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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“davidmhoffer says:
November 17, 2011 at 6:46 pm
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 and R. Gates may be interested in the part below.
On a different post, this appeared. Very interesting!
BobM says:
November 17, 2011 at 9:02 am
Anthony, WUWT is also on my daily list. I’ve not posted any comments before but thought you might want to look at this: http://www.nyelabs.com/
Bill Nye admits “The Climate Project people created their own version, but apparently they didn’t test it very well. One of our strident climate change deniers seized on their corner cutting and showed their demonstration didn’t demonstrate anything.”
Most posts have missed an important concession by the Warmist authors: They admit the possibility of their models being wrong.
Prior to this, the Warmists and the IPCC have steadfastly clung to the (tenuous) claim that their plethora of models are infallible.
They just agreed to have the veracity of their models evaluated in about 4 years. Before, any attempt to examine or test their models were rebuked.
This is a very good sign that they are (subconsciously) admitting that they have lost any “high ground” they may have had, and are consenting to testing.
This implies that, deep down, they know that they have lost, and are hoping to stave-off the end-game for a few years, while they try to invent a new angle (spin) to again feed on Green Party largesse.
To delay the inevitable, they are doubling-down on their stupid bet lat CO2 is the climate’s forcing function.
Newt Love
Aerospace Technical Fellow of Modeling, Simulation, and Analysis
Great blog post and timely too. RSS data for 1996-2012 (17 years) shows no trend if one assumes a cold 2012. I’m sure Santer will rely on giss or some other dataset that gives him 5 more years, but this time next year will likely provide 17 years of no warming.
Santer (and R.Gates)…..the gift that keeps giving!
davidmhoffer says:
November 17, 2011 at 6:46 pm
David, I am not into basket ball but it is my understanding that your post would be referred to as a Slam Dunk? It is notable that he (R.Gates) is ignoring you again!
Be ever thoughtful of both facts and predictions before leaping to a conclusion. It was in fact a LEAP that terminated the last interglacial, the cold Late Eemian Aridity Pulse which lasted 468 years and ended with a precipitous drop into the Wisconsin ice age. And yes, we were indeed there. We had been on the stage as our stone-age selves about the same length of time during that interglacial that our civilizations have been during this one.
http://www.particle-analysis.info/LEAP_Nature__Sirocko+Seelos.pdf
So Santer has a 17 year itch … anybody know if he’s been to see a doctor?
In case you decide not to read it, here’s how it ends:
“The onset of the LEAP occurred within less than two decades (see the core photograph in Fig. 4), demonstrating the existence of a sharp threshold, which must be near 416Wm22, which is the 658N July insolation for 118 kyr BP (ref. 9). This value is only slightly below today’s value of 428Wm22. Insolation will remain at this level slightly above the inception for the next 4,000 years before it then increases again. Accordingly the model results predict a continuation of our present interglacial for the next 55 kyr (ref. 5), when insolation will decrease for the first time again to the LGI level. However, the Earthwill be in a fragile state for the whole of the next 4000 years, and one can only hope that the expected climate extremes of the Anthropocene will not lead to conditions that cross the threshold to glaciation.”
So, who can identify the human fingerprint in the latter curve? (except Dr. Santer)
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1945/plot/hadcrut3vgl/from:1975/to:2003
2011 is shaping up to be a cool year, at the bottom of the recent plateau, and 2012 looks to be even cooler. Once these two years are in the books, things will be more awkward for the warmists.
I read just yesterday, in the Guardian I think, some eejit saying that the idea of a pause in warming was nonsense – as proved by the fact that 2011 is looking to be one of the hottest 10 years on record!
Duh! If temps are flat for ten years after the hottest on record, isn’t it likely to be still somewhere close to the hottest year on record? Why is this so hard to grasp by the warmista?
Juraj V. says:
November 17, 2011 at 11:45 pm
So, who can identify the human fingerprint in the latter curve? (except Dr. Santer)
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1945/plot/hadcrut3vgl/from:1975/to:2003
Please Mr Gates, take up Juraj V on his request. While doing so be so kind as to further identify the period of 1948 to 1978, and show the human fingerprint there. Mr Gates, a keen but biased intellect can more readily assume an unbalanced position. The acronym for this is B.W.B.S. Your comments on this post are indeed more manure for the compost pile if you fail to respond to this query.
Can you find a mistake?
Simple equation calculates average global temperatures since 1895 (including the last 17 years) with accuracy of 88%. See it in the pdf made public 9/24/11 at http://climaterealists.com/index.php?tid=145&linkbox=true
R Gates,
“Wrong. Read the study before mouthing off.”
Forgive me for mouthing off – I mistakenly thought Anthony allowed freedom of speech on his blog, but obviously he must defer to a higher authority. Anyway, now that I’ve read the study, it all becomes clear – it was the model wot dunnit.
I can just picture old Ben with his screwdriver, tweaking the screw marked “time delay” until out pops a hiatus – of 17 years. “That’ll do” says Ben, and they all lived happily ever after. Any more fairy tales Gates?
From Santer’s paper, the climate models have the Satellite Lower Troposphere increasing at 0.23C per decade over the last 32 years.
The actual trend is 0.14C per decade (which would be closer to 0.10C per decade if one takes into account that two volcanoes early in the record made the trend higher than it would have been).
Santer 11 also says that once the Satellite trend gets below about 0.11C per decade, this will be a significant divergence. This could happen in a year or two if temperatures continue declining due to the La Nina (the La Nina might have to continue into 2012 to reach these numbers).
The 17 years, however, is really misdirection because the length of time required to prove significance is related to how far off the trends are to start with. 10 years would be more than enough if the satellites and real temperatures were showing -1.0C per decade for example.
Santer’s paper (below) is just a fine example of how just making up statistical formulae works perfectly well in climate science.
http://muenchow.cms.udel.edu/classes/MAST811/Santer2011.pdf
Hasn’t the stratosphere cooling been stopped for 17 years? What’s up with that, anyway?
Why, it has…
http://www.ncdc.noaa.gov/bams-state-of-the-climate/2009-time-series/stratosphere?del%5B%5D=hadat&del%5B%5D=iuk&del%5B%5D=raobcore&del%5B%5D=ratpac&del%5B%5D=rich
I only included satellite data, because the radiosonde data is shiesc, I think the word is.
Pete H;
It is notable that he (R.Gates) is ignoring you again!>>>
Well he’s kinda stuck now isn’t he? He’d look like a complete and total fool if he continues to argue his various positions, nor does he seem capable of simply admitting that he was flat out wrong. That leaves him with just one option which is to ignore me. I’m OK with that. It means I’m scoring points into an empty net.
And best of all, he hasn’t said boo about my observation that he only shows up in threads where people like Mann and Santer and Trenberth (especially Trenberth!) are being exposed or questioned in any way. Its almost like he’s got a job to do, so he grits his teeth and does the best he can with his limited tool set and hopes to collect whatever compensation it is that keeps him doing what he’s doing.
BWAHAHAHAHAHAHAHA!!!
It was natural variability in 1990.Then in 1995 it was a trace gas causing the warming.Then in 2001.It was a trace gas causing a developing catastrophic warming.Then in 2007 it was highly likely that it was us who is causing ALL the warming.
Throw in the numerous cherrypicking temperature trend complaints made by the warmists.The ones that might be 10 + years in length.But at the same time they and their common deceptive friend.The Media crow over a SINGLE weather even as proof of global warming (which never happened since 1979).
Now we have a man who may have started the corruption process in the IPCC.Comes up with a 17 year number.Since this will come back to haunt them and help further destroy their long dead AGW hypothesis.
Why bother continuing to make it so easy for rational people to laugh at you?
I didn’t see anyone mention this, so I will. Ben wants to establish the goal posts at 17 years? That’s fine. According to RSS…. in March of 2012 it will have been 15 years without any warming! http://www.woodfortrees.org/plot/rss/from:1997.25/plot/rss/from:1997.25/trend So, two more years? No problem. We’ve been at this game much longer than that. The clock is ticking. So, to the alarmists out there……. tick… tock….tick…….
I can certainly see why 17 years is the magic number needed to build a trend regarding the series of data used in the analysis. It is a statistical necessity in order to say that the trend is significant (IE outside the error bars). But a magic number says nothing about what is causing the trend. The trend is simply an average of weather pattern variations over the data series. It is not made up of “different” weather than the every day weather that is represented in the data. Weather data is a soup. Once it’s made, you can’t adequately remove and separate the stuff that made the soup, at least not in the data string discussed here. And the artificial trend line is even more “soup-like”.
The argument must stay focused on what causes changes in weather pattern variations. For that, the weather affects of natural short and long oscillations (which can be as short as two years and as long as 60+ years), and teleconnections between oscillations must be removed from the weather patterns observed. To do that we need a gold standard control period that is long enough to encompass these various oscillation patterns and that does not lay within the current CO2 rise. The long term recovery from the last ice age must be removed. And the even longer term axial tilt issue must be removed. I’m not worried about the Sun because that oscillation affects our ground temp very little (it is hard to get solar temperature affecting drivers through our atmospheric soup to any degree that could overtake the much stronger intrinsic drivers here on terra firma).
These important variables have not been presented strongly enough by AGW climate scientists. This glaring absence calls into question their hypothesis more than any other mistake they have made.
I should have also mentioned, if we were to use HadCrut……..we’ll have 15 years of cooling in June of next year. http://www.woodfortrees.org/plot/hadcrut3vgl/from:1997.5/plot/hadcrut3vgl/from:1997.5/trend ……. tick……..tock….
*****
William McClenney says:
November 17, 2011 at 10:53 pm
http://www.particle-analysis.info/LEAP_Nature__Sirocko+Seelos.pdf
*****
Thanks for the pdf — very interesting. Recommend it to everyone. Climate can & does change in mere decades. Makes our current warm, benign climate seem like paradise.
Ooh, he’s going to regret that – no later than 2015 I await a wuwt article with the title “Santer’s 17 years of cooling are here” 🙂
“Carl Chapman says:
November 17, 2011 at 12:12 pm
Why 17 years?”
My guess? Because the warming of the 80’s & 90’s was only significant over a 17 year period.
2013 News flash from AGW network.
Noise from 17 year Cicadian rythm drowns out statistically significant cooling trend. Scientists determine that 30 year trend required for statistically significant cooling, 5 years for warming.
Film at 11:00.
/sarc
The length of time needed to declare any cooling trend to be significant, will always be 2 to 3 years longer than the current cooling trend.