I’ll bite the bullet and say global warming is the perfect example here. It’s pretty clear to me that many people hold their positions on this issue—pro and contra—for political/social reasons rather than evidential ones.
There seems to be plenty of motivated arguing on both sides. But even though climate science is complicated the basic mechanism for CO2 raising temperatures is really simple and well supported by basic science. No one is disputing CO2′s absorption spectrum (that I know of). It’s possible that CO2 might not have any such effect on aggregate in a complicated system, but that would be quite remarkable and I don’t think any mechanism has been proposed (other than that global warming is miraculously balancing out a coming ice age).
My litmus test for whether someone even has the basic knowledge that might entitle them to the opinion that anthropogenic climate change isn’t happening is:
“All other things being equal, does adding CO2 to the atmosphere make the world warmer?”
The answer is of course “yes.” Now, if a climate change non-skeptic answers “yes” the follow up question to see if they are entitled to their opinion that anthropogenic climate change is happening: “How could a climate change skeptic answer ‘yes’ to that question?” The correct answer to that is left as an exercise for the reader.
Yes, but the behavior of one component of the system doesn’t necessarily determine the behavior of the system as a whole. It’s the responsibility of those who propose an anthropogenic climate change to prove that it’s happening, not the other way round.
Most of the actual scientific debate seems to be centered around the reliability of the temperature record (and of different proxies) and of climate models (I consider it very likely that the skeptics are right on many of these issues), not around the question whether an anthropogenic climate change of some level is happening at all. At least I’m not aware of any climate scientist making the argument that no anthropogenic warming effect could possibly exist due to X (where X is some [proposed] physical reality, not something of the sort “that would be human hubris”).
The closest thing I could find on that page and the the most promising looking links was the water vapor argument (which is more of an argument that AGW should be smaller than expected rather than non-existent) and he apparently doesn’t subscribe to that anymore. Other than that he seems content to cast doubts and make accusations against the other side. If he has a new X, is there any good summary anywhere?
Just out of interest, what would have been the correct answer to the test (rot13 if you don’t want to spoil it)?
The position of “sane” climate skeptics appears to be that rising CO2 levels’ effects on temperature will be dampened by other regulatory causal effects; the evidence for the existence of such regulatory feedback is the overall stability of climate over long periods of time.
My main concern with that position is that it is whistling in the dark.
That’s just about what I was thinking. Anything that pointed out that the “all other things being equal” clause doesn’t describe reality would be sufficient.
That’s what I meant with argument about climate models, different models suggest different mixes of positive and negative feedback.
Actually I’d be much more worried about CO2 emissions if I was convinced there was a strong dampening effect of unknown origin. That suggests the system might potentially be stressed to the breaking point, and afterwards a runaway process might result in vesusification. Even a very small risk of that would dominate all other climate related risks.
It’s possible that CO2 might not have any such effect on aggregate in a complicated system, but that would be quite remarkable
Not particularly remarkable. Homeostatic systems are the norm in the world, not the exception; and there are plenty of negative feedback mechanisms for CO2, starting from the most trivial one of more CO2 → more photosynthesis → (hopefully) more biomass not biodegraded back into carbon circulation.
I think it’s widely accepted such mechanism will bring CO2 levels back to their original equilibrium once anthropogenic emissions end, unfortunately over thousands of years. But—similar mechanisms for methane and CFCs are far faster and we might be already past peak atmospheric methane/CFC.
more CO2 → more photosynthesis → (hopefully) more biomass not biodegraded back into carbon circulation.
The upper bound for photosynthesis is constrained by plant populations and the area they cover, not atmospheric CO2 -- adding more CO2 to the air doesn’t necessarily increase photosynthetic activity. Human metabolism doesn’t increase in step with the number of calories you consume; there’s a limit to the base rate at which those biological processes can operate, independent of how much of their base inputs are lying around. Biology is more complicated than that.
RuBisCO activity is usually the limiting step in photosynthesis, and it depends on CO2 concentrations (or CO2 to O2 ratios). Adding more CO2 to the air will increase photosynthetic activity, there’s no doubt about it.
RuBisCO is the rate-limiting factor for plants, yes. But there’s more CO2 in the air naturally than they can adjust upward to compensate for, even before we factor in human-generated sources. The RuBisCO reaction is not maximally-efficient, which is why attempts to increase the rate of enzymatic activity are at the forefront of genetic engineering research into carbon sequestration. Additionally, the two relevant parameters (carbon dioxide fixing and oxygen incorporation) may already have struck a maximally-efficient tradeoff balance in many species of plants; self-modifying to favor increased CO2 fixation is not a trivial step; the gains here can be translated to losses over there, elsewhere in the biosystem. The organism is not its parts.
Anyway, if tomorrow we come up with plants that have a higher efficiency rate of carbon dioxide fixing, and they start pulling more CO2 from the air per unit time, that won’t fundamentally change that the population of plants and the room for them to grow is the determining factor in how much photosynthesis gets conducted—the RuBisCO reaction occurs in plants and protists such as algae when we’re talking about the macroscale, and basically nothing else.
Posit an artificial photosynthetic cell that can pack greater efficiency than the best of plants into the same surface area, and things are different. But we don’t have any such thing as yet.
Some skeptics do actually dispute the absorption effect of CO2.
That is, they claim that the spectrum of CO2 has been faked? Or deny that there is such a thing as a spectrum?
The proposed mechanism by which CO2 does not cause overall warming is a negative feedback loop.
I was aware of feedback loop proposals, but they seem to amount to arguing for a weaker AGW effect rather than none. I tend to mentally file them under squabbling about the exact models rather than AGW denial.
Are there any such proposed loops that would result in zero or effectively zero warming? ITSM that all feedback loops that involve actual warming as a step would not qualify because to result in effectively zero warming the effect would have to be strong enough to drown out temperature changes from all other causes unless overwhelmingly strong.
The leading skeptics (e.g. Roy Spencer) claim that negative feedback loops (due to clouds that reflect heat back into space) will reduce the warming effect of CO2 to be within the fluctuations Earth naturally experiences. So it’s a serious denial, rather than a minor squabble. And the views of the opposing experts (also in the link I sent) strongly indicate Spencer and his colleagues are mistaken (one such reason is that without a positive feedback, it’s very hard to explain the rapid shift in temperatures we know occurred between glacials and interglacials).
The skeptics who deny CO2 actually has an effect at all are fringe. The link I sent has the most qualified expert I could find (Gerhard Gerlich) who holds that view. Given that even the NIPCC (Non-Governmental International Panel on Climate Change) hasn’t subscribed to this position, I disregard its importance.
The leading skeptics (e.g. Roy Spencer) claim that negative feedback loops (due to clouds that reflect heat > back into space) will reduce the warming effect of CO2 to be within the fluctuations Earth naturally
experiences.
I don’t know as I’d find that comforting, considering that the Cretaceous climate was within fluctuations the Earth naturally experiences, and transitioning to that in such a short time would still be a pretty darn significant systemic shock to economy and ecology alike...
EDIT: To be clear, I’m not saying we’re headed for a new Cretaceous, just that “fluctuations the Earth naturally experiences” could still allow for some pretty steep gradients between the last century and any plausible, randomly-selected point within the known range.
There seems to be plenty of motivated arguing on both sides. But even though climate science is complicated the basic mechanism for CO2 raising temperatures is really simple and well supported by basic science. No one is disputing CO2′s absorption spectrum (that I know of). It’s possible that CO2 might not have any such effect on aggregate in a complicated system, but that would be quite remarkable and I don’t think any mechanism has been proposed (other than that global warming is miraculously balancing out a coming ice age).
My litmus test for whether someone even has the basic knowledge that might entitle them to the opinion that anthropogenic climate change isn’t happening is: “All other things being equal, does adding CO2 to the atmosphere make the world warmer?”
The answer is of course “yes.” Now, if a climate change non-skeptic answers “yes” the follow up question to see if they are entitled to their opinion that anthropogenic climate change is happening: “How could a climate change skeptic answer ‘yes’ to that question?” The correct answer to that is left as an exercise for the reader.
For example like this:
Yes, but the behavior of one component of the system doesn’t necessarily determine the behavior of the system as a whole. It’s the responsibility of those who propose an anthropogenic climate change to prove that it’s happening, not the other way round.
Most of the actual scientific debate seems to be centered around the reliability of the temperature record (and of different proxies) and of climate models (I consider it very likely that the skeptics are right on many of these issues), not around the question whether an anthropogenic climate change of some level is happening at all. At least I’m not aware of any climate scientist making the argument that no anthropogenic warming effect could possibly exist due to X (where X is some [proposed] physical reality, not something of the sort “that would be human hubris”).
Richard Lindzen is a nut, but he’s also an MIT professor of meteorology who has made arguments from physical reality (mostly) that AGW isn’t real.
The closest thing I could find on that page and the the most promising looking links was the water vapor argument (which is more of an argument that AGW should be smaller than expected rather than non-existent) and he apparently doesn’t subscribe to that anymore. Other than that he seems content to cast doubts and make accusations against the other side. If he has a new X, is there any good summary anywhere?
Just out of interest, what would have been the correct answer to the test (rot13 if you don’t want to spoil it)?
The position of “sane” climate skeptics appears to be that rising CO2 levels’ effects on temperature will be dampened by other regulatory causal effects; the evidence for the existence of such regulatory feedback is the overall stability of climate over long periods of time.
My main concern with that position is that it is whistling in the dark.
That’s just about what I was thinking. Anything that pointed out that the “all other things being equal” clause doesn’t describe reality would be sufficient.
That’s what I meant with argument about climate models, different models suggest different mixes of positive and negative feedback.
Actually I’d be much more worried about CO2 emissions if I was convinced there was a strong dampening effect of unknown origin. That suggests the system might potentially be stressed to the breaking point, and afterwards a runaway process might result in vesusification. Even a very small risk of that would dominate all other climate related risks.
Not particularly remarkable. Homeostatic systems are the norm in the world, not the exception; and there are plenty of negative feedback mechanisms for CO2, starting from the most trivial one of more CO2 → more photosynthesis → (hopefully) more biomass not biodegraded back into carbon circulation.
I think it’s widely accepted such mechanism will bring CO2 levels back to their original equilibrium once anthropogenic emissions end, unfortunately over thousands of years. But—similar mechanisms for methane and CFCs are far faster and we might be already past peak atmospheric methane/CFC.
The upper bound for photosynthesis is constrained by plant populations and the area they cover, not atmospheric CO2 -- adding more CO2 to the air doesn’t necessarily increase photosynthetic activity. Human metabolism doesn’t increase in step with the number of calories you consume; there’s a limit to the base rate at which those biological processes can operate, independent of how much of their base inputs are lying around. Biology is more complicated than that.
RuBisCO activity is usually the limiting step in photosynthesis, and it depends on CO2 concentrations (or CO2 to O2 ratios). Adding more CO2 to the air will increase photosynthetic activity, there’s no doubt about it.
RuBisCO is the rate-limiting factor for plants, yes. But there’s more CO2 in the air naturally than they can adjust upward to compensate for, even before we factor in human-generated sources. The RuBisCO reaction is not maximally-efficient, which is why attempts to increase the rate of enzymatic activity are at the forefront of genetic engineering research into carbon sequestration. Additionally, the two relevant parameters (carbon dioxide fixing and oxygen incorporation) may already have struck a maximally-efficient tradeoff balance in many species of plants; self-modifying to favor increased CO2 fixation is not a trivial step; the gains here can be translated to losses over there, elsewhere in the biosystem. The organism is not its parts.
Anyway, if tomorrow we come up with plants that have a higher efficiency rate of carbon dioxide fixing, and they start pulling more CO2 from the air per unit time, that won’t fundamentally change that the population of plants and the room for them to grow is the determining factor in how much photosynthesis gets conducted—the RuBisCO reaction occurs in plants and protists such as algae when we’re talking about the macroscale, and basically nothing else.
Posit an artificial photosynthetic cell that can pack greater efficiency than the best of plants into the same surface area, and things are different. But we don’t have any such thing as yet.
It’s a good habit to avoid the Appeal To Ignorance of an opposing view.
Some skeptics do actually dispute the absorption effect of CO2.
The proposed mechanism by which CO2 does not cause overall warming is a negative feedback loop.
I actually agree with your conclusion, but here’s the evidence you need to back up the specific cases you brought up:
Does atmospheric CO2 cause significant global warming?
Do negative feedback loops mostly cushion the effect of atmospheric CO2 increases?
That is, they claim that the spectrum of CO2 has been faked? Or deny that there is such a thing as a spectrum?
I was aware of feedback loop proposals, but they seem to amount to arguing for a weaker AGW effect rather than none. I tend to mentally file them under squabbling about the exact models rather than AGW denial. Are there any such proposed loops that would result in zero or effectively zero warming? ITSM that all feedback loops that involve actual warming as a step would not qualify because to result in effectively zero warming the effect would have to be strong enough to drown out temperature changes from all other causes unless overwhelmingly strong.
The leading skeptics (e.g. Roy Spencer) claim that negative feedback loops (due to clouds that reflect heat back into space) will reduce the warming effect of CO2 to be within the fluctuations Earth naturally experiences. So it’s a serious denial, rather than a minor squabble. And the views of the opposing experts (also in the link I sent) strongly indicate Spencer and his colleagues are mistaken (one such reason is that without a positive feedback, it’s very hard to explain the rapid shift in temperatures we know occurred between glacials and interglacials).
The skeptics who deny CO2 actually has an effect at all are fringe. The link I sent has the most qualified expert I could find (Gerhard Gerlich) who holds that view. Given that even the NIPCC (Non-Governmental International Panel on Climate Change) hasn’t subscribed to this position, I disregard its importance.
The arguments and experts are all summarized here (it’s a wiki, so you can add to it yourself if you find something new):
http://www.takeonit.com/question/5.aspx
I don’t know as I’d find that comforting, considering that the Cretaceous climate was within fluctuations the Earth naturally experiences, and transitioning to that in such a short time would still be a pretty darn significant systemic shock to economy and ecology alike...
EDIT: To be clear, I’m not saying we’re headed for a new Cretaceous, just that “fluctuations the Earth naturally experiences” could still allow for some pretty steep gradients between the last century and any plausible, randomly-selected point within the known range.