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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Lets not get lost in all this statistics . If the puropose of collecting all this climate data is to make better weather forecasts for the near term first, then waiting for 1 7 years or 30 years to tell the public that the climate cooled or warmed has little value . I see much greater value to the public in more accurately recording and predicting better shorter term and better regional forecats , like seasonal numbers , annual numbers and decadal numbers. Kowledge about short term trends is more imprtant in our daily lives than knowing what the climate will be when none of us will be around . The fact that US has not warmed for 10-15 years is important and we should not wait another 15 [to reachl 30 years ] before we comment publically.It has taken nearly 15 years for the AGW climate scientists to tell the public what is happening and then they cannot even agree what happened , but they claim accuarcy 100 years and some have even tried 1000 years
Think beyond trend lines and other polynomial curve fitting with no predictive ability.
A simple equation based on the physical phenomena involved, with inputs of only sunspot number and ppmv CO2, calculates the average global temperatures (agt) since 1895 (that’s 115 years and counting) with 88.4% accuracy (an insignificantly lower 87.9% if CO2 is assumed to have no influence).
The equation, links to the source data, an eye-opening graph of the results and how they are derived are in the pdfs at http://climaterealists.com/index.php?tid=145&linkbox=true (see especially the pdfs made public on 4/10/10, 3/10/11 and 9/24/11).
As shown in the 9/24/11 pdf, the equation accurately predicted the temperature trends for the last 20 years.
The future average global temperature trend that this equation calculates is down. The huge effective thermal capacitance of the oceans (about 30 times everything else) will cause the decline to be only about 0.13°C per decade. The decline may be as much as 0.22°C per decade if the sun goes really quiet.
R Gates,
“but mathematically, 17 years is the minimum to be able to statisically be able to see the anthropogenic warming signal among the noise”
Oh come on. This 17 years is just a made up number to buy a few years more time. “Mathematically” indeed!
Given that even warmists concede that an anthropomorphic climate signal is so weak that it takes decades to be identified and quantified, doesn’t this rather undermine the catastrophic tipping point thesis?
“This makes it easier to identify a slowly-emerging signal arising from gradual, human-caused changes in atmospheric levels of greenhouse gases,” Santer said.”
It’s a slowly-emerging signal now is it, this AGW? Only last week they were shouting about unprecedented rates of warming. It’s funny, this AGW theory. It’s the only theory in science that morphs into a different shape every time it conflicts with real data.
Ben Santer eh? I think this is an opportune time to remind WUWT readers who this Ben Santer is.
The notorious chapter 8 of the 1995 IPCC report included the claim that there was “A discernable human influence on climate.” This claim was added to the report AFTER the meeting of the drafting scientists in Madrid Spain.
Who added the claim? Ben santer.
Where did he get the notion of a discernable human influence? From his own paper which wasn’t even published yet. And in that paper he profoundly cherry picked a time frame of data from sonde balloons.
The full explanation and graphs are at the below link.
http://www.john-daly.com/sonde.htm
This man has the cheek to claim sceptics cherry pick.
OK – let’s look at the past 17 years. (using the satellite figures as it covers the whole planet not just the land)
http://www.woodfortrees.org/plot/uah/from:1994/plot/uah/from:1994/trend
A warming trend of 0.14 per decade or 1.4C over the Century. Nothing significant and not even close to the computer predictions.
R. Gates says:
November 17, 2011 at 12:53 pm
Gates do you actually believe what you wrote? Do you? really do you?
Ben Santer’s trying to delay that Senate inquiry freight train as long as he possibly can.
R. Gates…is it difficult trying to justify a lack of warming with a cartload of technogarbage? How’s that consensus holding up?
Vince Causey says:
November 17, 2011 at 1:59 pm
R Gates,
“but mathematically, 17 years is the minimum to be able to statisically be able to see the anthropogenic warming signal among the noise”
Oh come on. This 17 years is just a made up number to buy a few years more time. “Mathematically” indeed!
———–
Wrong. Read the study before mouthing off.
Baa Humbug says:
November 17, 2011 at 2:12 pm
R. Gates says:
November 17, 2011 at 12:53 pm
Gates do you actually believe what you wrote? Do you? really do you?
———-
Tell me where I am in error, and why I shouldn’t.
The most important aspect of this press release is to identify at least six people to arrest and prosecute for fraud and theft of taxpayer funding immediately, and a whole host of others to begin to investigate for prosecutorial purposes in the long run. It will require that the statutes of limitation be extended to 17 years to bag them all. There’s an entirely new career path for aspiring tort lawyers.
“A single decade of observational temperature data is inadequate for identifying a slowly evolving human-caused warming signal”
“by roughly 0.9 degrees Fahrenheit since the beginning of satellite temperature records in 1979”
=============================================================
A full 1/3 of the record shows cooling…..
……and for the math challenged, 17 years is a little more than 1/2 the record, and almost all of that neutral or cooling
Obviously, 30 years is not what they want to see either……….
Climate scientists have argued that satellites have confirmed that the radiation spectrum is showing an increase in energy absorption in the CO2 bands over this period, and that the atmosphere is therefore “trapping” more energy, can they explain where the energy is being diverted to, since it isn’t warming the atmosphere. Claiming that a natural cycle is at play is fine, but the energy is either being held in a large reservoir (which noone has detected or measured any changes in) or it is being expelled from the Earth (and again it appears noone has detected any change). So where is the energy being held since it isn’t showing up in the atmosphere?
I’d argue that the “missing heat” needs to be found or the basic assumption that more energy is being trapped needs to be revisited.
A year or two ago the Skeptic commentary on WUWT and other skeptical orientated blogs were very defensive of the skeptical arguments regarding the source of the so called AGW and the skepticism that increasing anthropogenic CO2 was the cause of any significant global warming.
In the last year or so and particularly when i read the comments above, the Skeptic commentary has become increasingly derisory of the ever shriller and ever more desperate fear mongering claims of, and to use Richard Bett of the UKMet’s definition, the “climate change scientists” and the self promoting green climate change activists.
Skeptics have recently become increasingly cynical about the suspected and gross ulterior motives driving the claims of so many of the “climate change scientists”, and the shrill howls of outrage from the green lobby as their lavishly funded pet climate projects fall away as a jaded public turn their backs onto their increasingly desperate attempts to install a permanent “climate fear” psychology into the public psyche.
Within the last year the Skeptics have seen an increasing volume of evidence, including much more science based evidence plus ever more extreme quotes from warmists and the green climate activists plus an increasing volume of anti warmist anecdotal evidence from numerous sources to back up and reinforce their skeptiscm.
What a difference a year makes!
And Consensus!
What consensus??
Haven’t heard that word for quite a while now.
Baa Humbug says:
November 17, 2011 at 2:12 pm
R. Gates says:
November 17, 2011 at 12:53 pm
Gates do you actually believe what you wrote? Do you? really do you?
==========================================
Of course he does….
He believes that it would have been a lot colder, if it weren’t for “A” global warming….
…so cold, it would have erased all traces of “A” global warming
…and the temperature would be below where it was when we started
😉
“See phil Jones’ interview:
http://news.bbc.co.uk/2/hi/science/nature/8511670.stm
A – Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical?
So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other.
Here are the trends and significances for each period:
Period Length Trend
(Degrees C per decade) Significance
1860-1880 21 0.163 Yes
1910-1940 31 0.15 Yes”
It is generally assumed that CO2 was not a major factor before 1945. So it seems as if nature was quite capable of producing warming trends of 21 and 31 years without any human influence. What am I missing here with regards to Dr. Ben Santer’s 17 years? It seems as if 31 years is not enough. I would suggest we wait 31 years to see if we get a definite signal and not spend a penny in the meantime on things that may not be necessary.
The lack of warming for 15 years followed by cooling for the last 7 years supports the assertion that the planet resists climate forcing changes (warming or cooling forcing changes) by increasing or decreasing clouds in the tropical region.
It should be noted that the so called “deniers” quote peer reviewed published paper that support the assertion that the planet’s response to any forcing change is to resist the change (negative feedback) rather than to amplify the forcing change (positive feedback).
The extreme AGW paradigm promoted by the IPCC requires that the planet amplify the CO2 warming forcing. Whether the planet’s response is to resist or amplify the CO2 greenhouse warming is the key fundamental issue.
No one disputes increases in atmospheric CO2 cause some warming.
It is curious that those promoting the extreme AGW do not discuss or acknowledge is a key fundamental scientific issue.
Seventeen years is just used to delay the obvious that many of us have known for ages. The goal post keeps changing because a number of alarmists won’t admit defeat, when it is staring them in the face. It is now 17 years because this is the longest period that the scare came about from. The world has only warmed for 17 years over the last 77 years and this cherry picked period is used to predict CAGW alarmist nonsense. When the minimum to determine a climate signal becomes longer than 17 years, no period with a greater length has any credibility because it becomes longer than the scare in the first place. Remember folks the scare first started in the 1980’s after a period of less than a decade of global warming.
Natural variation has currently dwarfed the climate changing CO2 signal. We have seen it before and we are seeing it now. The only problem with this theoretical approach, i.e.. we have had pauses in global warming before, does not address the unprecedented rise in CO2 we humans are causing, especially over the last 10 years. The Earth’s reported fever could be related to just bad surface temperature data; or, that the connection between CO2 and temperature via the trace gas radiative transfer model is…ah…imperfect. Or, and this is my thinking, that what is observed in the wet bench physics lab of CO2 and temperature is irrelevant to global atmosphere and its modulation between air and oceans. Maybe CO2 and temperature just aren’t important; other phenomena play a far larger role. Capricious connected oscillators may rule the day/night/seasons we observe.
17 years….The goldilocks number.
“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.”
This is simply backward. Natural fluctuations are not noise, it is what it is. The man made signal, if any is the damn noise here. That is why it is so difficult to find. The operative is “if any”.
Gates’ post @12:53 pm is just Gates being Santer’s water boy. And of course, Santer is full of crap. Sixteen years, nine months is too short a time frame, but 17 years is OK?
Ri-i-i-i-i-ght.
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. Either “It” is not powerful enough to counteract natural variation, or there are other natural factors now operating that were either ignored or were or are unknown or there are so many unkowns, including “it” that we cannot model climate. Your analogy is amusing but simplistic. Reality is complex and inconveniently unknowable. 2 more years of looking for “it” won’t help IMHO. 2 more years of payroll for Ben, Michael, Phil and Kev however is not amusing.