I got in on the tail end of the discussion of Scott Sumner’s post in which he discusses global warming. I posted a comment but it was probably too late for most people to notice.
I think the issue is more complicated than Scott seems to suggest.
Scott writes:
Theory suggests that higher levels of CO2 should raise global temperatures due to the “greenhouse effect”.
True.
But what that doesn’t tell us is how strong the effect is. I’m not disagreeing with Scott. I’m simply saying that the effect could be strong or could be weak. If a substantial increase in CO2 led to 0.1 degree C increase in temperature, we would have little to worry about. We can’t simply look at the fact that CO2 increased and then the temperature increased and attribute the whole increase in temperature to the increase in CO2.
Take an example from the world of economics, which, of course, Scott and I are more familiar with. We posit that a substantial increase in the minimum wage will cause a substantial reduction in the number of jobs of low-skilled workers. That’s simply good economic theory. So we look at the data and see that, sure enough, a few dollar an hour increase in the minimum wage is accompanied by a substantial reduction in the number of jobs of low-skilled workers.
But that doesn’t tell us how much of the reduction in jobs is due to the increase in the minimum wage.
Similarly, it’s bad methodology to key in on one variable, CO2 concentration, and not look at other factors that could cause global warming.
READER COMMENTS
Jon Leonard
Jun 3 2024 at 10:14am
The heat-trapping effects of CO2 are from a physics perspective pretty straightforward: CO2 absorbs well in the infrared range, and when it re-emits it does so in a random direction; more CO2 makes it slower for heat energy to get all the way through the atmosphere, and the effect goes more or less as the log of the concentration. The tricky part is figuring out how the other parts of the ecosystem interact with this; the standard models assume that other somewhat underspecified mechanisms quadruple this effect. Politics then complicates careful study of this, and also discussions of to what extent, and how, this should be addressed.
David Henderson
Jun 3 2024 at 10:30am
Right, and although I’m not as up on the literature as I was a few years ago, I do recall that clouds matter a lot and that no one has successfully modeled clouds. “I really don’t know clouds at all.”
Roger McKinney
Jun 3 2024 at 10:57am
I’ve seen analysis of the data that shows CO2 lagging behind warming, suggesting it is an effect not a cause.
Also, the global warming models have a margin of error of 25 degrees because they can’t incorporate cloud effects. Cloud effects have been modeling Achilles heal for 40 years.
Andrew_FL
Jun 3 2024 at 11:46am
The effect you are talking about is on a time scale of thousands of years, not decades.
JoeF
Jun 4 2024 at 8:15am
Not true, see this analysis (which has not been refuted AFAIK) for 1958-2022:
https://www.mdpi.com/2413-4155/5/3/35
Andrew_FL
Jun 4 2024 at 10:17am
It’s easy to refute. The amount of CO2 from fossil fuel burning and land use since the industrial revolution began is roughly double the increase measured since then. This requires that Nature, on average, is a net CO2 sink, not source, over this period. The observed effect of temperature at Mauna Loa can be easily explained as modulation of the seasonal rate of natural absorption by the tropical oceans by temperature variations mostly associated with the ENSO phenomenon. If small temperature variations could cause CO2 to increase so much (and at what temperature, exactly, would it cause them to decrease in this model, pray tell? There has to be an equilibrium point or else CO2 levels would simple increase forever even if temperature remained static.) this would a source of wild instability inconsistent with the history of life on Earth.
JoeF
Jun 4 2024 at 3:07pm
You may be right. His data and methods are right there in the paper for you to refute and he has won the highest awards in international hydrology (2009,2014), so it would be quite the achievement.
steve
Jun 3 2024 at 3:04pm
Actually, there has been a lot of research on the effects of clouds. There was an assumption on the part of people 15-20 years ago that clouds reduced warming but that was made without any evidence. Since then there has been a lot of information accumulated and it’s clear that not all clouds act the same. Warm clouds probably add to warming effects and cold clouds reduce warming. Lower clouds may reflect sun but the high wispy clouds may have an insulating effect. Adding it all up the 6th IPCC statement thought clouds may have a small additive effect on warming but noted we need more research.
Steve
TMC
Jun 5 2024 at 7:02pm
Steve, your statement seems to support David’s “no one has successfully modeled clouds”.
Roger McKinney
Jun 5 2024 at 10:02pm
Yes, research, but cloud effects are still too complex to include in their models.
Variant
Jun 3 2024 at 2:33pm
This is a really good presentation from a few years back by Warren Meyer that touches on the theoretical feedback effect of CO2.
In short, CO2 is certainly a greenhouse gas, but the supposed multiplicative effect from its addition to the atmosphere has not correlated with the predicted temperature increase, and generally fails to consider alternate drivers like solar cycles.
Kevin Dick
Jun 3 2024 at 2:41pm
I thought about making a similar comment on Scott’s post, but let it pass.
The somewhat ironic thing is that his general point argues _against_ doing anything about global warming. I take that general point to be, “Start by assuming the basic textbook answer is correct.”
The basic textbook answer on CO2, IIRC, is that a doubling of CO2 from 280 t0 560ppm would result in a 1.2 deg C increase. This is the radiation calculation with no “feedbacks”. We should reach this concentration by about 2100.
As far as I can tell, nobody thinks a 1.2 deg C rise by 2100 is much to be concerned about. All the motivations for taking drastic actions are for complex atmospheric models that predict several times more warming and have analogous issues to complex macroecronomics models.
David Henderson
Jun 3 2024 at 4:47pm
Interesting. Thanks, Kevin.
Richard W Fulmer
Jun 3 2024 at 5:42pm
The problem with doing “something” about global warming is that a lot of the “somethings” mandated by governments around the world have made the problem worse: corn-based ethanol in the United States, biomass power plants in the UK, and retiring nuclear power plants in Germany.
When they fail, government-mandated programs have four main drawbacks: (1) they fail on a very large scale, (2) they fail expensively, (3) they’re politically hard to end because the people who benefit from them lobby to keep them in place, and (4) their failure angers voters, making them unlikely to support future “somethings.”
Mactoul
Jun 3 2024 at 10:41pm
Slight warming due to CO2 is amplified by increase in water vapor in the slightly warmer atmosphere.
Thus the 1.2 C textbook answer has to be revised. The ECS is typically provided as 1.5-3 C
Kevin Dick
Jun 4 2024 at 1:51am
Actually, if you look at the central estimate of the entire literature on EXS, you get 1.6 deg C
To Scott’s point
https://grokinfullness.blogspot.com/2017/04/publication-bias-in-climate-science.html?m=1
Harry Kloppert
Jun 3 2024 at 4:58pm
I read that doubling the density of CO2 results in 0.6 to 1.2 deg C dependent on the expert . Prof. William Happer calculates that it will be 0.7 deg C. The IPCC adds a positive feed-back-loop to the formular: More heat will add more moisture from the oceans to the air. And H2O ist another strong greehouse gas… I don’t agree: If this feeback loop does exist, we should be able to measure it. The encrease in water vapor in the air should follow the same curve as the CO2 encrease! I haven’t seen that curve yet.
Thomas L Hutcheson
Jun 3 2024 at 6:03pm
But large climate models DO attempt to include everything; indeed, that is the only way to calculate the NPV of different possible policies to optimize CO2 concentration in the atmosphere.
Mactoul
Jun 3 2024 at 10:07pm
The parameter equilibrium climate sensitivity ECS quantifies the warming expected per doubling of CO2 concentration.
ECS is typically given as 1.5-4.5 C and the range hasn’t narrowed down in 30 years of research.
So practical consequences of CO2 increase depend on quantitative warming expected and the climate science hasn’t helped yet in getting a clear answer.
Andrew_FL
Jun 4 2024 at 10:19am
Thirty years? Try forty five. That range is right out of the Charney Report from 1979.
Jim Glass
Jun 4 2024 at 12:40am
The opportunity to hold warming to 1.2 degrees C has fallen way, way back in the rear view mirror. Projections from models today center around an increase of 2.7 – 3 degrees C.
Sabine Hossenfelder surveys the projections and the various plans to contain warming (that mostly aren’t being acted upon).
Roger
Jun 4 2024 at 12:21pm
It is rarely pointed out that the so-called greenhouse effect is essential to life on earth. The atmosphere is a relatively poor absorber of solar energy. What the atmosphere does better is absorb energy captured by the surface and reemitted at a different spectrum. CO2 is not the only gas in the atmosphere playing a role in this process and is not even the most important. Water vapor has a powerful effect, but it seems too difficult to include it in models.
There is at least one atmosphere scientist out there that claims that CO2 concentrations are near the point where they cannot capture any more energy. The amount of energy falling in the right part of the spectrum is approaching complete capture.
The science is quite complicated and many parts are not that well understood.
BS
Jun 4 2024 at 12:30pm
If the computational models for predicting temperature change decades from now are as good as the computational models for predicting economic conditions six months from now, I wish everyone luck.
Mike Burnson
Jun 5 2024 at 4:34pm
Far, far more is left out of so-called greenhouse gas commentary than is included, to the severe detriment of honest debate and discussion. None of the previous posts addresses any of these, most likely because the AGW fraud machine has blocked publicizing them. Google and other searches bury these details.
The first indisputable fact is how trivial the human contribution to atmospheric gases. We are merely 1/3 of 1% of total emissions, including the massive increases by China and India this century. Water vapor is almost 95% of the GHE, and we have zero impact on that: the Earth’s surface is 75% water. Carbon dioxide is less than 5%, and all other gases are less than 1%. Human activity is perhaps 6% of total CO2, natural CO2 the other 94% or so. That’s 1/3 of 1% due to humans.
No, human activity is NOT causing and global warming.
Mike Burnson
Jun 5 2024 at 4:44pm
Now, let’s take that a step further: the effect of increasing CO2 is NOT linear. It is a curve quite similar to the natural logarithm. At just 85 ppm, 90% of the absorbance capacity of CO2 has already been saturated. By 300 ppm, CO2’s absorbance is 99%, essentially opaque. Above 300, any additional effect from CO2 is all but impossible to measure. As pointed out previously, CO2 is a LAGGING indicator, caused by rising temperatures, not causing them.
The Earth has been warming for three centuries already, since the end of the Little Ice Age. The Earth was much warmer during the Medieval Warming Period (and Roman WP, too), to the extent that Vikings had self-sustaining colonies on Greenland where they cannot exist today; and they cultivated grape vines in what is now Nova Scotia (there is some debate on this point).
Mike Burnson
Jun 5 2024 at 5:06pm
The extent of fraud and pseudoscience in global warming “research” is unparalleled in science history. From the start, we now have forty years’ worth of predictions – and not a single one has actually come to pass. There was the total fraud of the hockey stick graph; it gained attention for the singular reason that it falsely “eliminated” both the Little Ice Age and the Medieval Warming Period. The narrative about AGW has changed constantly, from upper atmospheric warming to surface to infrared emissions from the surface. Denials of the urban heat island effect went on for years: they distorted historical readings in a manner convenient to the fraud. Ocean acidification was absolutely false from its inception: global waters retain LESS CO2 as they warmed since the LIA ended. The warming hiatus yielded more than 60 “studies” explaining it; falsified garbage from NOAA magically claimed there was none! So why the 60+ “studies”? Claims about increased forest fires, increasing tornadoes, etc, have all been disproven, yet these falsehoods persist.
Honest discussion has been blocked because the fraud machine gets $100 billion every years from governments globally.
John
Jun 5 2024 at 7:08pm
One thing I don’t understand is: what is the life or half-life of a doubling if CO2 in the atmosphere? I had assumed the answer was that atmospheric CO2 has a very long half-life (say thousands, 10s of thousands or hundreds of thousands of years because where could the stuff posdibly go?) However, I recently had a discussion with a knowledgable climate scientist who said it was only a couple of hundred years. I was very surprised to hear him say this, and a bit confused as to why he seemed uninterested in why this matters.
To me, the answer has a huge bearing on the cost/risk issue. A very long half-life would imply global warming effects are almost permanent, and thus would worsen over time because of the compounding effect, even if we were to moderately reduce future emissions. This could lead to catastrophic consequences, especially if actual effects turn out worse than the models predict. One the other hand, a half-life of a couple of hundred years would make a “catastrophic” case much less likely, and also bode much better for less severe scenarios, as our ability to reduce CO2 emissions will likely improve over the next 50 to 100 years, even in the absense of govt mandates. Bottom line, similar to the effects of compound interest versus no compounding, the difference is huge over hundreds of years.
Any reader input on CO2 half-life question would be much appreciated. Also, if the half-life really is in the range of hundreds of years, where does all the CO2 go? In the ocean, oceanic algae or something?
Jonathan Seder
Jun 5 2024 at 11:54pm
Since 2006, Andrew Watts has been hosting a debate on climate research at wattsupwiththat.com, generally favoring the view that there is no “crisis.” His “Failed Prediction Timeline” is very interesting.
A summary page on Climate Sensitivity – with “pro” and “con” arguments – is here: https://wattsupwiththat.com/climate-sensitivity/
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