Do you agree that from 1995 to the present there has been no statistically-significant global warming
Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.
MIT Professor Richard Lindzen said something similar in a WUWT guest post:
There has been no warming since 1997 and no
statistically significant warming since 1995.
And, climatologist Pat Michaels said recently in an essay at The GWPF:
“The last ten years of the BEST data indeed show no statistically significant warming trend, no matter how you slice and dice them”. He adds: “Both records are in reasonable agreement about the length of time without a significant warming trend. In the CRU record it is 15.0 years. In the University of Alabama MSU it is 13.9, and in the Remote Sensing Systems version of the MSU it is 15.6 years. “
So with Dr. Ben Santer now solidly defining 17 years as the minimum to determine a climate signal, what happens to the argument when we reach 2013-2014 and there’s still no statistically significant upwards trend?
Separating signal and noise in climate warming
LIVERMORE, Calif. — In order to separate human-caused global warming from the “noise” of purely natural climate fluctuations, temperature records must be at least 17 years long, according to climate scientists.
To address criticism of the reliability of thermometer records of surface warming, Lawrence Livermore National Laboratory scientists analyzed satellite measurements of the temperature of the lower troposphere (the region of the atmosphere from the surface to roughly five miles above) and saw a clear signal of human-induced warming of the planet.
Satellite measurements of atmospheric temperature are made with microwave radiometers, and are completely independent of surface thermometer measurements. The satellite data indicate that the lower troposphere has warmed by roughly 0.9 degrees Fahrenheit since the beginning of satellite temperature records in 1979. This increase is entirely consistent with the warming of Earth’s surface estimated from thermometer records.
Recently, a number of global warming critics have focused attention on the behavior of Earth’s temperature since 1998. They have argued that there has been little or no warming over the last 10 to 12 years, and that computer models of the climate system are not capable of simulating such short “hiatus periods” when models are run with human-caused changes in greenhouse gases.
“Looking at a single, noisy 10-year period is cherry picking, and does not provide reliable information about the presence or absence of human effects on climate,” said Benjamin Santer, a climate scientist and lead author on an article in the Nov. 17 online edition of the Journal of Geophysical Research (Atmospheres).
Many scientific studies have identified a human “fingerprint” in observations of surface and lower tropospheric temperature changes. These detection and attribution studies look at long, multi-decade observational temperature records. Shorter periods generally have small signal to noise ratios, making it difficult to identify an anthropogenic signal with high statistical confidence, Santer said.
“In fingerprinting, we analyze longer, multi-decadal temperature records, and we beat down the large year-to-year temperature variability caused by purely natural phenomena (like El Niños and La Niñas). This makes it easier to identify a slowly-emerging signal arising from gradual, human-caused changes in atmospheric levels of greenhouse gases,” Santer said.
The LLNL-led research shows that climate models can and do simulate short, 10- to 12-year “hiatus periods” with minimal warming, even when the models are run with historical increases in greenhouse gases and sulfate aerosol particles. They find that tropospheric temperature records must be at least 17 years long to discriminate between internal climate noise and the signal of human-caused changes in the chemical composition of the atmosphere.
“One individual short-term trend doesn’t tell you much about long-term climate change,” Santer said. “A single decade of observational temperature data is inadequate for identifying a slowly evolving human-caused warming signal. In both the satellite observations and in computer models, short, 10-year tropospheric temperature trends are strongly influenced by the large noise of year-to-year climate variability.”
The research team is made up of Santer and Livermore colleagues Charles Doutriaux, Peter Caldwell, Peter Gleckler, Detelina Ivanova, and Karl Taylor, and includes collaborators from Remote Sensing Systems, the National Center for Atmospheric Research, the University of Colorado, the Canadian Centre for Climate Modeling and Analysis, the National Oceanic and Atmospheric Administration, the U.K. Meteorology Office Hadley Centre, and Lawrence Berkeley National Laboratory.
###
Source: http://www.llnl.gov/news/newsreleases/2011/Nov/NR-11-11-03.html
Anne M Stark, LLNL, (925) 422-9799, stark8@llnl.gov
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@ur momisugly R Gates:
“How would you have any “proof” that your home heater was working, other than to look at it running if the temperature in the home had stayed the same while you were gone? ”
Well, R Gates. You could stick your hand out and check an air vent or radiator – a signal.
Plonk.
Where is your signal ?
Matt G; I think you have it spot on. They cannot go longer than 17 years or logic will fundamentally undo them – Check Mate!
I find the debate on this topic odd . I mentioned earlier that in my opinion we don’t have to wait 17 years or 30 years to find out where our climate is going . It is not a statistical issue. In my opinion man generated Co2 plays a very minor role here.What is significant is the 10-15 years of flat and cooling temperatures in US that Anthony pointed out. It is not insignificant as some are trying to suggest . It may be so statistically but in reality it is a very vital clue. Just look at the NCDC Contiguous US Annual temperatures graph 1895-2011 which shows that Contiguous US is about where it was 10 years after the 1934 warming peak . There followed about 10-12 years of declining or flat temperatures[ like we just had ] which in turn was followed by 30 years of much colder temperatures from 1950 to 1980 [which is what may lie ahead for US for the next 30 years .] The natural ocean cycles are about the same as then[temperatures are starting to decline ] In my opinion we need to pay more attention to shorter climate trends and shorter than 17 years or 30 years that the statisticians may want . Ten years of flat and cooling tempertures are very significant in my judgement.
Nick in Vancouver said:
“Reality is complex and inconveniently unknowable.”
———
? Reality is unknowable ?
Let’s not get too far into Plato’s shadows on the cave wall analogies here, but we can know “reality” well enough to create very precise and complex machines that manipulate matter at the quantum levels, even recently teasing out photons from nothing in the fluctuations of space-time itself. Our standard model of particle physics may not be complete, and is, by definition, never going to be, but works well and proves every day that our model for the “reailty” that is behind this world we perceive is accurate enough a map to be powerful and useful.
Kaboom says:
November 17, 2011 at 12:20 pm
“The positive trend is quite close to the significance level. ”
Fuzzy isn’t part of mathematics.
######
you do a test for trend.
the trend is .2C
the 95% CI is .2C +- .21C
the positive trend is quite close to the 95% significance level.
Fuzzy is a part of statistics. statistics is a part of math.
figure out what that means logically.
And then we can talk about how incompleteness, randomness,and undecideability are at the heart of math.
“what happens to the argument when we reach 2013-2014 and there’s still no statistically significant upwards trend?”
We can know that from Prof. Will Steffan’s reply to Andrew Bolt last Sunday: they will say that surface temperature is not important – all the heat is being stored up in the oceans. Of course there is no direct measure of the heat stored in the oceans but, they no doubt will argue, where else could all that heat trapped by anthropogenic CO2 be going?
You can’t beat this logic!
RiHo08 says:
November 17, 2011 at 3:32 pm
Natural variation has currently dwarfed the climate changing CO2 signal.
_______
You are hugely missing the point and understanding what “natural variation” means in terms of climate, and the related issue of signal versus noise. Climate is not a random walk. There are always forcings that cause the climate to warm or cool. Why do you think so much time has been spent by climate scientists trying to pin down why there was a flattening of global temps over the past decade? If it was just “natural variation”, or random noise, why bother looking at all? Just throw up your hands and say it was random noise in the climate! ENSO cycles, solar variation, volcanoes, human aerosols, all represent elements in what some would simply lump together as “natural variation”. And in claiming that “natural variation” having “dwarfed” the CO2 signal, you are assuming you know the total sum and level of those other forcings, down to what they mean in terms of negative watts/meter squared of cooling (plus positive feedbacks)on a global scale and compare that total to the warming effect in watts/meter squared (plus feedbacks) of 390 ppm of CO2. It could be (and I even suspect it) that we’d be looking at a Dalton minimum cooling period over the next few decades were it not for the additional CO2, as that rather cool time frame (early 1800’s) saw a similar quiet sun a period of high atmospheric aersols from volcanic activity. Instead, we may get a period of flat global temps, as CO2 is simply masking those cooling effects.
Nick in Vancouver says:
November 17, 2011 at 4:13 pm
Mr Gates, you are making an assumption that “it”, the anthropogenic signal, is there in the first place. If you cannot see “it” over the last few years you then assume that you need more time to see “it”. Either way AGW as a theory has been falsified.
____
If your house is staying at 50 degrees, even though your heater is on, it doesn’t falsify the theory that the heat ought to be heating your house. It simply means that something else is negating the effect of the heater. Might want to check and see if the there are a few windows open somewhere…
See:
http://wattsupwiththat.com/2011/01/05/on-%E2%80%9Ctrap-speed-acc-and-the-snr/#more-30992
Gates ignores the fact that CO2 has been extremely low at times when the earth was considerably warmer, and CO2 has been extremely high during times of global glaciation. The only evidence of correlation between CO2 and temperature shows that rises in CO2 follow rises in temperature, on time scales of months to hundreds of millennia.
It is apparent that CO2 isn’t “masking” anything. That is just a convenient excuse to avoid the fact that the temperature has not been rising, as had been universally predicted by the alarmist crowd, from Hansen to Mann to Santer to Trenberth, and everyone else on that side of the AGW fence. The more evidence that comes in, the clearer it becomes that CO2 is a minor bit player; CO2 isn’t masking anything, the minuscule effect of CO2 is what is being masked by other much stronger forcings and feedbacks.
Who should we believe, planet earth, or R. Gates?
R. Gates says:
November 17, 2011 at 5:17 pm
It could be (and I even suspect it) that we’d be looking at a Dalton minimum cooling period over the next few decades were it not for the additional CO2, as that rather cool time frame (early 1800′s) saw a similar quiet sun a period of high atmospheric aersols from volcanic activity. Instead, we may get a period of flat global temps, as CO2 is simply masking those cooling effects.
Oh really? I thought fluctuations in solar activity were too small to cause discernible differences (circa IPCC)? Or is that except when convenient?
good grief….we’re talking 1/2 a degree
Heater on, open windows….my hootie
No one would even notice if it weren’t for all the hysterical bedwetting going on……………..
R. Gates says:
If your house is staying at 50 degrees, even though your heater is on, it doesn’t falsify the theory that the heat ought to be heating your house. It simply means that something else is negating the effect of the heater. Might want to check and see if the there are a few windows open somewhere…
In the “CAGW” concept then, wouldn’t the onus be on the CAGW supporters to show why the house isn’t getting any warmer?
Wouldn’t a complete understanding of what both warms and cools the house be required?
Just wondering.
R. Gates.
The question is “how much” is CO2 influencing temperatures. I am not aware there is any answer, speculative or otherwise. The CO2 signal has not been separated from the noise. You may have proof in your own mind, I just can’t find it in the scientific literature. I would be happy if you would provide a citation. I am happy to reject any statement that the current hiatus is like prior hiatus simply because the current levels of CO2 are claimed to be unprecedented and elevated. If the CO2 temperature connection were real, for the global atmosphere, then the CO2 signal could be identifiable; which to my knowledge has not been so identified. Observations trump speculative climate models. No way around it. I am happy to await the sudden CO2 related jump in global temperatures after all the natural influences dissipate. Are you willing to wait?
From R. Gates on November 17, 2011 at 5:17 pm:
Well now, isn’t that a creative way of flipping the issue onto its head. ‘The proof of human-caused global warming will be that the global cooling could be much worse.’
That ranks up there with the current sulfates/aerosols debate: ‘The sulfate-based anthropogenic global cooling signal is masking the anthropogenic global warming signal!’ Excuse me, but doesn’t all that stuff add up to a total anthropogenic signal?
Meanwhile, in regards to Phil Jones’ ‘not statistically-significant’ 1995 to present line, just at the beginning of this year there was debate here on WUWT that with 2010 on the books, the global warming is now statistically-significant, just needed that extra year. So, what happened with that?
R. Gates;
Tell me where I am in error>>>
Thanks for opening the door on that. Before I start the list, interesting to see, yet again, that you only seem to show up on threads where the work of one of “the Team” is being questioned. All sorts of highly technical threads, and nothing from R. Gates. But poke at Trenberth’s work, or Mann’s, or Santer’s and…PRESTO! there’s R. Gates to defend them. One can only wonder why that is… but I digress, you wanted to know where you have been in error. Glad to oblige.
1. You agreed to wager regarding Al Gore’s on air experiment in that if it was replicated as illustrated, whether or not it would show the results illustrated. You bet it would, and I bet it wouldn’t. Anthony replicated the experiment, and you were proven wrong. Then you tried to change what the bet was about. Then you claimed that all the experiment showed was that the glass in the jars absorbs infrared. In short, you lost the bet and won’t admit it.
2. During our discussion of the experiment, you suggested that the globes be taken out of the glass jars as they were superflous to the experiment. I have pointed out to you repeatedly that with no globes in the jars, there would be nothing to absorb short wave radiation and re-radiate as long wave radiation. Your suggestion that the globes were superflous demonstrates that you do not undestand the first thing about the physics of the so called greenhouse effect.
3. You claimed in another thread that the “models” have always shown the possibility of warming taking a hiatus. I’ve repeatedly asked you which of the 23 models cited in the IPCC AR4 report made this claim. I’ve asked you where in the IPCC reports this suggestion was ever made. You’ve not responded.
Oh, I’m sorry, you meant where you were in error in THIS thread. My mistake. OK, let’s tackle that.
1. You’re example of the house and the heater and the thermostat and the windows is all fine and good, seems like you understand what a propogation delay is and you are trying to articulate it. Unfortunately, that has absolutely nothing to do with determining what period of time is required for climate data to be statisticaly valid.
2. You said, and I quote:
“but mathematically, 17 years is the minimum to be able to statisically be able to see the anthropogenic warming signal among the noise”
This is simply a statement, it is neither evidence nor proof. In order for your statement to have merit, you would have to provide the mathematical analysis to show this to be the case. You have not done so anywhere in your rambling remark. A statement that cannot be substantiated is at best misleading, and most likely contrived. If you cannot produce the mathematical analysis to back your claim up, then you cannot assert that the mathematics says anything one way or the other.
4. One cannot help but miss the desperation in your comment to find some plausible explanation for the hiatus in warming that is consistent with the alarmism around CO2. Suddenly, after years of insisting that the temperature was increasing and that natural variability had nothing to do with it, apologists for the misrepresentation of science by “the Team” such as yourself are suddenly blaming the lack of warming on… natural variability. Well OK, you mentioned man made aerosols as well. I was watching an old re-run of the sit com “Barney Miller” recently, which was what, late 70’s? The character “Fish” comes walking through the door wheezing like he’s about to die. Asked if he is OK, he quipped “its the smog. I swallowed a piece”. Much of the rest of the show features the cops wrestling with the fall out from yet another “smog warning” in New York.
tell me please R. Gates, when was the last time that joke would have been relevant? How often does New York have smog warnings like they did in the 70’s? How about Los Angeles? Any major European city? The fact is R. Gates that what China is ramping up isn’t a fraction of what the west has cleaned up.
you’ve no excuses to explain the warming hiatus that don’t also explain the warming that came previously. In other words, your whole explanation is wrong. Again.
“…10-year tropospheric temperature trends are strongly influenced by the large noise of year-to-year climate variability.”
I had the impression that, according to warmists, there was not “natural variability” as warming was trending steadily upwards. Sometimes theses guys forget what other colleagues said…
Why stop at 17 years? Let’s go back 1000 and we see there hasn’t been any warming, we’re close to the same as then. Let’s go back 2000, oops, most likely warmer then than now. So what’s the emergency again?
“…we reach 2013-2014 and there’s still no statistically significant upwards trend?”
How do you know what 2013-14 temperatures will be?
R. Gates says:
November 17, 2011 at 5:17 pm
“Instead, we may get a period of flat global temps, as CO2 is simply masking those cooling effects.”
You had better be right. A Dalton Minimum occurring at the possible end of the Holocene? It is, after all, half a precession cycle old now. Five of the last 6 interglacials have each lasted about half a precession cycle……..
“Therefore in constructing the antithesis, and taking into consideration the precautionary principle, we are left to ponder if reducing CO2’s concentration in the late Holocene atmosphere might actually be the wrong thing to do.”
The Antithesis
http://wattsupwiththat.com/2010/12/30/the-antithesis/
@Kaboom November 17, 2011 at 12:20 pm:
There are plenty of people here that know a lot more about this than I do, but at the least I would say the following:
Actually, quantum physics is all about mathematics and fuzzy. They’ve turned physics into a statistical exercise, due somewhat to Heisenberg’s Uncertainty Principle.
And from what I know of cosmology and astronomy, there is a whole lot of whoop-ass fuzziness going on there. And math is what is telling them that there is, for example, dark matter and dark energy – about as fuzzy as you’re going to get.
If we go around thinking that math is all about non-fuzzy, yeah, in high school.
And ALL linear regression is about uncertainty. Look at any properly done graph of historical data, and the farther back in time you look, the uncertainty bands get wider and wider – as in fuzzier and fuzzier. Almost no linear regression can give anything more than a probability that a future value will be within some minimum and some maximum. That is pretty much a clear picture of fuzziness, if you ask me. No pun intended…
David Middleton says: November 17, 2011 at 12:57 pm
Tamino explains it all very well here…
http://tamino.wordpress.com/2011/01/21/phil-jones-was-wrong/
http://tamino.wordpress.com/2011/01/20/how-fast-is-earth-warming/
David provides two excellent links with respect to temperature trend measurement where an attempt is made to back out the effect of ENSO, volcanic eruptions etc. Both are well worth reading. Executive Summary: temperature continues to trend upward.
“In fingerprinting, we analyze longer, multi-decadal temperature records, and we beat down the large year-to-year temperature variability caused by purely natural phenomena…”
Ahhh…you gotta love Ben’s way of expressing himself…”we beat down” LOL!!
I wouldn’t give this guy the time of day…
William McClenney says:
November 17, 2011 at 7:37 pm
“Therefore in constructing the antithesis, and taking into consideration the precautionary principle, we are left to ponder if reducing CO2’s concentration in the late Holocene atmosphere might actually be the wrong thing to do.”
———
Not at all an unreasonable question. As I am not currently a believer in catastrophic AGW, it is certainly a question I’ve pondered. Additionally, as many WUWT readers have pointed out, even if AGW is happening (as I believe it is), there may be more significant environmental issues that need addressing that have nothing to do with how much carbon we are putting into the atmosphere.
“kadaka (KD Knoebel) says:
November 17, 2011 at 6:27 pm
Meanwhile, in regards to Phil Jones’ ‘not statistically-significant’ 1995 to present line, just at the beginning of this year there was debate here on WUWT that with 2010 on the books, the global warming is now statistically-significant, just needed that extra year. So, what happened with that?”
Professor Jones should never have said this because almost as soon as he said it, it was already irrelevant. The anomaly for 2009 was 0.443. The anomaly for 2010 was 0.477. However the anomaly for the first 9 months of 2011 so far is only 0.358. So it is simple to do the math for the average for the last 21 months, namely 12(0.477) + 9(0.358) all divided by 21 gives 0.426. This is LESS than the 2009 value of 0.443. So in other words, the warming for the last 16 years and 9 months is NOT significant at the 95% level. And when the figures are in for all of 2011, we will have 17 years of warming that is NOT significant at the 95% level. If you do not believe me, see the graphics at:
http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/
Focus on the top 95% error bar for 1995 and note that it is way above the bottom error bar for the presently green 2011 line. It is so much higher that the green line cannot catch up any more for the remainder of the year.