New Research Finds Earth Even Less Sensitive To CO2 Than Previously Thought

As first reported on WUWT yesterday via our in-flight news office over the Atlantic, climate sensitivity is now seen to be even less, thanks to the new peer reviewed paper from Nic Lewis and Judith Curry. This press release comes today via The GWPF.

Research Used Data From This Year’s IPCC 5th Assessment Report

London, 25 September: A new paper published in the prestigious journal Climate Dynamics find that the effect of carbon dioxide emissions on global temperatures is likely to be even smaller than previously thought.

Earlier this year, in a widely discussed report for the Global Warming Policy Foundation, climate researcher Nic Lewis and science writer Marcel Crok put forward a new estimate of the Earth’s climate sensitivity based on observational data, finding that it was much less alarming than suggested by computer simulations of the Earth’s climate.

Now, Lewis and well known American climate science professor Judith Curry have updated the Lewis and Crok report estimates using the latest empirical data, a more sophisticated methodology and an approach to accounting for uncertainties that has been described by one independent reviewer as “state of the art”. Their findings fully support the modest estimates of climate sensitivity and future warming given in the Lewis and Crok report, and compared with that report make it look even less likely that the substantially higher estimates based on computer simulations are correct.

“Our results, which use data from this year’s IPCC fifth assessment report, are in line with those of several recent studies based on observed centennial warming and strongly suggest complex global climate models used for warming projections are oversensitive to carbon dioxide concentrations,” said Nic Lewis.

Lewis-Curry_article_table1

Best sensitivity estimates are medians (50% probability points). Ranges are to the nearest 0.05°C

Nicholas Lewis & Judith A. Curry (2014) The implications for climate sensitivity of AR5 forcing and heat uptake estimates, Climate Dynamics 25 September 2014

Abstract

Energy budget estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) are derived using the comprehensive 1750–2011 time series and the uncertainty ranges for forcing components provided in the Intergovernmental Panel on Climate Change Fifth Assessment Working Group I Report, along with its estimates of heat accumulation in the climate system.

The resulting estimates are less dependent on global climate models and allow more realistically for forcing uncertainties than similar estimates based on forcings diagnosed from simulations by such models. Base and final periods are selected that have well matched volcanic activity and influence from internal variability. Using 1859–1882 for the base period and 1995–2011 for the final period, thus avoiding major volcanic activity, median estimates are derived for ECS of 1.64 K and for TCR of 1.33 K. ECS 17–83 and 5–95 % uncertainty ranges are 1.25–2.45 and 1.05–4.05 K; the corresponding TCR ranges are 1.05–1.80 and 0.90–2.50 K. Results using alternative well-matched base and final periods provide similar best estimates but give wider uncertainty ranges, principally reflecting smaller changes in average forcing. Uncertainty in aerosol forcing is the dominant contribution to the ECS and TCR uncertainty ranges.

fig2_ecs_tcr-bcs3-vol1a

Full paper of the accepted manuscript is available, along with data and code here

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Dave Peters
September 26, 2014 12:27 pm

WUWT-ers: You may freely assume that I am a hiatus-denier, and arrive here from drastic navigation error, obviously (tho please in the name of God, do not place me in bed with Amory Lovins or the “Green Agenda”). My query was prompted up thread, but I would appreciate anyone’s straightening me out.
Steven Mosher — I gave some time to an abbreviated attempt to follow the exchange between Schmidt & Curry, RC and Cli..Etc., in past weeks, but will require greater effort to get my arms around it, if I am even equipped to ever grok things at the level of their interplay. Your post upthread 12:16 pm of the 25th intrigues me. You state:
“The method computes a difference in Forcing between two period(s). 1859 –1882, 1995—2011.”
I apologize for the length of my insertion below, as it is taken from a dialogue I am conducting on Andromeda. But the question is raised, why the pre-Krakatoah cut off? And why the ’97 El Nino INCLUSION? After all, Pinatubo reduced H2O by ~20 times the model predicted delta-T, in percentage terms, and vapor responds quickly to temps.
[insertion from other thread:
1996 – 2000: .. 32 ,,, 71 … 96 … 55 … 53
1999 – 2013: .. 89 … 98 … 73 … 81 … 88
Re: Lynn, XXX asking about responding to the “hiatus / pause” claim.
Why is it, that 97% of seven year olds have no difficulty identifying the bottom data string as “bigger,” while opinion and professional engineering journal comment threads are loaded with folks who made it over the hump of Methods of Integration, and profess advanced degrees in quantitative disciplines, yet have emotionally dug in on the notion that those data demonstrate the absence of warming for those intervening 15 years? (The “units” above, are akin to “cents”, as we depict the HadCRUT4 surface thermometer measurements in the degrees of Fahrenheit, for the same reason Honda salesmen don’t list their new cars in yen, and things will be more familiar to the common folk if we consider a single such F. degree as one buck,)
Now, you’ve got your Apple-lovers (aka: warmists or hysterics) who seek to discern the “signal” of combustion’s consequence in warming a planet between 2/3rds & 3/4ths covered by oceans whose mixed layer is some ten times as massive as its air. Because, a quarter millennium ago Watt gave its people steam power so that coal could be mined for warmth and wrangling iron, a century and a half ago Rockefeller standardized oil to give them lamp light and then mobility, and a century or so ago Edison gave them electricity. And the question is, do these fabulous gifts impose a burden upon our descendants, a century or more off into the future?
The Apple-lovers point out that that 32 cent value for 1996 measures the warmth signal, as an anomaly when compared with a 30 year interval which concluded only six years earlier. And that were one to slide this reference window backwards in time, so as to figure out just how much total warming we have already achieved to date, it would just attain equipoise, with mid-point in 1907. If one were to slide the reference window any further back in time, it stops getting cooler and in fact starts getting warmer again, maybe all the way back to when Plato communed with Socrates, and Jesus trod the route to Jerusalem. Or maybe half that long. In any case, most evidence we tease from paleo-inferences indicates that temperatures fluctuated between a tenth or twentieth as fast, in preceding centuries, as they do in that first Carbon Century, once fossil fed fire got roaring, big-time.. And warmists draw the inference that the obvious explanation for the great inflection that creates that transposed checkmark pattern in our millennium-scale thermal record, is this appearance of such consequential combustion, and attendant exhaust. Further, enough thermometers were around to confidently measure the moment when this iconic hockey stick’s handle-era is joined with its blade-era. And it measures 66 cents worth.
We now have the “signal” of the true Apple, in hand. Big Apples, from before the warming hiatus set in, are measured by the average from the first string above, which is 61.3 cents. The sum from 1907 is 61 + 66 = $1.27, and it took 91 years, so big ones are a penny and four tenths, per year. Little Apples are measured by including the pause, and are found to measure a penny and a half each year. Wait a minute. They got bigger during the pause? Well, no matter, an Apple is the signal, and it is near a penny and a half each year. Each year the people keep digging up coal and drilling up oil and gas and burning it, and each year, on average, the world, since 1907, has warmed by half more than a hundredth degree Fahrenheit.
Orange-lovers (aka minimalists, luke-warmers, & deniers) are an entirely different breed, obviously. They absolutely hate this “signal” and all it stands for. Hence, they delight in finding noise. You can tell this about the Orangers, because they all flutter about one particular bit of noise, moths about a flame style, but we’ll look at that up close in a minute. An obvious source of natural variation could come from our sun, since if it sneezed or snoozed, we’d either fry or freeze. But though it does vary across an eleven year cycle, it only dims by a tenth of a percent while cycling, so it’s signal in our thermal trace is lost in other noise. Not noise itself. Volcanoes are noisy, and the biggie in the instrumental era was 1883’s Krakatoah. By annual global averages, it cost forty cents for a few years, though Bradley (yep, the MBH one, about ten years before he teamed up with Dr. Mann) found that it depressed summer temps in our hemisphere by a whopping $2.20, one summer. Orange lovers however don’t seem much interested in nature cool—they favor natural warmth. So, the oceans, unless they practice cold fusion on the sly, can’t “make” energy. About the most they can do is store it up from somewhere, and selectively cycle it to the atmosphere, when they are so moved. And they are good at it and do so in sundry patterns. El Nino is one such rhythm, and we’ve had about twenty since 1950, mostly dime-ante stuff. Exclusive of the event registered as such a standout by that upper data string above, 17 Ninos have averaged a bit less than 17 cents each. The name derives from baby Christ, because Peruvian fishermen observed the oscillation to appear most frequently in late December. The late nineties event not only piled up nearly forty-cents worth of heat gain in late 1997, the carry over into the new year boosted the Earth’s temperature by an added quarter across 1998. Sixty-four cents. In its most powerful twelve months, running from September of ’97 thru August of ’08, El Nino Grande added, year over year, both a half dollar and a nickel to the Hadley trace.
Back to the big question: Is it fair to future generations, to look for, select, and stand upon that most extraordinary moment, Grande being about a Krakatoah and a half only reversed in sign, and to peer out towards posterity with the inevitable aftermath of such a fleeting, cyclical phenomenon occupying the foreground? For if Apple-lovers count their penny and a half each year, for some periods maybe 3 cents for decades, and for others near nothing for a few decades, but the Orange-lovers employ a heat spike nearly forty times as large, what can be expected other than that decades might elapse, before enough Apples can be accumulated to match their one Orange? Yet in seven of the most recent twelve months, that is precisely what the globe has done. True, the Earth has not warmed, relative to that absurdly placed challenge of a sudden, forty-fold spurt, but it HAS equaled that mark, and in only fifteen years. Far from a pause, this can only result from an acceleration of the annual heat gain, relative to that of our entire history with warming. Orange-lovers are quite correct, however, that relative to the final couple decades of Century Twenty, the heat gain has diminished—but that gets into cherries, and is a whole other fruit best left for another day.
There is one final comment that cannot wait. Many Orange-lovers have a keen comprehension of the implications for humanity, of attempting to turn its back upon the sundry gifts which are gained with combustion. The intensity of this conviction animates the search through which they found their Orange, their El Nino Grande. To assume that they participate in the dialogue with unfeeling hearts, with non-relevant experiences, or with corrupted minds, or to assume that their concern with humanity either now or in the deep future is in any way of a lesser nature, does both them and the dialogue itself great, great disservice. ]

Andyj
September 29, 2014 4:18 pm

A quick run of the MODTRAN calculator shows us doubling CO2 shows a 2.78 Centigrade rise. What the calculation ignores is night time. So halve it and what do we get… 1.39 Centigrade.. Am I close enough when we consider the height of the stratosphere giving a shorter night will up that number around an eighth to around 1.6 Centigrade per doubling? 😉

Reply to  Andyj
September 30, 2014 6:01 am

When I point an IR Thermometer straight up (N41,W81) most days it’s below -30F (clear sky, Dew Pnt ~50 will get you near -50F temp) . It changes with dew point.
Now can MODTRAN calculate what I should be able to actual measure?
So my thermometer is rated to -60F from 8-14u, so you’d have to add the Co2 signal in 14-16u to get a total. ~3 w/m2, would increase the temp by as much as 4 F at about -40 F. I routinely see clear sky temps that are 70-100F colder than my concrete sidewalk (more than 4-5 hours after it’s out of the Sun).
Clouds are much closer to surface temps. It seems to me that a slight change in the BB temp of the sky as seen from the surface of the earth, is many many times smaller than the variation caused by clouds.