Guest post by Dr. Don J. Easterbrook
1934 has long been considered the warmest year of the past century. A decade ago, the closest challenger appeared to be 1998, a super-el nino year, but it trailed 1934 by 0.54°C (0.97°F). Since then, NASA GISS has “adjusted” the U.S. data for 1934 downward and 1998 upward (see December 25, 2010 post by Ira Glickstein) in an attempt to make 1998 warmer than 1934 and seemingly erased the original rather large lead of 1934 over 1998. The last phases of the strong 2009-2010 el nino in early 2010 made this year another possible contender for the warmest year of the century. However, December 2010 has been one of the coldest Decembers in a century in many parts of the world, so 2010 probably won’t be warmer than 1998. But does it really matter? Regardless of which year wins the temperature adjustment battle, how significant will that be? To answer that question, we need to look at a much longer time frame‒centuries and millennia.
One of the best ways to look at long-term temperatures is with isotope data from the GISP2 Greenland ice core, from which temperatures for thousands of years can be determined. The ice core isotope data were obtained by Minze Stuiver and Peter Grootes from nuclear accelerator measurements of thousands of oxygen isotope ratios (16O/18O), which are a measure of paleo-temperatures at the time snow fell that was later converted to glacial ice. The age of such temperatures can be accurately measured from annual layers of accumulation of rock debris marking each summer’s melting of ice and concentration of rock debris on the glacier.
The past century
Two episodes of global warming and two episodes of global cooling occurred during the past century:
1880 to 1915 cool period. Atmospheric temperature measurements, glacier fluctuations, and oxygen isotope data from Greenland ice cores all record a cool period from about 1880 to about 1915. Many cold temperature records in North America were set during this period. Glaciers advanced, some nearly to terminal positions reached during the Little Ice Age about 400 years ago. During this period, global temperatures were about 0.9 ° C (1.6 ° F) cooler than at present. From 1880 to 1890, temperatures dropped 0.35 ° C (0.6° F) in only 10 years. The 1880 –1915 cool period shows up well in the oxygen isotope curve of the Greenland Ice Sheet.
1915 to 1945 warm period. Global temperatures rose steadily in the 1920s, 1930s, and early 1940s. By the mid-1940s, global temperatures were about 0.5 °C (0.9° F) warmer than they had been at the turn of the century. More high temperature records for the century were recorded in the 1930s than in any other decade of the 20th century. Glaciers during this warm period retreated, temperatures in the 1930s in Greenland were warmer than at present, and rates of warming were higher (warming 4°C (7° F) in two decades). All of this occurred before CO2 emissions began to soar after 1945, so at least half of the warming of the past century cannot have been caused by manmade CO2.
1945 to 1977 cool period. Global temperatures began to cool in the mid–1940’s at the point when CO2 emissions began to soar. Global temperatures in the Northern Hemisphere dropped about 0.5° C (0.9° F) from the mid-1940s until 1977 and temperatures globally cooled about 0.2° C (0.4° F). Many of the world’s glaciers advanced during this time and recovered a good deal of the ice lost during the 1915–1945 warm period. Many examples of glacial recession cited in the news media show contrasting terminal positions beginning with the maximum extent at the end of the 1880-1915 year cool period and ending with the minimum extent of the recent 20 year warm period (1977-1998). A much better gauge of the effect of climate on glaciers would be to compare glacier terminal positions between the ends of successive cool periods or the ends of successive warm periods.
1977 to 1998 global warming The global cooling that prevailed from ~1945 to 1977 ended abruptly in 1977 when the Pacific Ocean shifted from its cool mode to its warm mode in a single year and global temperatures began to rise, initiating two decades of global warming. This sudden reversal of climate in 1977 has been called the “Great Pacific Climate Shift” because it happened so abruptly. During this warm period, alpine glaciers retreated, Arctic sea ice diminished, melting of the Greenland Ice Sheet occur.
The abruptness of the shift in Pacific sea surface temperatures and corresponding change from global cooling to global warming in 1977 is highly significant and strongly suggests a cause-and-effect relationship. The rise of atmospheric CO2, which accelerated after 1945 shows no sudden change that could account for the “Great Pacific Climate Shift”.
1999 to 2010 global cooling. No global warming has occurred above the 1998 level and temperatures have declined slightly.
The past 500 years
Temperature oscillations recorded in Greenland ice cores over the past 500 years (Fig. 2) are truly remarkable. At least 40 periods of warming and cooling have occurred since 1480 AD, all well before CO2 emissions could have been a factor.
The past 5,000 years
Figure 3 shows oxygen isotope ratios from the GISP2 Greenland ice core for the past 5,000 years. Note that temperatures were significantly warmer than present from 1500 to 5000 years ago.
The past 10,000 years
Most of the past 10,000 have been warmer than the present. Figure 4 shows temperatures from the GISP2 Greenland ice core. With the exception of a brief cool period about 8,200 years ago, the entire period from 1,500 to 10,500 years ago was significantly warmer than present.
Another graph of temperatures from the Greenland ice core for the past 10,000 years is shown in Figure 5. It shows essentially the same temperatures as Cuffy and Clow (1997) but with somewhat greater detail. What both of these temperature curves show is that virtually all of the past 10,000 years has been warmer than the present.
So where do the 1934/1998/2010 warm years rank in the long-term list of warm years? Of the past 10,500 years, 9,100 were warmer than 1934/1998/2010. Thus, regardless of which year ( 1934, 1998, or 2010) turns out to be the warmest of the past century, that year will rank number 9,099 in the long-term list.
The climate has been warming slowly since the Little Ice Age (Fig. 5), but it has quite a ways to go yet before reaching the temperature levels that persisted for nearly all of the past 10,500 years.
It’s really much to do about nothing.
From Peru.
A correction to what you did with your ending point:
Starting at 1998 at the peak of an El Nino and ending with the first 1/2 of 2010 doesn’t give an accurate picture as to whether there has been a warming, flat, or cooling trend since 1998. The La Nina that followed the 1998 El Nino ran its course. But the La Nina that is following the 2009/10 El Nino hasn’t run its course yet. So to pick an ending point before it does is imbalanced since the trough of the 1999 La Nina is in it but the completed trough of the 2010/11 La Nina is not. It is easy to predict that when the current La Nina finishes there will be a cooling tend in the data since 1998.
From Peru,
Watch these two videos and tell me if GISS is 100% trustworthy:
Does GISTemp change?
part 1
Manfred: Have you read this 2009 paper titled “If It’s That Warm, How Come It’s So Damned Cold”? authored by James Hansen, et al?
http://www.columbia.edu/~jeh1/mailings/2010/20100115_Temperature2009.pdf
It seems to fit today’s theme.
Does GISTemp change?
part 2
Manfred says:
December 29, 2010 at 8:07 pm
“Actually, it was your proposal to skip 1998.
You try to compare 1998 and 2010 by skipping 1998 completely, and start in 1999 right in the middle of the deepest La Nina dominated temperatures of the decade. On the other side, however, you prefer ending in 2010, mostly dominated by another El Nino.
That’s a bit unsporty.”
I did not mentioned at all 1999. I started from 1979, the year that began the satellite record. I ended in 2010 because that is the present year.
“I left out 2010. Sorry for that. In a few months this tiny increase will be gone as well, though not in dubious GISS data, I suppose.”
This not so tiny increase will be offset by La Niña cooling, but the trend will not, as it hasn’t all those years since 1998.
Jack Greer says:
“Jones clearly said that even a 15 year timeline was sometimes too short to establish a meaningful trend… yet another prime example of non-robust cherry-picking. When is that weak tactic going to stop around here?”
It is you and your alarmist cronies who constantly cherry-pick. So let’s look at the entire Holocene, shall we? click
Nothing unusual is happening with the climate. Nothing. But continue your cognitive dissonance-induceced scare, for what it’s worth.
The rest of us know better.
From Peru says:
“How do you explain that in just a century Greenland warmed to levels seen in the Holocene Maximum?”
You just don’t understand. It is only natural climate variability, which has occurred numerous times throughout the pre-SUV past. Greenland is far from the warmer temperatures of the past. And CO2 has very little to do with any of it.
Quit trying to scare yourself and the children.
Harrywr2, I thought CO2 was also about reflecting solar energy back to the surface and radiating absorbed heat at nighttime so the convection shouldn’t be a real issue. The only reason you wouldn’t be able to measure a difference in greenhouses is because CO2 has no effects.
Ben D.
What I am urging is that people practice some consistency in the skeptical arguments.
For my own part I try to maintain a consistent approach.
1, if you don’t show your data and tour methods (code) I am not obligated to take your results seriously. skeptic or non skeptic.
2. If you argue on one thread that we cannot estimate a global temperature from 7000 stations then I fully expect you to question ANY reconstruction based on proxies from limited areas.
3. if you argue about the accuracy of thermometers I expect to see you demanding error bars on all reconstructions.
now to your points
“But as GISS shows, greenland being warm means that a good portion of the world map becomes red suddenly. I am not one to say that Greenland is either good or bad as a place to measure global temperature, but if you put any stock of faith in GISS (which I admit you do not….then this might be a starting point of some sort.)”
actually if polar amplification is accurate greenland would warm more rapidly than the rest of the world. So it would not be a good place to start unless you could accurately assess the amount of amplification. 2nd. In some recent work with greenland ice cores its been shown that they do correlate differently with different grid cells.
“Greenland’s temperature versus the rest of the world might be a better comparison with our known temperature records. I think that might be the better question here regarding assumption of Greenland being the entire world.”
I guess my point is this. We complain when Mann shows a chart of the NH reconstruction of say summer month temps. We say ” what about the other months, what about the SH, etc etc. I expect the same kind of responses when I see a chart of greenland ice cores. Measured, systematic, consistent, principled skepticism. NOT selective skepticism.
“1. What’s our best estimate of the temp over the next 100 years.
Barring any major changes in solar output etcetc, probably a warming of .7 – 1 degrees like the previous century. I put in .3 as possible for CO2 increases. Biosphere might just take care of a lot of it, I think its something to think about anyway. Regardless, this is something we could argue about, and it would be rather fruit-less as this is nothing more then “an educated guess” with some being more educated then others.”
there is nothing wrong with educated guesses. the key point would be documenting your assumptions and presenting the case.
On your other points, I’d agree that nuclear seems to be a win win. But most AGwers are so tied to a prefferred solution that they seem incapble of seizing the moment to make a big nuk push. odd.
anyway, thanks for your balanced and thoughtful comments
From Peru says:
December 29, 2010 at 5:26 pm
Very funny how Dr. Don J. Easterbrook is “hiding the incline” of Greenland temperatures.
………..Is based on the GISP2 Ice Core Temperature data. You can download it here:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/isotopes/gisp2_temp_accum_alley2000.txt
What is notorious is that the data end in … 1905!
I see on the graph in figure 5 that the bottom axis ends in 1905 (95) so what exactly is your point?
I get the impression you went on the “Skeptical Science” blog and copied verbatim the criticism without actually reading Don Easterbrook’s post, the point of which is to demonstrate large temperature swings through the last few thousand years, i.e. the current temperature rise is quite normal.
What many don’t realise is that the debate is not about whether we have had warming. No-one disputes it. The debate is whether the warming is unnatural. This post answers that argument, by examining temperature changes over the past few thousand years.
I get the impression that this post is a bit above the heads of some readers who seem to be posting inane comments that demonstrate they haven’t really understood it.
Maybe we need a “dumbed down” version that they understand.
we’re getting comments to the effect “I don’t see a dangerous hocky stick so therefore it must be rubbish”.
It would have been nice to have had an intelligent debate about temperature swings through the millenia rather than this rather mindless ranting.
I think unfortunately many posters are not really up to a scientific debate.
John Finn says:
December 29, 2010 at 9:07 am
Do you have any evidence that the decline in temperatures “deepened towards the late 1970s”? I’m sorry if the “cooling 1970s” fits with your theory but the fact remains that there was very little cooling after the mid-1950s. The 1970s were marginally – though not significantly – warmer than the 1960s. The 1955-80 trend is flat, i.e. neither warming nor cooling.
The one off records of deep lows and snow levels, cold winters etc occurred in the 70’s, the yearly global GISS record shows the 70’s as flat across the PDO negative phase of 1945-1975. But the big events happen in the winter when the low solar output, neg PDO and neg AMO were present, this was the time when science was suspecting another ice age. We are in a similar point now, the AMO is edging negative already and the solar output will be lower than SC20. Dont forget that the era I am referring to had the highest solar cycle on record which explains the small world wide recovery at 1955. Solar is important but the oceans rule.
Amino Acids in Meteorites says:
December 29, 2010 at 8:17 pm
From Peru.
A correction to what you did with your ending point:
Starting at 1998 at the peak of an El Nino and ending with the first 1/2 of 2010 doesn’t give an accurate picture as to whether there has been a warming, flat, or cooling trend since 1998. The La Nina that followed the 1998 El Nino ran its course. But the La Nina that is following the 2009/10 El Nino hasn’t run its course yet. So to pick an ending point before it does is imbalanced since the trough of the 1999 La Nina is in it but the completed trough of the 2010/11 La Nina is not. It is easy to predict that when the current La Nina finishes there will be a cooling tend in the data since 1998.
I see – so you want to use a short term trend which begins with an El Nino and ends with a La Nina. This tactic should enable you to build up a series of cooling trends throughout the last century. The fairest way is to go peak to peak or trough to trough (not peak to trough) so use 1998-2010 or 1999-2011 (or 2009) – take your pick. It doesn’t matter which both show a positive trend.
John Finn says:
December 30, 2010 at 4:05 am
I see – so you want to use a short term trend which begins with an El Nino and ends with a La Nina. This tactic
Whatever. You can manipulate data any way you’d like to come up with the results you’d wish for. My point was not about peak to peak and trough to trough. That is what you characterized it as. If you wish to say the world is warming then good luck to you.
John Finn
I see you didn’t comment on the videos I posted.
John Finn says:
December 30, 2010 at 4:05 am
take your pick
Shouldn’t you have said “take your pick from the options I have supplied, that way you’ll come up with the answer I want you to come up with” ?
oldseadog says:
December 29, 2010 at 1:50 am
The concentration doesn’t matter for how much LWIR absorption occurs. The only thing that matters is the total number of molecules. In a greenhouse with a gas column depth of perhaps 12 feet (floor to ceiling) a concentration of 2000ppm is only equivalent to a 60 foot column of normal atmosphere.
In order to simulate the CO2 LWIR absorption of just the lower 6000 feet of atmosphere inside a greenhouse would require a concentration of 200,000ppm (20%) which is toxic to animals and maybe (I’d have to look it up but I know that beneficial effect for plants stops at about 2000ppm) for plants too. Even then the greenhouse would only be warmer by about a single degree C. I don’t think you’d be able to measure the effect at 2000ppm because you couldn’t adequately control the experiment to compare 400ppm vs 2000ppm down to a hundredth of a degree difference in temperature. Any tiny difference aside from CO2 between the two setups could cause a 0.01 degree divergence.
John Tyndall discovered this 150 years ago along with the logarithmic curve in total absorption with increasing number of molecules of absorptive gases. Tyndal performed literally thousands of experiments on a score of different gases and with each gas he varied just about everything he could from the length of the column containing the gas to the partial pressure of the gas to the temperature of his thermal IR heat source. Tyndall “wrote the book” on this subject and his results, although refined in precision and accuracy since then, have withstood the test of time.
Henry@from Peru
I think you might be confused here on this site.
Here we want more warming, we like it, we take our holidays where it is warm.
and we want more carbon dioxide
because it is better for forest growth
You are welcome to check my blog as to why I think that modern warming is natural and has nothing to do with the carbon dioxide
http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok
OK?
UK Winter may be the coldest in 1000 years.
http://stevengoddard.wordpress.com/2010/12/30/winter-may-be-coldest-in-1000-years/#comment-26233
Dr. Easterbrook would never be able to publish this analysis in a peer-reviewed journal on climate change. There are several reasons for that.
He presents the GISP2 data as if it is new, and surprising, and sufficient in itself to discredit countervailing work on climate change.
He never mentions that this is 17-year-old data that has been reviewed and analyzed in tens of publications on climate change over the past 15 years, including the IPCC reports.
He doesn’t mentions the many publications that show that this northern-hermisphere, GISP2 data is contradicted by southern-hemisphere ice core data, revealing a millennial seesaw of warming and cooling between the poles (e.g. Steig, Alley, 2002).
He doesn’t mention the publications that show GISP2 data in the context of global processes and other types of climate data from around the world (e.g. Barker, 2009 or Sigman, 2010).
Instead, Easterbrook publishes this intellectually dishonest analysis, which would not pass peer review, in this public forum, where readers don’t have the background to recognize its flaws?
Why?
Bob from the UK says:
December 30, 2010 at 1:39 am
“I see on the graph in figure 5 that the bottom axis ends in 1905 (95) so what exactly is your point?”
My point is that Dr. Don J. Easterbrook used the data as if the end of the timeseries is the present (it is no clue in text about it, that text argument as if the graph end in the present. The only clue is in the small labels in the x-scales that easily are lost. This is the “small letters trick”, a common commercial trick used to deceive the consumer).
It isn’t, and if you include the last 100 years of warming you found that we are now at the levels of the Holocene Maximum warming, erasing millenia of natural cooling.
“I get the impression you went on the “Skeptical Science” blog and copied verbatim the criticism without actually reading Don Easterbrook’s post”
Nope. Skepticalscience was absolutely not used as my source, only the GISP2 ice core data , and the meteorological temperature record in Greenland
“the point of which is to demonstrate large temperature swings through the last few thousand years, i.e. the current temperature rise is quite normal”
Do you consider “normal” a 2-4ºC warming in just 100 years?
“What many don’t realise is that the debate is not about whether we have had warming. No-one disputes it”
Really? What about all the nonsense about the “post-1998 global cooling”?
“The debate is whether the warming is unnatural. This post answers that argument, by examining temperature changes over the past few thousand years.”
This post don’t answer that argument, only shows temperature variations, not the causes of warming and cooling. What is clear, once you include the last 100 years of warming (from meteorological data) is that in a century we are back, in Greenland, to the warmth of the Minoan Warming and the Holocene Maximum. That is, modern warming erased millenia of cooling.
Now, what caused this warming?
Whatever it is, it must act against the cooling caused by Milanktovich Cycles (orbital, earth inclination and precessional cycles) that are causing since 10 000 years ago a gradual cooling in the Arctic.
You can visualize Milanktovich Cycles here, along with CO2, CH4 and temperature from ice cores in the Interactive Vostok Viewer:
http://www.brightstarstemeculavalley.org/science/climate.html
Now check, what has varied so much in last 100 years?(clue, it has nothing to do with Earth inclination, precession or orbital variations)
Play with the interactive Vostok Viewer, then comment!
I continue to find it interesting at how a simple presentation of the data is so unsettling/disturbing for the pro-AGW’ers.
To continue on with that reaction, here is some more data for you.
Antarctica versus Greenland ice core proxy temperatures over the last 22,000 years – the transition out of the last ice age until today. [Please note the Older Dryas Event at 14,300 years ago so that one can get some perspective on the Younger Dryas Event which was smaller and less significant than its Older version].
http://img46.imageshack.us/img46/9509/transitioniceagegrlndan.png
And then Antarctica and Greenland over the last ice age – 120,000 years. [Please note how Greenland has much more variability – the 25 Dansgaard-Oeschger events of which the 3 Dryas Events are just examples of].
http://img841.imageshack.us/img841/9484/lasticeageglant.png
And then the North Atlantic proxy temperatures versus Antarctica and CO2 and global solar irradiance over the last 800,000 years. [Please note how small the CO2 influence is especially considering it lags behind the temperature changes by 800 to 2000 years thoughout the entire record].
http://img218.imageshack.us/img218/4670/last800knaant.png
From Peru says:
“…in a century we are back, in Greenland, to the warmth of the Minoan Warming and the Holocene Maximum. That is, modern warming erased millenia of cooling.”
That is just not true. Currently we are 2 – 3° below the Minoan Optimum. The temperature has risen by a mild 0.7°C over the past century; something that has occurred repeatedly and often throughout the Holocene.
Natural climate variability completely explains the rise, with no need for an extraneous variable such as CO2 — which follows rises in temperature. Effect cannot precede cause, and the climate null hypothesis has never been falsified. What we are observing is natural and routine.
It is coincidental that there has been a 0.7° rise which overlaps the ≈40% rise in CO2 [that is a substantial rise, but there is no evidence that any global harm has occurred as a result. The only observable result is increased agricultural productivity]. The rise in CO2 probably caused a fraction of that warming. But there is no testable evidence showing that the effect is more than minuscule. And the GCMs that are the basis for the bedwetters’ fright can’t predict their way out of a wet paper bag.
So, who to believe? Drs Alley and Easterbrook, who have forgotten more about climate history than someone from Peru will ever learn? Or should we believe From Peru, who makes up his facts as he goes along, and wouldn’t know the scientific method if it bit him on the ankle?
Inventing flat-out wrong statements are fine at realclimate [just so long as they support the belief system that says CO2 will cause climate catastrophe]. But making up facts doesn’t pass muster here at the internet’s “Best Science” site.
Cognitive dissonance does strange things to members of the CAGW Doomsday Cult.
Dave Springer, this crackerhead [me] thanks you for clearing that up!
Bob from the UK says:
December 30, 2010 at 1:39 am
From Peru says:
December 29, 2010 at 5:26 pm
Re the GISP2 data
It is possible to match it to present day data – it has been done previously, but I’ve just put up a guest post from a guy who wanted to investigate it himself, and got a few pointers – from NCDC no less! http://diggingintheclay.wordpress.com/2010/12/30/dorothy-behind-the-curtain-part-2/
From his analysis GISP2 the temperature in Central Greenland approximates to that of the Minoan Warm Period, although I did find an older paper with the GRIP and DYE 3 ice cores where the current temperature is closer to the Medieval Warm Period.
Do you? According to the GISP2 data we had warming from -46C to -36C in the 200 years from 9750 to 9550 BC. That makes the 2.5C warming of the Greenland coastal regions in the 50 years from 1880 to 1930 look pretty normal.