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.
I agree with the basic premise of the article – i.e. that the ‘warmest year’ title is somewhat irrelevant and also, that it is demonstrably so. Even allowing for errors in the ice cores, tree rings, NH and SH variations, etc, etc – it (palaeoclimatology) still all points to one thing – climate has and will continue to vary, by quite large amounts – lets say +/- 5deg C – and ALL without any anthgropogenic influence ! (I am assuming that folk aren’t going to believe that aliens came in the past and burnt fossil fuels! )
While we all appear to be arguing the toss over GISSes, HADCruts, Graphs and things, has nobody, but nobody noticed that the IPCC definition of GHG Forcing flux does NOT comply with the laws of thermodynamics? Surely a flux which crosses a boundary between two systems without a ‘Change of State’ occurring in the recipient system is just nonsense? This sort of flux wouldn’t even boil a kettle let alone warm up the planet.
This has created great confusion with me as I am quite unable to follow the logic of the IPCC thereafter.
For instance: Where do I put this IPCC Forcing Flux [IPCCFF] into the Stefan-Boltzmann equation? After all, this, I understand, is used as a basis for the calculation of the temperature of all the heavenly bodies; is it not? Putting it in as an addition to Insolation offends my intuition; so where? This could perhaps be called the ‘Stefan Anomaly’
Secondly I have grave doubts about the way the Arrhenius derivative equation has been used. Implicit in this equation is the ‘All things being equal’ assumption, which is manifestly untrue; and it further suffers from ‘Argument from the particular to the general’.
Thirdly I find that the IPCC treatment of the Bode equation does NOT concur with engineering textbooks on feedback control design. However I am no expert in that field; but merely note that when the graph is plotted for various feedback parameters, using IPCC figures, it results in a totally unstable situation where, if applied to our climate would have resulted in the planet blowing up a couple of times in past history.
If, as I suspect, the IPCC logical route is so flawed then why do we not deal with this instead of looking at the trees instead of the wood?
Would it not be preferable to define the GHG effect in terms of ‘Change of State’, rather than as a flux?
Meanwhile I remain in contempt of the IPCC stance; but would dearly like to have the opinion of others on these matters.
Paul Vaughan says:
December 28, 2010 at 9:22 pm
Jantar, did you notice the word “Global” on the y-axis?
You appear to have accidentally conflated the USA with the globe.
Paul, you may be right. I seem to recall shortly after the initial Y2K error was pointed out to GISS that the global temp for 1934 was only 0.14 C lower than the USA temp. However I have been unable to find that data now, so maybe my memory is incorrect on that point.
Rob R says:
December 29, 2010 at 1:55 am
Thanks for the explanation.
There are two sets of problems in dealing with this information.
The first is in establishing the accuracy of this method of estimated temperatures from very old ice samples.
The second problem is in establishing how much the instrumental global indexes are contaminated by the UHI effect at the different locations from which the indexes are drawn and whether there are other systematic errors in these indexes, as some critics suggest.
I have found a great disparity in the rate of temperature change between global indices and certain widely disbursed individual Australian locations after adjusting for UHI (which I have been able to identify specifically). After adjustment for UHI, there is no trend in temperature over periods well in excess of 100 years. Yes I know, Australia only occupies a tiny part of the globe, but isn’t it strange that more and more individual locations in different countries and continents show the same pattern?
So I think that we all need to keep quite calm with clear heads and examine what happens in the next few years, before being absolutely, definitely sure that the earth is about to burn up (AGW) or turn into one giant deep freezer (sunspot minimum).
Now like everybody else reading this blog, I have a definite view on these matters. But in evaluating evidence we must strive to keep an open mind.
The temperature is either going up or down or staying much the same. We certainly do live in interesting times as the direction will very likely soon become obvious and at least half of us will be wrong.
Let’s hope when that comes we have the guts to acknowledge the truth.
this is interesting but just one location, why choose one ice core when there are many available now, and why call 1934 the warmest year when that was only the case in the US?
To say “1934 has long been considered the warmest year of the past century” without understanding that this refers to the US only is unforgivably ignorant.
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.
Professor Easterbrook
Current state of understanding is that causes of PDO and AMO are not known.
I think there may be a plausible cause to both.
According to my research the PDO driver reached minimum in 1973
1969 – 19
1970 – 17
1971 – 17
1972 – 15
1973 – 12
1974 – 14
1975 – 17
1976 – 17
1977 – 17
1978 – 19
1979 – 20
1980 – 25
1981 – 28
1982 – 30
Change took some 4 years (ref. your date of 1977) to propagate across Pacific. Similar minimum value (11) was previously recorded in 1942, and has not reoccurred since 1973. Although PDO is de-trended, there is a gradient to the driver as in y = 0.172x for 1860-2010.
For more details see:
http://www.vukcevic.talktalk.net/NPG.htm
http://www.vukcevic.talktalk.net/NAP-AMO.htm
Any comment welcome.
Some hippies don’t seem to realize what the higher temperatures in Greenland’s history indicates. which apparently, essentially, is that the ice didn’t melt.
However, maybe, the hippies are so mind boggled by the sheer enormity of the red bars they all went into timed manic crescendo of O. M. F. G. But it must really have been cold someplace else!
JohnWho says:
December 28, 2010 at 6:52 pm
Assuming he meant “1998 and 2010″, all but GISS:
http://tinyurl.com/ybvwog9
The UAH trend since January 1998 is positive (~0.06 deg per decade) so he’s still wrong. It’s no longer cooling since 1998.
Believe WUWT as already addressed why GISS is higher than the others.
To the satisfaction of a few perhaps.
Has anyone measured the Ar/N2 ratio in the ice cores?
Keelings Ar/N2 data is rather interesting and appears to act as a signal for ocean heating. The difference in the temperature dependent partition coefficients of Ar and N2 between the atmosphere and the oceans may be a better temperature proxy that oxygen ratios.
Just to be sure everyone understands the graphs they’re seeing.
The first one purports to show two periods each of cooling and warming over the past century. Two things. First, it stops in 2000, so does not capture the 0.18 degree C rise since then. Second, the two “cooling” periods are actually closer to neutral (temps stayed the same in one, and went down 0.1 degree in the other). In contrast, the “warming” periods saw serious temp increases. Hence, the overall trend remains warm >> we’re warming during warming periods a lot more than we’re cooling during cooling periods.
The second graph stops in the mid-1900s, therefore omitting the near one degree rise since. It does not have a reference, and appears to be based on the now debunked Loehle reconstruction.
The third graph stops even earlier, it looks like around 1900, completely omitting the temp increase of the past century.
The fourth graph is based on a 1997 paper by Coffey (not “Coffy”) and Clow. Although the author labels the base line as present temp, C&C actually defined “present” as 1950 in their paper. So this graph again fails to capture recent warming. This is also a graph solely of ice core data, recording temps high up on the summit of the Greenland ice sheet. It is not a depiction of global temps.
The 5th graph from Alley is also cherry-picked. That article was considering solely the Greenland ice core data in order to analyze the Younger Dryas cold period, which occurred 12-13,000 years ago. Here’s a link to the abstract and the key graph: http://www.ncdc.noaa.gov/paleo/pubs/alley2000/alley2000.html. Yet the graph here stops some 10,000 years ago. More important, THE MOST RECENT DATA POINT IN THE ALLEY GRAPH IS 1905!! Again, the author is ignoring the last 105 years of warming (and he’s doing so in a deceptive way by labelling the last data points as the “present”).
None of the graphs show anything like the author wants you to believe, and provide very little insight into current temps.
Stevo says:
December 29, 2010 at 3:55 am
To say “1934 has long been considered the warmest year of the past century” without understanding that this refers to the US only is unforgivably ignorant.
Either “ignorant” or misleading. That apart, I think there are problems with the Easterbrook prediction of Cooling. For what it’s worth I do believe in cycles (PDO, AMO AO etc) and it’s quite possible that we have entered a “cool phase” of the PDO as Don suggests. However, if you look closely at Figure 1 it’s clear that the ‘cooling’ takes place in the first decade of the shift. See ~1880 and ~1943. There is very little cooling after, say, 1890 or 1953. If, as Don Easterbrook suggests, the shift began in 1999 we may have already had all the ‘cooling’ there is – which simply amounts to a lack of significant warming (The UAH trend since Jan 1998 is positive).
Perhaps the increase in GHGs is amplifying the warming phase while effectively negating the cooling phase. Just a thought. However, I doubt things are as simple as all that which is why we should treat these posts (even anti-AGW ones) with total scepticism.
E.M.Smith says:
December 29, 2010 at 1:54 am
A good wrap by “chiefio” that describes the heat flow that is currently occurring. This can be seen on Dr. Spencer’s blog where satellite temperatures are taken at different levels. The current sea level graphs are showing a sharp decline in temperature which is not showing yet in the higher atmosphere records.
Check out the AMSU global temp, it has fallen off a cliff.
http://discover.itsc.uah.edu/amsutemps/
Geoff Sharp says:
December 28, 2010 at 11:39 pm
The overall trend of both graphs matches nicely but don’t expect an exact match.
There is not even a ‘nice’ match.
John Finn says:
December 29, 2010 at 4:27 am
The UAH trend since January 1998 is positive (~0.06 deg per decade) so he’s still wrong. It’s no longer cooling since 1998.
Is this another AGW cherry picking exercise?
Leveraged on the 2010 El Nino values that will surely drop off dramatically in the next few months. Come back to us in 12 months and we will review the figure.
The sad fact is after continued growth of CO2 output the temperature record is still fixed at 1998. Why is it not climbing as the AGW models predicted?
Leif Svalgaard says:
December 29, 2010 at 5:07 am
There is not even a ‘nice’ match.
Perhaps not… in your universe.
Steven Mosher:
I am generally a fan of your science and I think you do a great job at doing what you do for instance, however, I think your questions are mis-placed. I think overall you put too much faith in so-called climate scientists and too much faith in their methodology. I am not a person to say that CO2 does not warm up the Earth and I do believe humans do have an impact on the Earth which we should strive to minimize as much as possible. After that, I think global warming or cooling is nothing more then a long-term weather forecasting method. It should never be used to advocate policy.
But to answer a couple of your points:
1. The temperature reconstruction of greenland needs error bars.
This is very true. It would help to have this information. Although unless they are huge I don’t think it would change this century’s status as a rather cool century.
2. Folks who moan about the “existence” of a global average should moan now.
This is not a global average though. Its just Greenland as you say in the next point…But if we are figuring out climate or long-term weather averaged out over a long-term, heck global average temp. might be as good of a way as any. Guess I agree with you on that one…
3. Greenland is not the world. If you want to characterize the whole world by one spot then take it up with the people who complain that 7000 stations is not enough.
Very true. 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.) 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.
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.
These 2 questions are political, and are not scientific whatsoever…
2. Can we do anything about it
Yes. Depends on what your political ambitions are. We could go entirely carbon free for the most part except the air we breathe without ruining society with wind-mills. Nuclear plants and electrical cars all around, combined with very limited air travel and you have it done. This is a political question though….so its opinion based.
3. should we, if we can.
I think Nuclear is a good option. For one, its just as cheap as any other power source and two we should strive to minimize our impact no matter what it might be. Electrical cars are something that we can think about after nukes are online, I don’t subscribe to peak oil, but it would be nice to have oil and petroleum around for stuff that we make out of it instead of using for fuel.
Thank you Don Easterbrook for this post. I really do appreciate all of the graphs.
On December 29, 2010 at 1:43 am, Peter Miller said: “It is always good to have a rant from someone like MVB, as it serves to remind us all exactly what alarmist ‘logic’ is all about.”
No clue what you mean by that. In my opinion, CAGW alarmists lack both logic and integrity. But my critiques were about the posted article (“2010 – where does it fit in the warmest year list? 12/28/2010 by Don J. Easterbrook), IN AND OF ITSELF. I do not disagree with the conclusion (that 2010 the warmest (even if it were so, which is unlikely) is much ado about nothing, because we have evidence that it has been similarly warm or significantly warmer during most of the last 10,000 yrs (not to mention how much warmer it was at climatic optimums in previous interglacials; also all without AGW), but I do not see a way to scientifically arrive at the conclusion from what is presented in the article above. The Fig 1 Temp graph is not calibrated to the proxy graphs for even a basic visual comparison to be made. For starters, the last 10 decades are not even on ANY of the graphs Dr. Easterbrook chose to debunk the fuss about 2010 warmth. I take issue with comparing differently smoothened datasets, comparing measured Temps and proxies, and comparing local estimates based on proxies with the estimates of ‘global average temperature’ (and the enormous uncertainties that comes with). Not putting these sorts of issues in context, or -as is the case in the article- not even mentioning these issues, I find deceptive. Two periods supposedly on a graph being compared to each other when one of the discussed periods isn’t actually on the graph is hitting a low. Just admit it.
But – for the conclusion itself- in Fig. 5: IF recent measurements were incorporated I would expect the last decade to be akin to the peak of the MWP, but – for that location where GISP2 data were collected – who knows? GISP2 was drilled at 72 36′ N, 38 30′ W, and when you look at the temperature anomaly maps….: for that particular spot both NASA GISS and NASA MODIS pretty much say the same: a value close to or slightly cooler than to the 1951-1980 mean. In other words: even if the Fig. 5 graph extended all the way to today, it’s clear that 2010 could not beat warm periods such as Roman or Minoan Warm Periods (let alone the likely peak years within those periods).
If months or even a year jump out as warmer (or cooler) in sattelite-era measurement records, then it would be helpful to show THOSE corresponding graphs, and NOT graphs on which such recent extremes are neither shown, nor comparable to the obviously smoothened proxy data, which even if similar extremes happened in included years, they wouldn’t show up.
And, as far as Peter Miller’s comment that “GISS has grossly manipulated historic temperature data is completely irrelevant”, I disagree with as well. One can make the point using paleoclimatology, but if science wasn’t being manipulated for political agenda’s, one may not even need to look so far back to illustrate the record-breaking nonsense, that is being used to “proof” AGW dogma.
“the fact that most of this inter-glacial period has been warmer than now” is not irrelevant either. It’s very relevant to the science and it does debunk the “warmest ever” nonsense well. But that “AGW cult members have been taught that because “grants are good”, then anything from Mannian maths to distorted science is also good.”, THAT is an opinion that has absolutely nothing to do with the actual science (even though it may be true; it with be more fitting in a sociology thread perhaps.). Trumpeting some global average temperature decrease over the past few months (or days – gimme a break) is as ridiculous as trumpeting the first half of 2010 (or 2010 itself – who cares) as being oh-so-unusually warm.
In about 5 years we’ll already have a much better idea how significant the effect of the most recent ocean current changes and cosmic ray influx changes are on global climates. I doubt keeping all cars running 24/7 would make a difference to keep the wrath of global cooling at bay.
John Finn says:
December 29, 2010 at 4:56 am
For what it’s worth I do believe in cycles (PDO, AMO AO etc) and it’s quite possible that we have entered a “cool phase” of the PDO as Don suggests. However, if you look closely at Figure 1 it’s clear that the ‘cooling’ takes place in the first decade of the shift. See ~1880 and ~1943. There is very little cooling after, say, 1890 or 1953. If, as Don Easterbrook suggests, the shift began in 1999 we may have already had all the ‘cooling’ there is
A strange comment….looking at the shift in the PDO at 1945 (which was during high solar activity) we can see a gradual decline in temperatures that deepened towards the late 70’s. Later in the PDO cycle the solar output dropped dramatically and the AMO also went negative to provide the perfect storm which brought the science world to a “next ice age” situation. The current situation is very close to the same scenario but this time the solar output will be greatly sustained. I don’t think you have a grasp on what controls climate.
Steven Mosher says:
December 28, 2010 at 10:46 pm
http://www.ncdc.noaa.gov/paleo/pubs/alley2000/alley2000.gif
hmm.
If your “hmm” means that even NOAA shows that it was much warmer than it is now many times in the past 10,000 years, then “hmm” indeed!
Where is peer review when you need it? This post conflates the global climate record with regional records for the US and Greenland. Then it fails to point out that “present” only goes up to 1905. Over the last 21 years, I have been the editor or reviewer for over 600 manuscripts submited for publication in peer-reviewed scientific journals (I need to keep a record for my employer). I have to say that I have never seen a submitted manuscript with such blatant errors as in this post. Even submitting a manuscript such as this would be damaging to one’s career and would certainly cause the loss of all credibility with the journal’s editor and the reviewers if any (In most cases the editor peruses a manuscript to check it’s suitability for the journal and to decide on expert reviewers. These kinds of errors and misleading comparisons would almost certainly lead to rejection by the editor, without even sending the ms. out to reviewers).
[This is a BLOG rather than a science journal. Though some entries may contain errors at least here they are not hidden. … bl57~mod]
John Finn says:
December 29, 2010 at 4:27 am
JohnWho says:
December 28, 2010 at 6:52 pm
John Finn says:
December 28, 2010 at 6:21 pm
Which dataset (UAH, RSS, GISS or HadCrut?) shows that Temperatures “have declined slightly” between 1999 and 2010. I know this “decline” fits with Don Easterbrook’s hypothesis but it just isn’t true.
Assuming he meant “1998 and 2010″, all but GISS:
http://tinyurl.com/ybvwog9
The UAH trend since January 1998 is positive (~0.06 deg per decade) so he’s still wrong. It’s no longer cooling since 1998.
Wow, now who is “cherry picking”?
Since the highest temps of 1998 we have not exceed them, so by any normal reconning we’ve slightly cooled (Except for GISS, as noted).
Believe WUWT as already addressed why GISS is higher than the others.
To the satisfaction of a few perhaps.
I’d say to the satisfaction of many. I’m just wondering why you don’t question GISS’s figures when they are not in line with the others?
If you want to continue this line of discussion, you are welcome to meet me here:
http://www.globalwarmingskeptics.info/forums/index.php