Discussion > A temperature timeline for the last 22,000 years
EM. Go for it. You set them up, I'll knock em down if they include any CO2 nonsense. There are probably dozens of thermostats, some of the more important ones being caused by life itself. I think you are fully aware of many of them.
I note that you didn't explain one of my major problems with the AGW hypothesis - namely that with increasing CO2 in the atmosphere causing an ever decreasing effect on temperatures, and feedbacks reacting to temperature and not to CO2, how can increasing CO2 produce increasing feedbacks? Claims of accelerating changes would require increasing effects from feedbacks.
ACK
It has always amazed me that plants did not become extinct having used up all but a minute trace of CO2 in the atmosphere.
golf charlie
ACK
I am not sure that you can claim that CO2 has no effect on climate, while simultaneously saying that the warming varies logarithmically with CO2 concentration. One or the other, my friend! ;-)
Let's look at the logarithmic effect.
Increase the CO2 concentration from the previous industrial 280ppm to the present 405ppm, an increase of 125ppm.
Using Martin A's favourite equation the eventual warming would be 5.35ln(405/280)3/3.7 = 1.6C
Add another 125ppm and we get a further increase of 5.35ln(530/405)3/3.7 = 1.17C
At current rates that will occur around 2040.
Each extra increment of CO2 does indeed cause less warming than the previous increment. Unfortunately the difference between the log increase and the linear increase is too small to be significant in the real world. An increase of 2.77C instead of 3.2 C in 2040 is not going to solve the problem.
Entropic man
At current rates that will occur around 2040.
Sep 21, 2016 at 6:53 PM | Entropic man
What current rates? Based on the last 20 years when Global Warming failed to occur in accordance with your equations?
golf charlie
EM, sorry forgot to add...
15+ years ago, I would have accepted your statement, and other predictions made by climate science. Now you and others deny that Climate Science ever made any predictions as the score is 0/10.
Why are you so confident to continue to "project" future temperatures, when based on past performance by others, there is a fundamental flaw somewhere in your equations, and the equations used by 97% of Climate Scientists?
golf charlie
Wow, Entropic man (or may I call you Ent? Somehow, it seems apt), you really are fixated on CO2, aren’t you? Face it, it is just a minor gas in our atmosphere, and, whatever its source, human or otherwise, it is not going to drive us to doom and destruction.
All explanations of “young suns” and “larger thermostat problems” and your timescales of hundreds of millions of years are just guesswork based on what little we do know; all the evidence to date (real evidence, not that which has been cooked up by people with a different agenda from science) is that CO2 concentrations are driven by temperatures, though many accept that there will be many other factors involved, not all of which have been identified, yet – and may never be, with science being blinded by unquestionable consensus.
IF you could gather data for the past few thousand years, let alone the past few hundred million years, to the level of detail that we have manage to collate over the past couple of centuries decades, then perhaps – just perhaps – we might be able to formulate some hypotheses that are closer to reality than we can at present. However, as we cannot do that, we just have to make wild guesses and assumptions – and we also have to accept that most of these will eventually prove to be wrong. In short: the answer to your “big question” is: “Whatever… it happened, is happening, and will continue to happen. There is nothing you can do to affect it, so live with it.”
The reason why your friend, ACK, can give you such a dichotomous statement is that the salient properties of CO2 can be shown in the lab, however, we have no knowledge of how effective this is in the entire atmosphere, though the indications, to date, are… not much; observations show that CO2 concentrations tend to be led by temperatures, NOT the other way round.
The real big question is: “Will science ever recover from its obsession with delivering answers that politicians want, rather than the truth?”
Anyhoo… getting back to XKCD, do this and this remind you of anyone?
Radical Rodent
EM. Don't know where you get your figures from. IPCC (and sceptics) agree that the warming due to a doubling of CO2 will be c. 1oF, but this is a theoretical calculation substantiated by experiment in laboratory conditions. It is also generally agreed (except by sceptics) that the temperature rise since the advent of the industrial age has been only c. 1oC. That increase must include any positive feedbacks and any changes caused by non human-induced changes or by humans changing the Earth's surface.
So I repeat my question, how can an ever decreasing change in temperature caused by CO2, cause every increasing feedbacks?
Note I have never denied that CO2 is a greenhouse gas. I do question whether it has any meaningful effect once its atmospheric concentration exceeds c. 300ppm.
ACK
Sep 21, 2016 at 5:59 PM | golf charlie
Doesn't the really noticeable decline in atmospheric CO2 coincide quite well with the evolution of trees? I agree basically plants are killing us all by using up CO2 at an alarming rate, aided and abetted by shelled sea life. All that "carbon" which was once available has been used up by nature's carbon capture and storage. Yet no-one seems concerned.
SandyS
Golf Charlie, Radical rodent
What current rates? Based on the last 20 years when Global Warming failed to occur in accordance with your equations?
This is GISTEMP from 1970. I've added the linear trend and the "no warming since 1998" linear trend. Both show an ongoing increase of 0.17C/decade. The latest post El Nino figures sit squarely on the long term trend.
Note that 0.17C/decade will add 0.68C by 2040. This would bring the anomaly temperature to 1.48 and the warming since 1880 to 1.68. This is close to my calculated prediction of 1.68.
Could you please explain how this data demonstrates that "Global warming has failed to occur."
ACK
The IPCC estimate that the direct effect of increasing atmospheric CO2 is about 1C/doubling. When you add in the mid-range climate sensitivity of 3, you get the 3C/doubling observed in the real world.
If you gave forgotten the formula I used, C/Co is the change in CO2. 3 is the climate sensitivity and 1/3.7 is the conversion from watts to degrees centigrade.
I'm quite happy to accept that the increase in temperature with CO2 is less than linear.Note that nowhere in the paleo data do we see global temperatures above 25C, 10C above the preaent and around 1000ppm. Even under Venus conditions (95%CO2 at 90 Bar) the temperature is only 120K above Earth.
Unfortunately we are presently around 400ppm and the curve is steeper.
I do question whether it has any meaningful effect once its atmospheric concentration exceeds c. 300ppm.
May I ask how you reach this conclusion? Is it an opinion or do you have a scientific basis? If so, I would be interested to see the formula you used and sample calculations. Perhaps 280ppm to 400pp and 280ppm to 530ppm as I did. Also the 200ppm to 280ppm which accompanied the transition to the Holocene.
Speaking of the Holocene, from my viewpoint the 80ppm increase in CO2 turned a 1C Milankovich warming into a 5C temperature rise. That suggests a climate sensitivity closer to 5 than 3. Once again, a decrease in sensitivity with increasing CO2 is possible, but unlikely to make much difference in the 400-600ppm range we are dealing with.
Entropic man
EM, modelled climate data is just that.
Back on the real Planet Earth, nothing is happening as modelled, so why should anyone care?
golf charlie
ACK
If the physicists are correct, the global temperature difference between 0 CO2 and 280ppm CO2 is 33C. You suggest that the graph then flattens abruptly at 300pp.
If the first 300ppm produces a 33C change and anything over 300ppm produces no change at all, his inflection makes the accepted logarithmic curve look minor.
I would really like to know the physics behind your belief.
Entropic man
Golf Charlie
Nothing modelled. GISTEMP is observed data.
The question remains. Stop dodging.
Entropic man
EM. This grows tiresome. You have had this debate many times before with those more adept at addressing your overly simplistic treatment. What you can measure in the laboratory or calculate using crude equations bears little resemblance to the enormously complex reality that is Earth's climate. You are like someone trying to use a formula to calculate how heat accumulates in a saucepan of water on a hob. Unfortunately you have concentrated on calculating heat accumulation and don't recognize or fully appreciate how heat is being lost from the pan. There are an extraordinarily large number of negative feedbacks in the climate system that you ignore with your simplistic formulae. The geological record is one of stability suggesting the dominance of negative feedbacks.
ACK
ACK
Yes, it is getting tiresome.
You have an opinion about the behaviour of climate which lacks any formal structure, evidence or basis in physics.
I have tried repeatedly to pull you beyond the old straw man of incomprehensible complexity into some proper scientific thinking, but you hang onto your unscientific beliefs with a desperate grip.
By the way, I looked up your gas cloud hypothesis for snowball Earths. Apart from one speculative paper I found no supporting evidence.
Entropic man
ACK
You didn't answer my question., just wished it a supposed profusion of feedbacks.
Why do you expect the first 300ppm of C02 to produce 33Cwarming and then nothing at higher concentrations?
What change in the properties of CO2 kicks in abruptly 300ppm.. How did you deduce, measure or calculate this abrupt change?
Entropic man
EM. If you are going to question me on what I have written make sure you understand every part of what I have written:
"I do question whether it has any meaningful effect once its atmospheric concentration exceeds c. 300ppm" is not the same as having no effect.
You cannot prove that the temperature change produced by a 300 ppm change in CO2 is 33oC, so your question is meaningless.
And you studiously ignore the effects of negative feedbacks on every simplistic calculation you try to foster on me.
ACK
EM. Re Snowball Earth hypothesis, try Sherlock Holmes reasoning.
ACK
EM, GISTEMP is adjusted/homogenised data.
Just because you bought a dead horse that is going nowhere,, stop trying to flog it on.
golf charlie
ACK
What negative feedbacks do you have in mind? Don't forget the evidence.
Are you sure you were a scientist? Scientists don't deal in proof.
I checked your gas cloud hypothesis. No evidence.
Entropic man
EM. What evidence do you suggest might be found? The fact that no evidence exists (has it even been looked for?) is not any reason to dismiss a hypothesis. BTW its not MY hypothsis.
ACK
Ent, are you sure you have taken into account all possible variables that could be taken into account in your precious formulae? If so, could you list them for us? If not, why not?
Radical Rodent
ACK
As I said, go to Venus and you find the CO2 greenhouse effect working at 95℅CO2 and 90 Bar. That is rather more than 300ppm at 1 bar.
Pretend you are giving a seminar Clearly describe your view of the greenhouse effect, with supporting evidence. You have been rather vague so far.
Entropic man
EM. I have resolved that when matters become personalized, I will stop communicating or debating. So try your techniques on others.
ACK
Ent, if you do go to Venus, you will find that, at altitudes where the atmospheric pressure is the same as that at the Earth’s surface, the temperature is exactly what the Earth’s surface temperature would be, were Earth the same distance from the Sun as Venus is. Given that the CO2 concentration on Venus is around 97% – i.e. a little over 11 doublings of Earth’s CO2 concentration – one would have thought that, for those theories / hypotheses that you hold so dear, the temperatures should be at least 11°C warmer. But, hey, what does reality have to do with your theories? There is very strong evidence to suggest that the temperature of a planet’s surface has more to do with its surface pressure, as well as its distance from the principal energy source in the system, than effects that any part of its atmosphere may have.
Perhaps you should start reading more about Svensmark’s theories, rather than be obsessive about the only component of the atmosphere that it has been deemed humans might be able to have some noticeable effect upon.
Radical Rodent
ACK
This is still not what I'm looking for. I'm interested in timescales of hundreds of millions of years, not a couple of million. Nor am I interested in assigning a separate explaination for every event.
There has been life on Earth since the first stromatolite 3.8 billion years ago and something has kept the plant liveable throughout.
What I am looking for is the underlying mechanism, if any.