Cooler heads at NOAA coming around to natural variability

Guest Post by Steven Goddard

http://test.crh.noaa.gov/images/eax/safety/winter/NOAA-ice.jpg

It appears that global cooling recognition may be starting to make headway in the scientific community. We have this Discovery/MSNBC article about a NOAA scientist titled “Warming might be on hold, study finds

“It is possible that a fraction of the most recent rapid warming since the 1970’s was due to a free variation in climate,” Isaac Held of the National Oceanic and Atmospheric Administration in Princeton, New Jersey wrote in an email to Discovery News. “Suggesting that the warming might possibly slow down or even stagnate for a few years before rapid warming commences again.”

And Swanson thinks the trend could continue for up to 30 years.

Here’s the complete story from The Discovery Channel via MSNBC:

For those who have endured this winter’s frigid temperatures and today’s heavy snowstorm in the Northeast, the concept of global warming may seem, well, almost wishful.But climate is known to be variable – a cold winter, or a few strung together doesn’t mean the planet is cooling. Still, according to a new study, global warming may have hit a speed bump and could go into hiding for decades.

Earth’s climate continues to confound scientists. Following a 30-year trend of warming, global temperatures have flatlined since 2001 despite rising greenhouse gas concentrations, and a heat surplus that should have cranked up the planetary thermostat.

“This is nothing like anything we’ve seen since 1950,” Kyle Swanson of the University of Wisconsin-Milwaukee said. “Cooling events since then had firm causes, like eruptions or large-magnitude La Ninas. This current cooling doesn’t have one.”

Instead, Swanson and colleague Anastasios Tsonis think a series of climate processes have aligned, conspiring to chill the climate. In 1997 and 1998, the tropical Pacific Ocean warmed rapidly in what Swanson called a “super El Nino event.” It sent a shock wave through the oceans and atmosphere, jarring their circulation patterns into unison.

How does this square with temperature records from 2005-2007, by some measurements among the warmest years on record? When added up with the other four years since 2001, Swanson said the overall trend is flat, even though temperatures should have gone up by 0.2 degrees Centigrade (0.36 degrees Fahrenheit) during that time.

The discrepancy gets to the heart of one of the toughest problems in climate science – identifying the difference between natural variability (like the occasional March snow storm) from human-induced change.

But just what’s causing the cooling is a mystery. Sinking water currents in the north Atlantic Ocean could be sucking heat down into the depths. Or an overabundance of tropical clouds may be reflecting more of the sun’s energy than usual back out into space.

It is possible that a fraction of the most recent rapid warming since the 1970’s was due to a free variation in climate,” Isaac Held of the National Oceanic and Atmospheric Administration in Princeton, New Jersey wrote in an email to Discovery News. “Suggesting that the warming might possibly slow down or even stagnate for a few years before rapid warming commences again.”

Swanson thinks the trend could continue for up to 30 years. But he warned that it’s just a hiccup, and that humans’ penchant for spewing greenhouse gases will certainly come back to haunt us.

“When the climate kicks back out of this state, we’ll have explosive warming,” Swanson said. “Thirty years of greenhouse gas radiative forcing will still be there and then bang, the warming will return and be very aggressive.”

© 2009 Discovery Channel

That is strange.  We hear from highly respected authorities that we were in a period of “unprecedented warming.”  How can it be both warming and cooling at the same time?  Maybe those DC protesters didn’t need to stand out in the cold and try to shut down their primary source of energy today.

Fig A2

http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.lrg.gif

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CodeTech

May I suggest that this current cooling is caused by…
MANMADE CO2 !!!
And… in order to stop this horrible new ice age… we must stop emitting this horrible gas!
Yeah, okay, sorry, but I really get a laugh out of people who think they have it all nailed down, then are confounded when their certainty is shattered.

Phil

And the cause: “This current cooling doesn’t have one.”
I see that they still do not get out much. Maybe we should all club together to send them on a beach holiday so they can lie on their backs and look at the SUN.

Bill Ryan

…and here I thought that Mankind’s spewing of greenhouse gases was overwhelming a delicate natural climatic balance. Silly me!

What utter morons.
In fact, that is being disrespectful towards morons.
“Hey, guys, like, it’s not going to be warming, and maybe even cooling, for the next, um, 30 years (when I’m safely retired!), but this warming is coming back with a vengeance! Oh, yes! We need to immediately throw money, um, um, I mean FUND further research into this cooling aberation, because in 30 years time, it’s baaaack!”
The screams of anguish being heard around the world from the carpet-baggers and free-loaders of the AGW industry are extraordinary. Maybe they can see what happened to the Y2K industry, the Mad Cow Disease industry, and all the other fanciful public insanities over the last few years.
These people deserve to be on the unemployment scrap-heap for the rest of their tawdry lives……

Pierre Gosselin

Looks to me as if they are seeing the writing on the wall, and they are now putting in place a back door to bolt through.
No matter – it’s too late. The socialisation of America has irreversibly begun. Good luck in your new state-run country!

Lindsay H

“It is possible that a fraction of the most recent rapid warming since the 1970’s was due to a free variation in climate,”
A very PC statement !
Is there any way of quantifying scientifically this fraction ? because this is at the core of the debate
The AGW crowd will want to “proove” that its 99% agw 1% natural variation
As a sceptic I accept that human activity will have an effect that reflects the absorption bands of increased co2 and other gasses, I also accept that there is compelling evidence that a pattern of natural variations have always affected climate as distinct from weather.
A large dose of Carl Popper and the scientific method should help iin defining the fraction .

‘a cold winter, or a few strung together doesn’t mean the planet is cooling.’
Surely the converse is true also.

“It is possible that a fraction of the most recent rapid warming since the 1970’s was due to a free variation in climate,”

…and thus the tiny pea of scientific rationality began to roll down the snowy slopes of Mount Climate Disaster.

Katherine

That read to me to mean, “We’re right, even when it looks like we’re wrong. This cooling is just masking the warming.” Even if the cooling lasts 30 years (matching the 30 years of warming), it’s “just a hiccup.”
On one hand, Swanson says they don’t know what’s causing the cooling.

“This is nothing like anything we’ve seen since 1950,” Kyle Swanson of the University of Wisconsin-Milwaukee said. “Cooling events since then had firm causes, like eruptions or large-magnitude La Ninas. This current cooling doesn’t have one.”

Yet on the other hand, Swanson is confident enough to predict what will happen when it goes away.

“When the climate kicks back out of this state, we’ll have explosive warming,” Swanson said. “Thirty years of greenhouse gas radiative forcing will still be there and then bang, the warming will return and be very aggressive.”

If this cooling lasts 30 years, I think people would welcome aggressive warming.

softestpawn

Seems a good way to maintain the scare while the evidence you were using goes to pot. And by putting the scare off by 30 years they’ve still got a safe career no matter what happens to the climate in the meantime.

Jørgen F.

Danish scientists have come to similar conclusions in recent days.
Yesterday the Danish Meteorological Institute published an article on their website: “The climate hockey stick is broken”.
(In Danish: http://www.dmi.dk/dmi/klimaets_hockeystav_er_braekket )
They describe findings from a recent published study:
http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F2008JCLI2301.1&ct=1&SESSID=fdb456bdab0ff3c077e4bd9594115b2e
The major finding in this study is that the natural variability in the global temperatures the last 600 years must have been greater than Michael Mann’s prior estimations.

Mijaga

I’m not sure if they are actually coming around. It seems to me that the proponents of AGW are just trying to make excuses for why reality doesn’t match the models. They haven’t really changed their story, but merely trying to state that the current cooling can not be used to dismiss AGW. Someone is trying to have their cake and eat it too!

Aron

“Thirty years of greenhouse gas radiative forcing will still be there and then bang, the warming will return and be very aggressive.”
Makes no sense. From 15,000 years ago until present the levels of atmospheric CO2 have doubled steadily over time and then rapidly. If we were going to see aggressive and catastrophic warming from greenhouse gas forcing why in 30 years and not now? Or even before present? Who knows exactly how much greenhouse gases there needs to be for aggressive forcing to occur?
And why during the last 8000 years have temperatures declined overall despite a doubling of CO2? Why has atmospheric albedo also declined with increased CO2 when theoretically the opposite should occur?
Think about the time when the pharaohs ruled Ancient Egypt and temperatures were warmer than today. It used to be more humid in those days. Egyptian literature and murals tell us they lived on a fertile land composed of black mud and that they had to travel out to the desert. Today cooler temperatures have lowered albedo and the desert has swallowed Giza and Cairo.
They used to have proper seasonal rains too, the Sphinx itself shows us erosion from rainfall.
Around the same time, Greenland had tribes living in the north and grapes grew in in the most northern parts of North America exactly where it is freezing cold today. When the Norsemen arrived over two thousand years later they called the area Vinland precisely because of the grapes they found growing made for good wine.
We see the same thing in Britain, where a thousand years ago there was a good climate for growing grapes all over the country. Nowadays it is too cool in the north to grow decent grapes for wine.
So Swanson needs to explain why we live in a dryer cooler climate now and what is the basis for believing “bang, the warming will return and be very aggressive” beyond purely guessing?

CPT. Charles

But just what’s causing the cooling is a mystery…
Yeah, I suppose it’s hard to see things clearly when your head is tightly inserted up your favorite computer model.

Ozzie John

Interesting comment to close on….
Thirty years of greenhouse gas radiative forcing will still be there and then bang, the warming will return and be very aggressive.”
Such a strong comment with no supporting argument. Sounds like guess work is the order of the day once again !

Mike McMillan

“Suggesting that the warming might possibly slow down or even stagnate for a few years before rapid warming commences again.”
Yes, assuming the interglacial continues. Otherwise, it might be in the realm of 90,000 years.

It is quite clear that current climate models don’t incorporate any natural cycle between 1 and 100 years. This is proven by the ocean heat content trends, compared to two major models, see Fig. S1 of Barnet e.a.:
http://www.sciencemag.org/cgi/data/1112418/DC1/1
That insolation/clouds are involved also can be seen in the ocean heat content increase over the past 50 years, as the mayor heat content increase is in the subtropics, where the largest change in (low) cloud cover was measured, while increased GHGs should give a more evenly distributed warming see Fig. 2 in Levitus e.a.:
ftp://ftp.nodc.noaa.gov/pub/data.nodc/woa/PUBLICATIONS/grlheat05.pdf
Baseline conclusion: as models used the last decades of the past century to attribute most warming to the increase of GHGs, and the current trend is flat, one can say that the warming was about 50% natural, 50% GHG induced (the current natural cooling is as strong as the supposed GHG warming). Thus current models with 3°C/2xCO2 are a factor 2 too high, and the real increase is 1.5°C/2xCO2 (or less)…

Les Francis

From the text :

Earth’s climate continues to confound scientists.

What? No concensus?

In 1997 and 1998, the tropical Pacific Ocean warmed rapidly in what Swanson called a “super El Nino event.” It sent a shock wave through the oceans and atmosphere, jarring their circulation patterns into unison.

Ahhhh… Any excuse is a good one.

But climate is known to be variable – a cold winter, or a few strung together doesn’t mean the planet is cooling. Still, according to a new study, global warming may have hit a speed bump and could go into hiding for decades.

Never heard of cycles?

jmrSudbury

Wow. The Discovery Channel still fell back on the tired old meme that “[s]inking water currents in the north Atlantic Ocean could be sucking heat down into the depths” even though salinity is a minor effect as compared to cold water sinking. Warm water does not sink. We should be thankful that they are making baby steps toward the dark side of analysing real data.
John M Reynolds

jmrSudbury

Lindsay H (00:39:27), that fraction could even be 22/88 human to natural influence seeing as how 0.08C of the 0.37C 1930-1990 warming was unexplained. Those numbers are based on HadCRUT data for a full set of oceanic cycles. — John M Reynolds

Manfred

Lindsay H (00:39:27) :
“Is there any way of quantifying scientifically this fraction ?”
If this fraction is able to neutrallize the effect of the much more CO2 in the coming up to 30 years, it’s percentage should be close to 100%.
Including these natural effects into the models would require CO2 feedbacks to be negative to match models to historical temperature data.

D. King

“When the climate kicks back out of this state,
we’ll have explosive warming,” Swanson said.
explosive warming?
How are they going to get any media attention,
if they continually understate the problem?

EW

Thirty years of greenhouse gas radiative forcing will still be there and then bang, the warming will return and be very aggressive.”
This concept of shelved radiative forcing its something I can’t understand. OK, factor A is cooling our planet. Radiative forcing from CO2 counters the factor A, making the cooling flatter. It can’t be put into storage. Of course, absent factor A (after the suggested 30 years), higher CO2 might cause more forcing, but surely not as to unleash all these watts per m square accumulated during 30 years? Or am I missing something?

B Kerr

I like it, I like it.
“Instead, Swanson and colleague Anastasios Tsonis think a series of climate processes have aligned, conspiring to chill the climate.”
Yes conspiring to chill.
I take it that in the past 30 years there was been no climate alignment conspiring to cause warming?
Guess not.
What really gets me is that this will be reported as fact – NOAA Scientists say – and that since these people are experts they are beyond reproach.

Ceolfrith

This all called an old favourite to mind
“It was a press conference.
‘I’m afraid I can’t comment on the name Rain God at this present time, and we are calling him an example of a Spontaneous Para-Causal Meteorological Phenomenon.’
‘Can you tell us what that means?’
‘I’m not altogether sure. Let’s be straight here. If we find something we can’t understand we like to call it something you can’t understand, or indeed pronounce. I mean if we just let you go around calling him a Rain God, then that suggests that you know something we don’t, and I’m afraid we couldn’t have that.
‘No, first we have to call it something which says it’s ours, not yours, then we set about finding some way of proving it’s not what you said it is, but something we say it is.
‘And if it turns out that you’re right, you’ll still be wrong, because we will simply call him a … er, “Supernormal … ” – not paranormal or supernatural because you think you know what those mean now, no, a “Supernormal Incremental Precipitation Inducer”. We’ll probably want to shove a “Quasi” in there somewhere to protect ourselves” – (Douglas Adams – “So Long And Thanks For All The Fish”)

Re: Jørgen F.

Danish scientists have come to similar conclusions in recent days.
Yesterday the Danish Meteorological Institute published an article on their website: “The climate hockey stick is broken”.

Jørgen, could you or somebody please translate the article for us?

Sella Turcica
Phillip Bratby

“This is nothing like anything we’ve seen since 1950”. The trouble is these people seem to have no idea that climate change used to happen in the past. What is 50 years compared to the length of the Holocene or since the start of the current ice-age? I wonder if they believe in the hockey stick and so the Little Ice Age does not figure in their thinking.

Pat

Absoluet classic!!!
“This all called an old favourite to mind
“It was a press conference.
‘I’m afraid I can’t comment on the name Rain God at this present time, and we are calling him an example of a Spontaneous Para-Causal Meteorological Phenomenon.’
‘Can you tell us what that means?’
‘I’m not altogether sure. Let’s be straight here. If we find something we can’t understand we like to call it something you can’t understand, or indeed pronounce. I mean if we just let you go around calling him a Rain God, then that suggests that you know something we don’t, and I’m afraid we couldn’t have that.
‘No, first we have to call it something which says it’s ours, not yours, then we set about finding some way of proving it’s not what you said it is, but something we say it is.
‘And if it turns out that you’re right, you’ll still be wrong, because we will simply call him a … er, “Supernormal … ” – not paranormal or supernatural because you think you know what those mean now, no, a “Supernormal Incremental Precipitation Inducer”. We’ll probably want to shove a “Quasi” in there somewhere to protect ourselves” – (Douglas Adams – “So Long And Thanks For All The Fish”)”
What is the answer to the ultimate question? 42. (And the question was wrong).

The NOAA know whats coming…they know the Sun is whimpering just before a solar grand minimum, but dont want to say it.
BTW…for those interested, Landscheidt Cycles Research is back on line with a fresh look and new server (same as Climate Audit) and I have some new graphs using the original Solanki 14C data, the evidence continues to build.
http://landscheidt.auditblogs.com/

Jack Simmons

From Wikipedia:
Ad hoc hypothesis
In science and philosophy, ad hoc means the addition of extraneous hypotheses to a theory in order to save it from being falsified. Ad hoc hypotheses compensate for anomalies not anticipated by the theory in its unmodified form. Scientists are often skeptical of theories that rely on frequent, unsupported adjustments to sustain them. Ad hoc hypotheses are often characteristic of pseudoscientific subjects.[1] Much of scientific understanding relies on the modification of existing hypotheses or theories but these modifications are distinguished from ad hoc hypotheses in that the anomalies being explained propose a new means of being real.
Ad hoc hypotheses are not necessarily incorrect, however. An interesting example of an apparently supported ad hoc hypothesis was Albert Einstein’s addition of the cosmological constant to general relativity in order to allow a static universe. Although he later referred to it as his “greatest blunder”, it has been found to correspond quite well to the theories of dark energy.[2]

3x2

Manfred (02:18:33) : feedbacks to be negative
Feedbacks! Negative! Here at Second Life Science have proved beyond a doubt that such mechanisms are purest fantasy. As you should know by now – For every action there is a self re-enforcing free fall into chaos.
(from the text) “Earth’s climate continues to confound scientists.”
So perhaps the science is not as “settled” as some would have us believe. An admission that there may well be more to climate than just good old CO2 and positive feedbacks? Who knew?

Jim H

I’ve said it before and I’ll say it again – we only have to wait. When in 10 years time the earth is noticeably cooler than today, when food prices have rocketed, and food shortages start occuring, the public will turn on the AGW brigade. The disconnect between what people can see happening in their lives and the AGW rhetoric will be so great that the AGWers will become the objects of firstly mirth and derision, then as food shortages increase, anger, and even violence.

Speaking of the Sun….did anyone get hold of a copy of that paper from Nir Shaviv supposedly showing a strong link in solar forcing using ocean heatsinks. Was it rubbish or dont we know yet?

Ron de Haan

This is nothing more but a little crack in the AGW doctrine.
As long as NOAA is producing bias data, nothing has changed.
What we need is honest, clean data projections and an official statement from all relative institutions to the Governments as well as a public statement in a world wide broadcast dismissing the AGW/CO2 doctrine.
This statement must be very clear in dismissing the role of CO2 and the CO2 mitigation plans of the World’s Governments and it must involve the United Nations, the IPCC and the World Meteorological Organization.
The statement must also contain a clear declaration about our future sea levels and it must also make clear that burning of fossil fuels has no negative effect on or climate in terms of CO2.
In other words, we need an official statement, strong and clear enough to put a hold on all CO2 mitigation legislation, cap & Trade, tax plans as well as coastal defense projects which are based on the incorrect IPCC future sea level projections.
Without such a public declaration, I am afraid the political machinery is to far on track to be halted and nothing will change.

John Judge

This reminds me of that classic military press release, “Our forces have conducted a series of brilliant retreats while the enemy continues to advance in total confusion”.

Aron
B Kerr

Since we are also discussing the Discovery Channel and its scientific input; were in the UK we are being treated to “Ways to Save the Planet”.
This week we had “Space Sunshield”.
Doctor Roger Angle, yes that was his name, wants to place lenses into space and these lenses will reflect/refract the suns rays. The lenses will be placed in a special point in space, a bit mysterious, where the sun and earth’s gravity will cancel one another out. (I think they meant a Lagrange point. But then again, I was not sure if they knew that there was more than one L-point. )
To get these mirrors into space they need a rocket.
The program had a Physicist, an expert, who explained that the lenses would be fired into space using a “coil gun”. As luck would have it one of Dr. Angle’s neighbours has a coil gun. Guess you guys in the States all have coil guns.
I’ll not spoil it for you but the boys from the Myth Busters will be proud and more scientific.
Now the discovery team turn to conventional rockets to get the lenses into space. The “Rocketters” construct a rocket which can be fired at the Otterburn range here in the UK. Excitement mounts as we get closer to the the moment of launch. At which point the Discovery chap sees a manual which outline thirteen hundred ways why the launch will fail. Yes 1300 ways to fail. He is not a happy chappy!! Livid!!
You guessed it, the launch failed and all video images were lost.
Hang on a moment, they find a memory card, it will contain images.
No it didn’t.
The programme now finishes on an up beat theme.
Everything is a success, but you knew that, and Doctor Angle is happy, mind you it was hard to tell. We now have the technology and nothing can stop the 16 TRILLION lenses going into space and saving the planet.
So to the future.
The way ahead is clear all we need do is to launch Saturn 5/Apollo 11 style rockets into space at the rate of one every 20 minutes for the next six and a half years.
The cost of doing nothing would be worse!
If you want a laugh check out.
http://www.discoverychannel.co.uk/web/ways-to-save-the-planet/
I really enjoyed this, I really did, it cheered me up no end.
Still think Bugs Bunny is more believable in “Hare way to the Stars”.

dearieme

Let’s have no pretence that this AGW stuff is honest error. It may have started off as inept science by fifth-rate physicists, but they eventually defended their position, and their interests, by dishonesty.

Charlie

The global cooling we are experiencing is caused by a lack of sun spot activity…

Roger H

Uh Oh! I can already see a new proclamation coming after King Obama and Prince Al get the Carbon Tax in place. Within a few months they will simply declare, without debate, that the new plan has already reversed the warming of our planet and this proves that their taxation of everyone and everything for any and all reasons is a good thing.

Idle thoughts of an idle fellow. I have recently become aware of Sudden Stratospheric Warming (SSW). Let me hypothesise. At current levels of extent and frequency, SSW has a small radiative forcing, but when SSW occurs, (unlike El Nino/La Nina) it always results in cooling the world. Suppose in the past, say during the Maunder minumum, SSW was far more extensive, and far more frequent. SSW could then be the cause of a cold earth. What happened at the end of the 20th century could be an unusually quiet SSW, resulting in a warming earth. Should SSW pick up, the earth could cool. All very hypothetical. There is some connection between SSW and cosmic rays; what the connection is I am dont know. However, SSW is a KNOWN effect. The IPCC has not caluclated the radiative forcing of SSW, and cannot possibly know it’s history; it was only observed in 1952, and accurate data has only been available from satellites. So the IPCC is just plain worng when it claims that the rise in world temperatures at the end of the 20th century cannot be explained by KNOWN facors, other than CO2 and AGW. SSW can explain it; albeit in a very hypothetical way.

Jørgen F.

John A (02:55:16) :
Translation From http://www.dmi.dk/dmi/klimaets_hockeystav_er_braekket )
The climate hockey stick is broken.
It has been shown & used in many connections, and it has been the icon of how ‘wrong’ the climate has developed since the industrialization. We talk about the Mann curve or the hockey stick curve that shows the development of surface temperatures on the NH throughout the last 600 years. New Danish research breaks the foundation of the Mann curve.
“The hockey stick curve is not right” says climate scientist Bo Christensen from the Danish Climate Centre and adds: “This does not mean the we cancel manmade global warming, but the foundation has been more nuanced”.
It created attention when Michael Mann and several others in 1998 published a curve over the NH temperature development the last 600 years. The curve shows stabile and nearly constant temperatures the first 500 years and an abrupt increase after year 1900. It can be interpreted as the natural variations are small compared to AGW. An emotional debate followed (inside & outside of science) – a debate that is still ongoing.
Scientist at DMI now shows that the mathematical methods used to reconstruct climate has serious limitations.
“Popular speaking you can say that the hockey stick is flat. Earlier reconstructions has underestimated the strength of natural climate variation” says Bo Christiansen and adds: “in addition the methods has a great element of ‘chance’
Graph text “the black curve shows the NH mean temperature in a climate model. The coloured curves show the results of different reconstruction methods. The methods are ‘trained on the last 100 years of data and in this period they fit the climate model. In the period 1500-1900 the reconstruction deviates much from the model – and from each other. Especially the reconstructions underestimate the strength of natural climate variations. The thick curves are fitted.
“The Mann graph is not directly based on measurement of temperatures. We have only had those from around 1850” Co- writer on the new research paper explains. ”You recreate through statistical methods from ‘proxy’ climate indicators, as year rings fund in trees, corals, ice cores and historical papers.” He explains.
It is those statistical methods the Danish scientist has investigated. By winding the climate models, normally used the predict future climate, backwards, they have tested different reconstructions methods. And the all have the same weaknesses. ”We have discovered a huge problem, that limits the value of reconstruction studie” says Bo Chistiansen.
“Climate models are so good that they can be used to tests earlier methods used to reconstruct the climate. The climate model shows us a world that looks realistic with the same types of ‘spacious’ variations. The advantage of the climate model is that we know it’s climate variations not only within the last 100 years – but also longer back in time.
The DMI scientist results have been published in Journal of Climate.

Jari

Here is the abstract of the Danish paper:
A surrogate ensemble study of climate reconstruction methods: Stochasticity and robustness.
Bo Christiansen, T. Schmith, P. Thejll
Danish Meteorological Institute, Copenhagen, Denmark
Bo Christiansen
T. Schmith
P. Thejll
Reconstruction of the Earth’s surface temperature from proxy data is an important task because of the need to compare recent changes with past variability. However, the statistical properties and robustness of climate reconstruction methods are not well known, which has led to a heated discussion about the quality of published reconstructions. In this paper we present a systematic study of the properties of reconstruction methods. The methods include both direct hemispheric-mean reconstructions and field reconstructions including reconstructions based on canonical regression and regularized expectation maximization algorithms. The study will be based on temperature fields where the target of the reconstructions is known. We are in particular interested in how well the reconstructions reproduce low-frequency variability, biases, and trends.
We use a climate simulation from an Ocean-Atmosphere General Circulation Model of the period AD 1500–1999 including both natural and anthropogenic forcings. However, reconstructions include a large element of stochasticity and to draw robust statistical interferences we need reconstructions of a large ensemble of realistic temperature fields. To this end we have developed a novel technique to generate surrogate fields with the same temporal and spatial characteristics as the original surface temperature field from the circulation model. Pseudo-proxies are generated by degrading a number of grid-box time-series. The number of pseudo-proxies and the relation between the pseudo-proxies and the underlying temperature field are determined realistically from Mann et al. (1998).
We find that all reconstruction methods contain a large element of stochasticity and it is not possible to compare the methods and draw conclusions from a single or a few realizations. This means that very different results can be obtained using the same reconstruction method on different surrogate fields. This might explain some of the recently published divergent results.
We also find that the amplitude of the low-frequency variability in general is underestimated. All methods systematically give large biases and underestimate both trends and the amplitude of the low-frequency variability. The underestimation is typically 20–50 %. The shape of the low-frequency variability, however, is in general well reconstructed.
We find some potential in validating the methods on independent data. However, to gain information about the reconstructions ability to capture the “pre-industrial” level it is necessary to consider the average level in the validation period and not the year-to-year correlations. We also report on the influence on the reconstructions of the number of proxies, the type of noise used to generate the proxies, the strength of the variability, as well as the effect of detrending the data prior to the calibration.

schnurrp

Could it be air pollution from a rapidly industrializing China and India? This may explain a similar “pause in warming” during 1940-1975 after which the industrialized nations cleaned up their act with increased solar radiation resulting.
Here.

David Archibald

This is reminiscent of Keenlyside, is it not? He said that AGW would be on hold for 15 years. Now it is permissible for the faithful to believe that it will be on hold for 30 years. Do I hear an advance on that? AGW is a broad church with many saints that individual believers can follow.
Jim Hansen’s problem is that he has to continue to ratchet up his rhetoric. It started with Usufruct and the Gorilla, at AGU in 2007 he said that the danger level for CO2 is 350 ppm (now 450 ppm?), then it was death trains and the Holocaust, and now exhortations to civil disobedience. How is he going to up it from here? Self immolation as a protest against his own CO2 emissions over the rest of his life? Self immolation as a protest against Al Gore’s CO2 emissions over the rest of Al Gore’s life? Any suggestions? The man is going to be struggling from here.
Meanwhile, the Oulu neutron count continues to climb and the F 10.7 radio flux falls as the Earth moves away from the Sun (my mistake on a previous post). I still believe that in the absence of good sunspot data that the month of minimum will be put in the middle of the F 10.7 quiet period, no matter what happens to cycle 23 sunspots.
And for a more immediate, real world impact, what is going to happen to the North American Spring planting season? Any ideas?

TS

The picture seems to be quite clear. Sun dominates temperatures via oceans’ heat capacity. Thus eg. El Nino and La Nina reflect Sun’s activity from longer period.
In 1990’s there first was long-lasting El Nino and finally super El Nino in 1998, which was caused of 20 years extremely high activity period of Sun. These boosted temperatures to a new level (because feedback processes, ENSO affects to temperatures for longer period than only that when sea temperature anomalies exist).
During 2000’s the effect of super El Nino have been vanishing and thus temperatures have curved to slowly decrease. Last year’s moderate La Nina accelerated this trend and this year’s La Nina will continue to do so also. Recent solar activity suggests that La Ninas will be dominant in near future. Maybe in 10 yrs we are back to 70’s temperatures or even lower.

Allan M R MacRae

schnurrp (04:26:04) :
Could it be air pollution from a rapidly industrializing China and India? This may explain a similar “pause in warming” during 1940-1975 after which the industrialized nations cleaned up their act with increased solar radiation resulting.
Answer:
Probably no. Please see Douglas Hoyt’s post below. He is the same D.V. Hoyt who authored/co-authored the four papers referenced below.
http://www.climateaudit.org/?p=755
Douglas Hoyt:
July 22nd, 2006 at 5:37 am
Measurements of aerosols did not begin in the 1970s. There were measurements before then, but not so well organized. However, there were a number of pyrheliometric measurements made and it is possible to extract aerosol information from them by the method described in:
Hoyt, D. V., 1979. The apparent atmospheric transmission using the pyrheliometric ratioing techniques. Appl. Optics, 18, 2530-2531.
The pyrheliometric ratioing technique is very insensitive to any changes in calibration of the instruments and very sensitive to aerosol changes.
Here are three papers using the technique:
Hoyt, D. V. and C. Frohlich, 1983. Atmospheric transmission at Davos, Switzerland, 1909-1979. Climatic Change, 5, 61-72.
Hoyt, D. V., C. P. Turner, and R. D. Evans, 1980. Trends in atmospheric transmission at three locations in the United States from 1940 to 1977. Mon. Wea. Rev., 108, 1430-1439.
Hoyt, D. V., 1979. Pyrheliometric and circumsolar sky radiation measurements by the Smithsonian Astrophysical Observatory from 1923 to 1954. Tellus, 31, 217-229.
In none of these studies were any long-term trends found in aerosols, although volcanic events show up quite clearly. There are other studies from Belgium, Ireland, and Hawaii that reach the same conclusions. It is significant that Davos shows no trend whereas the IPCC models show it in the area where the greatest changes in aerosols were occurring.
There are earlier aerosol studies by Hand and in other in Monthly Weather Review going back to the 1880s and these studies also show no trends.
So when MacRae (#321) says: “I suspect that both the climate computer models and the input assumptions are not only inadequate, but in some cases key data is completely fabricated – for example, the alleged aerosol data that forces models to show cooling from ~1940 to ~1975. Isn’t it true that there was little or no quality aerosol data collected during 1940-1975, and the modelers simply invented data to force their models to history-match; then they claimed that their models actually reproduced past climate change quite well; and then they claimed they could therefore understand climate systems well enough to confidently predict future catastrophic warming?”, he close to the truth.

MarkW

Let’s see if I have this right.
A tiny fraction of the warming of the last 30 years was due to natural variability.
On the other hand, when natural variability swings to the cold side, it is powerfull enough to cancel out warming completely, and then some, for thirty years.
It seems to me that if the cold side is enough to cancel out warming, then the warm side had to have been at least 50% of the warming that was observed.

Allen63

According to the Discovery article, a potential next 30 years of cooling does not mean its cooling. So, just maybe, the 30 years of warming prior to 2000 does not mean its warming.
Yes. Using the 30 year rule (i.e. less than 30 years of data is meaningless as regards to AGW) does allow most pro-AGW Climate researchers to comfortably finish their career without changing their possibly erroneous opinions (opinions — as they have no concrete proof of their hypothesis).