief* without foundation as the statement "I BELIEVE humans are changing global climate".

I don't believe anything, either way, but if anything, there are *indications* or *suggestions* of a potential human influence on climate which I find - until someone convinces me of the opposite - not yet sufficiently strong to make me BELIEVE anything, but I take notice of the suggestions.