Lower climate sensitivity is getting some mainstream discussion. Last week at WUWT, we had this story: BREAKING: an encouraging admission of lower climate sensitivity by a ‘hockey team’ scientist, along with new problems for the IPCC which is now the most read story on WUWT in the past week.
This morning, WUWT carried this essay from Chip Knappenberger: The yearly lukewarm report which spurred some communication from Andrew Rekvin at NYT about the similar story he just posted today: A Closer Look at Moderating Views of Climate Sensitivity.
Andy just sent me a fascinating exchange from Gavin Schmidt of NASA and the Realcimate blog. Gavin sent sent this note as part of a group e-mail exchange and this is what Revkin forwared to me (and has now posted at Dot Earth):
Andy, I think you may be slightly misrepresenting where the ‘consensus’ on this issue has been. While there have been occasional papers that have shown a large tail, and some arguments that this is stubborn – particular from constraints based on the modern tranisent changes – there has always been substantial evidence to rule these out. Even going back to the 2-11deg C range found in the initial cpdn results in 2005, many people said immediately that the high end was untenable (for instance).
Indeed, the consensus statements in the IPCC reports have remained within the 1.5 – 4.5 range first set by Charney in 1979. James’ work has helped improve the quantifications of the paleo constraints (particular for the LGM), but these have been supported by work from Lorius et al (1991), Kohler et al (2010), etc. and therefore are not particularly radical.
By not reflecting that, you are implying that the wishful thinking of people like Ridley and Lindzen for a climate sensitivity of around 1 deg C is tenable. It is not, and James’ statement was simply alluding to that. For reference, James stated that his favored number was around 2.5 deg C, Jim Hansen in a recent letter to the WSJ quote 2.5-3.5 (based on the recent Palaeosens paper), and for what it’s worth the CMIP5 GISS models have sensitivities of 2.4 to 2.7 deg C. None of this is out of the mainstream.
I sent Schmidt and the group this reply:
In policy circles, including popular calculations of emissions trajectories necessary to avoid a high change of exceeding 2 degrees C. of warming, the hot tail has not been trimmed (unless I’m missing something?).
To me, that says the climate science community — including the Intergovernmental Panel on Climate Change science working group — has not adequately conveyed the reality you state here.
======================================================
Anthony: This essay from Pat Michaels is relevant also:
When “sensitivities” get below the “no-feedbacks” sensitivity of 1.2 then that will be a sign that the climate alarm hucksters are beginning to face reality. Convection is a cooling phenomenon with a negative feedback factor on surface heating, a fact which should be blatantly obvious to any qualified scientist. Time to stop the charade.
“Also, Gavin Schmidt is gabbin’ sh!t as per usual, since he was riding the 3+ train hard until just recently.”
It’s like how some leaders in the Mideast will release one version of a statement in Arabic and another in English, each telling the audience what it wants to hear, often in direct contradiction.
“Isn’t it possible that [the first day] could have been 25 hours? It could have been 30 hours, could have been a week, could have been a month, could have been a year, could have been 100 years, or it could have been ten million years!” – Spencer Tracy in Inherit the Wind.
“Isn’t it possible that [climate sensitivity] could be less than 3 degrees? It could be less than 2.5 degrees with solar influences, could be less than 2 with black carbon, could be less than 1.5 as the years pass with no warming, could be less than 1, could be less than 0.5, could be nothing at all!” – future movie with an alarmist of your choice getting pummelled in a courtroom.
If one is to believe to the Hansens past and present pronouncements , one could conclude that CO2 saved the globe from another Little Ice Age, widely predicted in the late sixties and early seventies, and all due to the CO2 sensitivity of 2, as I demonstrate effortlessly here:
http://www.vukcevic.talktalk.net/00f.htm
🙂
I smell rats trying to leave the sinking ship in an orderly fashion. They know even the “low” 2 degree is [unsupported] by the evidence. I bet it’s maximum 1.5 and could be lower then 1 at the point where we are now.
I have to say though, after reading his blog I quite like this Annan fellow. If only he had Hansen’s job.
Kev in UK.
Let me explain why it cannot be negative.
Definitions:
Sensitivity: the change in temperature per change in Watts.
So, for example if the sun increases by 1 watt, and the earth warms by 1 watt you have a
sensitivity of 1. If the sun goes up by 5 watts and the earth warms by 1 C you have 1/5 or
a sensitivity of .2
By studying the relaxation response to volcanos, for example, you can estimate this to be
lets say .7 +- .3 or .4 to 1. ( just for example ). Note that this estimate has nothing to do
with C02. it describes how the system responds to forcing. This is all definitional work.
More watts = higher C.
The next step is to calculate how many additional watts an increase of C02 will cause.
This is straightforward using known, tested, verified physics.
Watts = 5.35ln(x/y) where x is the concentration after change and y is before the change.
For doubling c02 from pre industrial to today you get around 3.7 watts.
So. If your estimate was .5 for sensitivity ( from your volcano study for example ) you
can then say that doubling C02 from pre industrial to today will get you 3.7* .5 or 1.85C
you cant get negative values unless you deny that c02 blocks IR. Since C02 does block IR, it is a positive forcing.
Steven Mosher says (February 4, 2013 at 11:29 am)
—
(1) The Snowball Earth is a hypothesis.
(2) CO2 concentration posited to exit it has been estimated at 130,000 ppm.
It’s a bit of a stretch to use this as a constraint on sensitivity now.
How does Gavin’s claim “Indeed, the consensus statements in the IPCC reports have remained within the 1.5 – 4.5 range ”
relate to this from IPCC Fourth Assessment Report: Climate Change 2007?
“Since the TAR, the levels of scientific understanding and confidence in quantitative estimates of equilibrium climate sensitivity have increased substantially. Basing our assessment on a combination of several independent lines of evidence, as summarised in Box 10.2 Figures 1 and 2, including observed climate change and the strength of known feedbacks simulated in GCMs, we conclude that the global mean equilibrium warming for doubling CO2, or ‘equilibrium climate sensitivity’, is likely to lie in the range 2°C to 4.5°C, with a most likely value of about 3°C. Equilibrium climate sensitivity is very likely larger than 1.5°C. ”
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch10s10-5.html
Seems to me we’ve been over this ground with the Nic Lewis analysis done last December.
Sorry Steve, had to pop out for a while.
re climate sensitivity – I am referring to it only in relation to CO2 – which is what I thought was usually meant by the figures bounded about? Have I got that wrong? (I am fully aware that it is a generic term for forcing – but in the climate debate it seems exclusively reserved for forcing from CO2). So, in this context, high CS means a large effect from CO2, yes? Low CS means little effect from CO2? By negative, sure – it probably isn’t negative, but it is feasibly as close to 1 as makes it negligible.
re considering forcing from volcanoes, that’s surely comparing apples to oranges in any case? You cannot mix one type of forcing with another IMHO, as the nature of the forcing ‘action’ is different, for any number of reasons, distribution, height in the atmosphere, etc, etc. e.g cloud forcing from high clouds is not the same as cloud forcing from low clouds. My understanding of the CO2 forcing, is that it is an assumed value in all the climate models, and is usually a high value. This is shown clearly wrong from the predictive models themselves!
as for the denying CO2 blocks IR – the experimental work is not the same as the atmosphere (IMHO) – and if you cant have a snowball earth (which as Cui bono correctly says – is a hypothesis anyway) then you equally can’t have earth recovering from the hot temps and high CO2 of the past!
As a geologist I have to stand back and say the CO2 theory for past, present and future warming cannot be reconciled with the geological record, ice cores, etc….
Steven Mosher says:
February 4, 2013 at 10:50 am
So…for us beginners…does Gavin think there is a possibility the correct number is less than 2.0 already?
yes. the only people who are certain about the number are the people who think it is certainly below 1
——————————————-
This is another disturbing misrepresentation.
AR4 mainstream position was:
“Equilibrium climate sensitivity is likely to be in the range 2°C to 4.5°C with a most likely value of about 3°C, based upon multiple observational and modelling constraints. It is very unlikely to be less than 1.5°C.”
Lindzen, Spencer and others who computed sensitivites below 1 never expressed certainty and to my knowledge not even likelyhood to the level of the IPCC
cui bono says:
February 4, 2013 at 11:42 am
“Steven Mosher says (February 4, 2013 at 11:29 am)
—
(1) The Snowball Earth is a hypothesis.
(2) CO2 concentration posited to exit it has been estimated at 130,000 ppm.
It’s a bit of a stretch to use this as a constraint on sensitivity now.”
You fail to understand Mosher. Hypotheses, aka guesses, from CAGW proponents of the consensus count as tested and verified empirical evidence. To him it is all one grand, beautiful narrative that should not be addressed on a hypothesis by hypothesis basis by critics. To do so is to speak with the vulgar.
Mosh
I don’t think you can get a 2.5 to 3.5 C climate sensitivity from CO2 from Palaeo evidence unless you assume a large part of the temperature change comming out of the LGM is due to CO2. The evidence that CO2 is the primary or even one of the primary drivers is not entirely convincing.
Steve Mosher, ” The lag has nothing to do with it. The lag was predicted before it was discovered and is what one would expect if AGW is true.”
Do you have a link or two for this?
Steven Mosher says:
Nope.cant be less than 1 or you cant get out of an iceball earth.
————————————–
I think you mean “negative” and not “less than 1”, because less than one is perfectly possible with a solar amplifier and/or exaggerated temperature trends and/or unknown internal climate forcings.
Steve Mosher, ” Watts = 5.35ln(x/y) where x is the concentration after change and y is before the change.”
X and Y are CO2 concentrations. Since on a molecule for molecule basis, CH4 is ~30 more potent than CO2 (potency=ability to absorb IR, nothing do do with quantity), the same equation cannot be true for CH4, right?
The problem here, isn’t that they were wrong about the sensitivity. Scientists are wrong all the time. The problem is that admitting they were wrong would be politically disastrous. Because CAGW was sold to the wider world on the basis, ‘scientists say this and scientists are always right’.
Otherwise, Gavin is well aware that differences in output from the climate models are just quantified differences in the opinions of the modellers. And the opinions of scientists are only science when they derive from well articulated and falsifiable theories. If they derive from theory, then clearly there is no consensus. If not, then they are just numbers picked out of the air.
And don’t let Mosher mislead you. Sensitivity is net of feedbacks, and we know almost nothing about feedbacks over all timescales.
“Nope.cant be less than 1 or you cant get out of an iceball earth.”
Yet Earth has emerged from ice ages where CO2 levels dropped. Try again.
Kev-in-Uk says:
February 4, 2013 at 10:29 am
Seriously though – the lower range in the first graph looks far more realistic and that is based purely on the fact that earth today ‘may’ have warmed by around 0.5degC since the industrial revolution (and I am not 100 percent convinced of that, due to the vagaries of the station record, etc).
Proff. Peter Cox below, shows his climate model with CO2 forcing excluded, green line.
Second graph graph shows tree ring study
http://s446.beta.photobucket.com/user/bobclive/media/attenborough_zps1fdbe055.jpg.html?sort=6&o=0
http://s446.beta.photobucket.com/user/bobclive/media/800px-Briffa-tree_ring_density_vs_temperature_1880-2000_zps39423dee.jpg.html?sort=6&o=1
The model without CO2 forcing appears to agree with the tree ring data. does that indicate CO2 forcing is insignificant.
UNEP state,
It is now thought, is that atmospheric carbon dioxide levels have reached levels which are affecting tree growth.
Carbon dioxide acts as a fertiliser to many tree species, making gas concentrations beyond a certain level uncouple the relationship between temperature and tree growth.
Has there been any substantial temperature rise since the 60`s and I thought trees grew more
vigorously with increased CO2.
Can someone explain.
Anthony Watts says:
February 4, 2013 at 11:34 am
You stole my thunder. There is no reason that the sensitivity would be linear. So, it can heat things up initially, and then lose its potency as an equilibrium with all the other processes going on is established.
Steven Mosher says:
February 4, 2013 at 11:42 am
See above. As the usual disclaimer goes, all things being equal, more CO2 should heat the Earth. But, all things are not equal. Thanks anyway for foregoing your usual driveby style.
@Bill Illis
“I have my own version of the above chart which shows where the actual observations to date are and that which takes into account Gavin’s comment about the transient warming timeline.”
How different would the data be if charted unadjusted?
Steven Mosher says:
February 4, 2013 at 11:29 am
“Nope.cant be less than 1 or you cant get out of an iceball earth”
Steve, tell me then, if the earths warm temps depend so much on CO2 concentration, how come the earth didnt turn into a snowball when recently CO2 was closing in on 200ppm??
.If you dont need CO2 to stay warm, then maybe you DONT need CO2 to get warm.
We can always hope the day comes when Mosher reads about unknown unknowns … until then we will probably have to put up with his proclamations.
As for Gavin and company all we need is logic. It is well known that research bias is a given. We all know that the warmists runs climate change research. Hence, it is almost 100% certain that the research is biased to have a higher sensitivity than reality. Every time we see a trimming of the sensitivity we can still be assured they are biased on the warm side.
From this logical viewpoint only it’s looking more and more like the the sensitivity is much less than 2.
Steven Mosher says:
February 4, 2013 at 11:42 am
I see large problems with this interpretation:
1. Climate sensitivity is an inversely proportional function of temperature for several reasons.
• Radiation is a function of T^4.
• Parasitic losses increase with temperature.
• Emergent cooling mechanisms (thunderstorms, dust devils, rain) are temperature based with high numbers above a threshold of emergence.
Clearly, climate sensitivity is inversely proportional to temperature, falling as temperature rises.
2. Climate sensitivity varies over both space and time. In the early morning in the all-critical tropics where the energy enters the planet-sized heat engine we call “climate”, the temperature rises rapidly because of the lack of clouds—a high change in temperature per change in watts (high sensitivity). In the late morning the watts are still rising but the clouds greatly reduce the temperature rise—smaller change in temperature per change in watts (low sensitivity). And indeed, certain areas at certain times can show negative sensitivity, and some areas of the planet are not sensitive to the forcing at all.
Now, the global average climate sensitivity that Steven is discussing is no more than the average of these highly varying sensitivities. But the average is greatly misleading, because it is taken as constant or semi-constant. In the real world, however, climate sensitivity not constant in any sense. It is both inversely proportional to temperature and highly non-linear.
As a result you can’t just say well, because the global average surface temperature doesn’t vary much, we can treat it as a constant. The average is not real, it is a mathematical chimera. In the real world, we don’t see an average temperature. If the “average temperature” goes up by one degree, and it happens to be evenly spread out, let’s say the morning temperature goes from say 7°C to 8°C, while the afternoon goes from 22°C to 23°C.
But both the climate sensitivity, and the change in climate sensitivity with temperature, are very, very different in the two temperature regimes of morning and afternoon. It takes much, much more energy to go from 22°C to 23°C than it does to go from 7°C to 8°C. So while the average temperature doesn’t change much, that is highly deceptive. In reality, the dependence of sensitivity on temperature makes a huge difference in how the system actually reacts to changes in forcing.
Regards to all,
w.