A new paper published in Ecological Modelling finds climate sensitivity to doubled CO2 concentrations is significantly lower than estimates from the IPCC and climate models which “utilize uncertain historical data and make various assumptions about forcings.” The author instead uses a ‘minimal model’ with the fewest possible assumptions and least data uncertainty to derive a transient climate sensitivity of only 1.093C:
“A minimal model was used that has the fewest possible assumptions and the least data uncertainty. Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal. This estimated rate of warming was related to the fraction of a log CO2 doubling from 1959 to 2013 to give an estimated transient sensitivity of 1.093 °C (0.96–1.23 °C 95% confidence limits) and equilibrium climate sensitivity of 1.99 °C (1.75–2.23 °C). It is argued that higher estimates derived from climate models are incorrect because they disagree with empirical estimates.”
Otto et al find equilibrium climate sensitivity [over the next several centuries] is only ~1.3 times greater than transient climate sensitivity, thus the estimate of 1.093C transient sensitivity could be associated with as little as 1.4C equilibrium sensitivity, less than half of the implied IPCC central estimate in AR5 of ~3.3C.
Moreover, this paper does not assume any solar forcing or solar amplification mechanisms. The integral of solar activity plus ocean oscillations explain ~95% of global temperature change over the past 400 years. Including potential solar forcing into the ‘minimal model’ could substantially reduce estimated climate sensitivity to CO2 to a much greater extent.
- Empirical estimates of climate sensitivity are highly uncertain.
- Anthropogenic warming was estimated by signal decomposition.
- Warming and forcing were equated in the time domain to obtain sensitivity.
- Estimated sensitivity is 1.093 °C (transient) and 1.99 °C (equilibrium).
- Empirical study sensitivity estimates fall below those based on GCMs [Global Circulation Models].
Abstract
Climate sensitivity summarizes the net effect of a change in forcing on Earth’s surface temperature. Estimates based on energy balance calculations give generally lower values for sensitivity (< 2 °C per doubling of forcing) than those based on general circulation models, but utilize uncertain historical data and make various assumptions about forcings. A minimal model was used that has the fewest possible assumptions and the least data uncertainty. Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal. This estimated rate of warming was related to the fraction of a log CO2 doubling from 1959 to 2013 to give an estimated transient sensitivity of 1.093 °C (0.96–1.23 °C 95% confidence limits) and equilibrium climate sensitivity of 1.99 °C (1.75–2.23 °C). It is argued that higher estimates derived from climate models are incorrect because they disagree with empirical estimates.
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No surprise to most here, but would be if it shows up in next IPCC report.
The simple extrapolation in this paper tends to underestimate the TCR, as emissions of the past are supposed to have delayed effects.
So it’s only accurate to four significant digits.
When will they gat a better estimate we can trust ??
“””””…..1. What are the best methods to bound our ignorance about sensitivity
2. what do those methods show.
3. what additional observations do we need to constrain the problem further……”””””
#1 Why not measure it ??
#2 We don’t know its value.
#3 Need more observations of CS.
I emailed this paper to Anthony back in February when my list was updated but nothing was posted on it.
http://www.populartechnology.net/2009/10/peer-reviewed-papers-supporting.html#Sensitivity
Here is the email:
Sent By: populartechnology
On: Feb 02/15/14 11:34 PM
Subject: No one noticed the new Loehle (2014) low climate sensitivity paper on the list?
A minimal model for estimating climate sensitivity
(Ecological Modelling, Volume 276, pp. 80-84, March 2014)
– Craig Loehle
Abstract: Climate sensitivity summarizes the net effect of a change in forcing on Earth’s surface temperature. Estimates based on energy balance calculations give generally lower values for sensitivity (<2 °C per doubling of forcing) than those based on general circulation models, but utilize uncertain historical data and make various assumptions about forcings. A minimal model was used that has the fewest possible assumptions and the least data uncertainty. Using only the historical surface temperature record, the periodic temperature oscillations often associated with the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation were estimated and subtracted from the surface temperature data, leaving a linear warming trend identified as an anthropogenic signal. This estimated rate of warming was related to the fraction of a log CO 2 doubling from 1959 to 2013 to give an estimated transient sensitivity of 1.093 °C (0.96–1.23 °C 95% confidence limits) and equilibrium climate sensitivity of 1.99 °C (1.75–2.23 °C). It is argued that higher estimates derived from climate models are incorrect because they disagree with empirical estimates.
REPLY: My daily email traffic is often overwhelming, and if I have to spend more time on my actual business and life than WUWT that day, some things might not make it to publication, or get lost in the traffic. Don’t feel slighted/ignored because I can’t read, respond to, or act on every email – Anthony
Plotting the vast number of CSs to CO2 over time would be interesting and quite possibly amusing. A statistical analysis of the estimates coupled with some creativity could lead to endless fun.
Um, where, exactly, are those decadal cycles to be found? Not that your “A” isn’t a potent source of methane, a well-known GHG…;-)
Sigh. No, it’s
C. And proof that at least these climate researchers would lose points in my physics labs or any exams that required students to have a clue about significant figures in an answer.
But hey, at least they gave a — very likely completely unjustified — error estimate. Unjustified because in order for them to make an assessment of “95% confidence” they have to start by having a believable assumption for the distribution of error and the probability that the functional form that they are fitting is extrapolatable.
And that’s the rub, as Greg and I pointed out above. How can one assign “95% confidence” to any number extracted by assuming that reality is a sinusoid plus a linear trend, fitting that trend pre-1959 (only), then subtracting the extrapolated fit from the post-1959 data, fitting a linear trend to it, and assuming that this is the anthropogenic component of the post-1959 warming?
Try running the same trick backwards — to explain the proxy data prior to (say) 1850. Whooeee, doesn’t much work, does it, even over very short stretches into the past. Try running it back to (say) 1500 CE, and it becomes laugable. There is no physics-based explanation of the curve they are fitting, and if there were the physics would have to change radically and in unknown ways to work back to 1500, as then it would have to explain the Little Ice Age, and we can’t. Go back to 1000 CE and it is worse. Go back to 7,000 BCE (9,000 years ago) and their fit function is so far off from the linear trend alone that it predicts a profound ice age, not the Holocene Optimum 1-2 C warmer than today. So we know, beyond any doubt, that this model is utterly incorrect even a tiny distance outside of the fit interval. We know that our estimates of global average surface temperature are not precise to within 1 C anywhere. We pretend that the global average surface temperature anomaly is, when we know better, and ignore the fact that even if we know the “anomaly” relative to some baseline in the recent (35 year) past, our remote past anomaly knowledge is based on truly horrendous data extrapolations from increasingly imprecise and inconsistent data and therefore has enormous error bars, error bars so broad that they don’t really constrain any model very much, and error bars that are never drawn into any graph of the temperature anomaly lest the notion that we are certain of the warming be laughed out of the house.
So the improperly presented answer is has 95% confidence intervals based on Bayesian assumptions of the extrapolability of the model form fit and the assignability of the cause of the post-1959 surplus, assumptions that have a 2% probability (being generous) of being correct.
Right.
rgb
rgbatduke commented
rgb, I really like your comments, I bet your classes are a joy (even if I’d get demerits for too many significant figures)!
george e smith writes “#1 Why not measure it ??”
It is impractical to MEASURE climate sensitivity. It always was, and it will be into the indefinite future. That is why NO ONE, and I mean NO ONE has the slightest idea what its numeric value is.
Until it is recognized that I am writing the ONLY truth that matters on this issue, billions of dollars will go on being wasted trying to solve a problem that does not, and never did, exist,
Jim Cripwell commented
Well, I don’t know about that, but we do have to stop throwing the data we have that might lend insight in the trash. Every day, the Sun comes up, warms the ground, and then it sets, and the temp drops. Every day! Even better, Extratropic the ratio of day to night changes, every day. One could take and graph how temp evolve through the year, look to see if the slope is changing. Oh wait, I’ve already done this:
http://wattsupwiththat.files.wordpress.com/2013/05/clip_image028.jpg
It’s very small. If you base it on actual surface temp measurements, and don’t throw the good bits away.
Steven Mosher says:
July 23, 2014 at 9:43 am
“The science debate is…”
Thus the elders of the Church admonished Galileo: If you will just concentrate on the number and placement of the epicycles, you will be part of the “debate”.
You want to be part of the “debate”, doncha’? All the cool kids are doing it.
Let’s see what the AMO has to say about in a few weeks with another monthly number.
Mi Cro writes “Well, I don’t know about that”
OK. HOW do you MEASURE climate sensitivity? No fiddling. Give me the nitty gritty of HOW you measure climate sensitivity.
Jim Cripwell commented on
You have to measure the change in rate of cooling at night as the length of day changes, then compare that year over year as Co2 changes. But, you have to understand what other things can change this, it is changing ( http://wattsupwiththat.files.wordpress.com/2013/05/clip_image028_thumb.jpg?w=963&h=725 ), but getting past this is beyond my ability (at least at this time) and available time.
Jim Clarke said
with no requirement for regulation, than dis {sic} the paper as being ‘still wrong’.
Henry says
What do you want us to do? Deny our own results?
http://blogs.24.com/henryp/2013/02/21/henrys-pool-tables-on-global-warmingcooling/
There is no man made warming. None whatsoever. There simply is no room for it in my equation.
Live with it.
Steven Mosher & company including our host [most probably] all have an interest to keep “the debate” going, even if they know there is no AGW,
as if there were not hundreds of other interesting debates we could have, scientific or otherwise.
{they only have to change the rules}
The following charts are the historic CO2 sensitivity over the last 10,000 years, 200,000 years, 5 million years, 25 million years, 50 million years and 750 million years.
I’ve matched the timelines of the detailed global temperature estimates from dO18 isotopes with all the CO2 estimates which are available from reliable methods.
So, 2500 empirical datapoints pointing to +/- 40C CO2 sensitivity or randomness or something else is going on other than CO2.
http://s28.postimg.org/eucaualr1/CO2_sensitivity_last_10_Kys.png
http://s13.postimg.org/65wbml0p3/CO2_sensitivity_last_200_Kys.png
http://s10.postimg.org/4u651ipix/CO2_sensitivity_last_5_Mys.png
http://s23.postimg.org/3jnbzr9cb/CO2_sensitivity_last_25_Mys.png
http://s17.postimg.org/s2rwfp95r/CO2_sensitivity_last_50_Mys.png
http://s28.postimg.org/lovsbgt5p/CO2_sensitivity_last_750_Mys.png
“OK. HOW do you MEASURE climate sensitivity? No fiddling. Give me the nitty gritty of HOW you measure climate sensitivity.”
Simple.
Start with the definition
Climate sensitivity ( Not sensitivity due to doubling) is defined as
lambda = Change in Temperature/ Change in forcing
climate sensitivity to doubling c02 is RELATED to this but not the same thing,
lambda = delta Temp / delta Watts
It is easy to measure. You just measure delta T and you measure delta W.
Then it gets more complicated, because you realize that the value can change as a function of time. then there are uncertainties.
Take temperature. we can clearly measure it, but when we look at longer time scales and global extent our measurements become more uncertain. we call these estimates. they are derived
from measurements and are more uncertain. but its knowledge nonetheless
Take forcing. here too we can measure it ( like TSI), but over long periods of time what we end up with are estimates with wide error bounds. but its knowledge nonetheless
for example looking at the past 150 years we could say
that temperature change might be as high as 1C and as low at .5C
and we say that changing in forcing could be between 1 and 3 Watts
Those are just example numbers to give you the idea,
So the real science debate that people can join is this
1. What is the real temperature change?
2. what is the real change in forcing and how much of it is human caused.
If you want to join the debate, then that is where the action is.
That is why Parliment calls Nic Lewis to discuss sensitivity and why they dont call you.
he joined the debate. you debate the debate.
The first approach is winning. Joining the debate works.
debating the debate? doesnt work.
So while some skeptics join the debate and get published and influence the IPCC (nic lewis) other skeptics debate the debate, never make a contribution to science, and waste their time on blogs, pounding a tiny drum that nobody hears.
personally, I’ll spend my time being productive. That means answering the change in temperature question as best I can.
Mi Cro says:
July 23, 2014 at 10:23 am
If they used published temp series (which is what they look like), it’s still too high.
If you make the time series based on max temps (instead of average), there is no trend.
########################
If you want to join the debate. Publish your work .
posting on the internet doesnt count.
looking at your work.. I can say it not publishable. sorry.
Steven Mosher commented
No need to be sorry, I know it’s not. But I also know (well suspect) even if I put all of the bows and ribbons on it to get it published, a reviewer like you would reject it.
I also know that I lack abilities that would be required to get it to that point, as well as the free time to learn everything I need to know.
But, the data is good, and it is telling. And what BEST does is “wrong”, but so is what the rest of you are doing, so don’t feel bad.
Also I asked you the other day about the difference between publishing in a blog that is viewed and debated by very large numbers (and available to any scientist how is willing) and publishing in PLOS, but you didn’t answer.
Latitude
“Latitude says:
July 23, 2014 at 10:22 am
1. What are the best methods to bound our ignorance about sensitivity
2. what do those methods show.
3. what additional observations do we need to constrain the problem further.
================
1. (a) based on a temp history that is so wonky it changes every time there’s a new run…(b) and constantly producing new science that says all of the old science was wrong
False. the changes in the temp history are tiny and dont effect the end result in any material way.
Again, you can waste your time doing blog comments or actually do some work.
there is a reason why Steve Mc, Nic lewis, Anthony W, And Loehle get a hearing from folks.
they do work.
you write comments.
nobody cares about your comments. no one in power should listen to them.
you are wasting your time because you are not changing minds.
Nic Lewis.. he is doing something. Craig Lohle? doing something.
Imagine if you devoted your intelligence to doing work rather than merely commenting.
So the real science debate that people can join is this
1. What is the real temperature change?
2. what is the real change in forcing and how much of it is human caused.
====
1. what is the real temperature reconstruction/history?
2. (see #1)
@Steven Mosher says:July 23, 2014 at 9:43 am, re: “Instead they waste energy and time on peripheral issues.”
Mosher, you mean peripheral issues like policy’s based on crap science that is costing us a fortune. I suggest you try to imagine a little harder as to why these peripheral issues are important !
While it’s clear that nobody knows anything for sure it seems hard to imagine that increasing CO2(being a greenhouse gas) is not having some effect on the temperature of the earth.
The planet has gone from 280 ppm to 400 ppm since the Industrial Revolution.
It’s also hard to imagine that humans burning fossil fuels have not been responsible for some or even most of that increase.
Those that state that CO2 followed temperature in the past are probably correct but humans were not around in the past to add the CO2 first, so we have a different problem to solve this time, which is determining what happens to global temperatures when CO2 goes up first.
There has likely been some natural warming, which could have contributed to some of the increase in CO2 but the problem is still the same:
When CO2 goes up X amount, how much warming does it cause?
As time marches on, we get more points to plot on a graph of CO2 vs global temperature. Natural cycles can be seen effecting temperatures related to the oceans and sun and at least to my eyes, are pretty obvious(like those related to the PDO/AMO).
Knowing this, we should be able to at least estimate how much of a contribution other known factors effecting temperatures are/were making and use this to whittle down natural/other influences left with time.
As a result, we should be able to gradually get closer to having just the effect of CO2 on temperature.
If there is no effect, as some speculate, then that will come out only after we discover what natural cycle caused all the unaccounted for warming.`
Until then, we have to use the known science and facts, that includes CO2 being a greenhouse gas and large human emissions of it.
Modest warming so far has been beneficial and additional modest warming, if it were to occur would be mostly beneficial. Global cooling always creates greater hardship to life on this planet.
It blows my mind that the massive positive contributions of CO2 in the known law of photosynthesis take a back seat to modest, beneficial warming(that has been twisted and spun into catastrophic outcomes)
Sunshine +H2O +CO2 = Sugars(food) + O2
Increase the CO2 and you get more food and O2.
Explosive vegetative health, plant growth and world food production/crop yields have resulted.
nobody cares about your comments. no one in power should listen to them.
you are wasting your time because you are not changing minds.
====
And I’m so humbled you took the time to reply to them anyway………….
“False. the changes in the temp history are tiny and dont effect the end result in any material way.”
…that is the biggest load of BS, which one are you referring to….the one that has temp increasing?…the one that has temps flat?….or the one that show temps decreasing?..or the one that gets changed every time there’s a new run?
Newsflash, you are not the arbiter of what the “real science” debate is.
So why did they call Donna Laframboise who has not published anything?
http://www.parliament.uk/business/committees/committees-a-z/commons-select/energy-and-climate-change-committee/news/ipcc-ar5/
Your brilliant “logic” escapes me.
Right, because the skeptical influence in the Republican party that took control of the U.S. House of Representatives in 2010 and the repeal of a the carbon tax in Australia was all due to published science.
Mike Maguire, you write “When CO2 goes up X amount, how much warming does it cause?”
I keep on telling you. No-one, and I mean NO-ONE has the slightest idea, because no one can measure climate sensitivity.
What can be concluded from THIS ?
Tropics, the North Temperate and the South Temperate zones have 3 different CO2 sensitivities.
Surprising to find the South TZ much warmer than the North one, while Antarctic is much, much colder than the Arctic
Mi Cro, you write “but getting past this is beyond my ability (at least at this time) and available time.”
In other words, you haven’t the slightest idea. Why don’t you just agree with me that climate sensitivity CANNOT be measured?
Jim Cripwell commented
I know this is your White Whale, but there’s a difference between whether I think I can solve all of the issues in measuring it, vs whether I think it can be measured, which I do.