Easterbrook on the magnitude of Greenland GISP2 ice core data

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MAGNITUDE AND RATE OF CLIMATE CHANGES

Guest post by Dr. Don J. Easterbrook,

Dept. of Geology, Western Washington University

The GISP2 Greenland ice core has proven to be a great source of climatic data from the geologic past. Ancient temperatures can be measured using oxygen isotopes in the ice and ages can be determined from annual dust accumulation layers in the ice. The oxygen isotope ratios of thousands of ice core samples were measured by Minze Stuiver and Peter Grootes at the University of Washington (1993, 1999) and these data have become a world standard.

The ratio of 18O to 16O depends on the temperature at the time snow crystals formed, which were later transformed into glacial ice. Ocean volume may also play a role in δ18O values, but δ18O serves as a good proxy for temperature. The oxygen isotopic composition of a sample is expressed as a departure of the 18O/16O ratio from an arbitrary standard

δ18O =

(18O/16O)sample ‒ (18O/16O) x 103

____________________________________

(18O/16O)standard

where δ18O is the of ratio 18O/16O expressed in per mil (0/00) units.

The age of each sample is accurately known from annual dust layers in the ice core. The top of the core is 1987.

The δ18O data clearly show remarkable swings in climate over the past 100,000 years. In just the past 500 years, Greenland warming/cooling temperatures fluctuated back and forth about 40 times, with changes every 25-30 years (27 years on the average). None of these changes could have been caused by changes in atmospheric CO2 because they predate the large CO2 emissions that began about 1945. Nor can the warming of 1915 to 1945 be related to CO2, because it pre-dates the soaring emissions after 1945. Thirty years of global cooling (1945 to 1977) occurred during the big post-1945 increase in CO2.

But what about the magnitude and rates of climates change? How do past temperature oscillations compare with recent global warming (1977-1998) or with warming periods over the past millennia. The answer to the question of magnitude and rates of climate change can be found in the δ18O and borehole temperature data.

Temperature changes in the GISP2 core over the past 25,000 years are shown in Figure 1 (from Cuffy and Clow, 1997). The temperature curve in Figure 1 is a portion of their original curve. I’ve added color to make it easier to read. The horizontal axis is time and the vertical axis is temperature based on the ice core δ18O and borehole temperature data. Details are discussed in their paper. Places where the curve becomes nearly vertical signify times of very rapid temperature change. Keep in mind that these are temperatures in Greenland, not global temperatures. However, correlation of the ice core temperatures with world-wide glacial fluctuations and correlation of modern Greenland temperatures with global temperatures confirms that the ice core record does indeed follow global temperature trends and is an excellent proxy for global changes. For example, the portions of the curve from about 25,000 to 15,000 represent the last Ice Age (the Pleistocene) when huge ice sheets thousands of feet thick covered North America, northern Europe, and northern Russia and alpine glaciers readvanced far downvalley.

So let’s see just how the magnitude and rates of change of modern global warming/cooling compare to warming/cooling events over the past 25,000 years. We can compare the warming and cooling in the past century to approximate 100 year periods in the past 25,000 years. The scale of the curve doesn’t allow enough accuracy to pick out exactly 100 year episodes directly from the curve, but that can be done from the annual dust layers in ice core data. Thus, not all of the periods noted here are exactly 100 years. Some are slightly more, some are slightly less, but they are close enough to allow comparison of magnitude and rates with the past century.

Temperature changes recorded in the GISP2 ice core from the Greenland Ice Sheet (Figure 1) (Cuffy and Clow, 1997) show that the global warming experienced during the past century pales into insignificance when compared to the magnitude of profound climate reversals over the past 25,000 years. In addition, small temperature changes of up to a degree or so, similar to those observed in the 20th century record, occur persistently throughout the ancient climate record.

Figure 1. Greenland temperatures over the past 25,000 years recorded in the GISP 2 ice core. Strong, abrupt warming is shown by nearly vertical rise of temperatures, strong cooling by nearly vertical drop of temperatures (Modified from Cuffy and Clow, 1997).

Figure 2 shows comparisons of the largest magnitudes of warming/cooling events per century over the past 25,000 years. At least three warming events were 20 to 24 times the magnitude of warming over the past century and four were 6 to 9 times the magnitude of warming over the past century. The magnitude of the only modern warming which might possibly have been caused by CO2. (1978-1998) is insignificant compared to the earlier periods of warming.

Figure 2. Magnitudes of the largest warming/cooling events over the past 25,000 years. Temperatures on the vertical axis are rise or fall of temperatures in about a century. Each column represents the rise or fall of temperature shown on Figure 1. Event number 1 is about 24,000years ago and event number 15 is about 11,000 years old. The sudden warming about 15,000 years ago caused massive melting of these ice sheets at an unprecedented rate. The abrupt cooling that occurred from 12,700 to 11,500 years ago is known as the Younger Dryas cold period, which was responsible for readvance of the ice sheets and alpine glaciers. The end of the Younger Dryas cold period warmed by 9°F ( 5°C) over 30-40 years and as much as 14°F (8°C) over 40 years.

Magnitude and rate of abrupt climate changes

Some of the more remarkable sudden climatic warming periods are shown listed below (refer also to Figure 1). Numbers correspond to the temperature curves on Figure 5.

1. About 24,000 years ago, while the world was still in the grip of the last Ice Age and huge continental glaciers covered large areas, a sudden warming of about 20°F occurred. Shortly thereafter, temperatures dropped abruptly about 11°F. Temperatures then remained cold for several thousand years but oscillated between about 5°F warmer and cooler.

2. About 15,000 years ago, a sudden, intense, climatic warming of about 21°F (~12° C;) caused dramatic melting of the large ice sheets that covered Canada and the northern U.S., all of Scandinavia, and much of northern Europe and Russia.

3. A few centuries later, temperatures again plummeted about 20° F (~11°C) and glaciers readvanced.

4. About 14,000 years ago, global temperatures once again rose rapidly, about 8° F (~4.5°C), and glaciers receded.

4. About 13,400 years ago, global temperatures plunged again, about 14° F (~8°C) and glaciers readvanced.

5. About 13,200 years ago, global temperatures increased rapidly, 9° F (~5°C), and glaciers receded.

6. 12,700 yrs ago global temperatures plunged sharply, 14° F (~8°C) and a 1300 year cold period, the Younger Dryas, began.

7. After 1300 years of cold climate, global temperatures rose sharply, about 21° F (~12° C), 11,500 years ago, marking the end of the Younger Dryas cold period and the end of the Pleistocene Ice Age.

Early Holocene climate changes

8,200 years ago, the post-Ice Age interglacial warm period was interrupted by a sudden global cooling that lasted for a few centuries (Fig. 3). During this time, alpine glaciers advanced and built moraines. The warming that followed the cool period was also abrupt. Neither the abrupt climatic cooling nor the warming that followed was preceded by atmospheric CO2 changes.

Figure 3. The 8200 year B.P. sudden climate change, recorded in oxygen isotope ratios in the GISP2 ice core, lasted about 200 years.

Late Holocene climate changes

750 B.C. to 200 B.C. cool period

Prior to the founding of the Roman Empire, Egyptians records show a cool climatic period from about 750 to 450 B.C. and the Romans wrote that the Tiber River froze and snow remained on the ground for long periods (Singer and Avery, 2007).

The Roman warm period (200 B.C. to 600 A.D.)

After 100 B.C., Romans wrote of grapes and olives growing farther north in Italy than had been previously possible and of little snow or ice (Singer and Avery, 2007).

The Dark Ages cool period (440 A.D. to 900 A.D.)

The Dark Ages were characterized by marked cooling. A particularly puzzling event apparently occurred in 540 A.D. when tree rings suggest greatly retarded growth, the sun appeared dimmed for more than a year, temperatures dropped in Ireland, Great Britain, Siberia, North and South America, fruit didn’t ripen, and snow fell in the summer in southern Europe (Baillie in Singer and Avery, 2007). In 800 A.D., the Black Sea froze and in 829 A.D. the Nile River froze (Oliver, 1973).

The Medieval Warm Period (900 A.D. to 1300 A.D.)

The Medieval Warm Period (MWP) was a time of warm climate from about 900–1300 AD when global temperatures were apparently somewhat warmer than at present. Its effects were particularly evident in Europe where grain crops flourished, alpine tree lines rose, many new cities arose, and the population more than doubled. The Vikings took advantage of the climatic amelioration to colonize Greenland, and wine grapes were grown as far north as England where growing grapes is now not feasible and about 500 km north of present vineyards in France and Germany. Grapes are presently grown in Germany up to elevations of about 560 meters, but from about 1100 to 1300 A.D., vineyards extended up to 780 meters, implying temperatures warmer by about 1.0 to 1.4° C (Oliver, 1973, Tkachuck, 1983). Wheat and oats were grown around Trondheim, Norway, suggesting climates about one degree C warmer than present (Fagan, 2007).

The Vikings colonized southern Greenland in 985 AD during the Medieval Warm Period when milder climates allowed favorable open-ocean conditions for navigation and fishing. This was “close to the maximum Medieval warming recorded in the GISP2 ice core at 975 AD (Stuiver et al., 1995).

Elsewhere in the world, prolonged droughts affected the southwestern United States and Alaska warmed. Sediments in Lake Nakatsuna in central Japan record warmer temperatures. Sea surface temperatures in the Sargasso Sea were approximately 1°C warmer than today and the climate in equatorial east Africa was drier from 10001270 AD. An ice core from the eastern Antarctic Peninsula shows warmer temperatures during this period.

The Little Ice Age (1300 A.D. to the 20th century)

At the end of the Medieval Warm Period, ~1230 AD, temperatures dropped ~4°C (~7° F) in ~20 years and the cold period that followed is known as the Little Ice Age. The colder climate that ensued for several centuries was devastating (see e.g., Grove, 1988, 2004; Singer and Avery, 2007; Fagan, 2000). Temperatures of the cold winters and cool, rainy summers were too low for growing of cereal crops, resulting in widespread famine and disease. When temperatures declined during the 30–year cool period from the late 1940’s to 1977, some climatologists and meteorologists predicted a return to a new Little Ice Age.

Glaciers expanded worldwide (see e.g., Grove, 1988, 2004; Singer and Avery, 2007). Glaciers in Greenland advanced and pack-ice extended southward in the North Atlantic in the 13th century. The population of Europe had become dependent on cereal grains as a food supply during the Medieval Warm Period and when the colder climate, early snows, violent storms, and recurrent flooding swept Europe, massive crop failures occurred. Three years of torrential rains that began in 1315 led to the Great Famine of 1315-1317. The Thames River in London froze over, the growing season was significantly shortened, crops failed repeatedly, and wine production dropped sharply (Fagan, 2000; Singer and Avery, 2007).

Winters during the Little Ice Age were bitterly cold in many parts of the world. Advance of glaciers in the Swiss Alps in the mid–17th century gradually encroached on farms and buried entire villages. The Thames River and canals and rivers of the Netherlands frequently froze over during the winter. New York Harbor froze in the winter of 1780 and people could walk from Manhattan to Staten Island. Sea ice surrounding Iceland extended for miles in every direction, closing many harbors. The population of Iceland decreased by half and the Viking colonies in Greenland died out in the 1400s because they could no longer grow enough food there. In parts of China, warm weather crops that had been grown for centuries were abandoned. In North America, early European settlers experienced exceptionally severe winters.

Significance of previous global climate changes

If CO2 is indeed the cause of global warming, then global temperatures should mirror the rise in CO2. For the past 1000 years, atmospheric CO2 levels remained fairly constant at about 280 ppm (parts per million). Atmospheric CO2 concentrations began to rise during the industrial revolution early in the 20th century but did not exceed about 300 ppm. The climatic warming that occurred between about 1915 and 1945 was not accompanied by significant rise in CO2. In 1945, CO2 emission began to rise sharply and by 1980 atmospheric CO2. had risen to just under 340 ppm. During this time, however, global temperatures fell about 0.9°F (0.5° C) in the Northern Hemisphere and about 0.4°F (0.2° C) globally. Global temperatures suddenly reversed during the Great Climate Shift of 1977 when the Pacific Ocean switched from its cool mode to its warm mode with no change in the rate of CO2 increase. The 1977–1998 warm cycle ended in 1999 and a new cool cycle began. If CO2 is the cause of global warming, why did temperatures rise for 30 years (1915-1945) with no significant increase in CO2? Why did temperatures fall for 30 years (1945-1977) while CO2 was sharply accelerating? Logic dictates that this anomalous cooling cycle during accelerating CO2 levels must mean either (1) rising CO2 is not the cause of global warming or (2) some process other than rising CO2 is capable of strongly overriding its effect on global atmospheric warming.

Temperature patterns since the Little Ice Age (~1300 to 1860 A.D.) show a very similar pattern; 25–30 year–long periods of alternating warm and cool temperatures during overall warming from the Little Ice Age low. These temperature fluctuations took place well before any significant effect of anthropogenic atmospheric CO2.

Conclusions

Temperature changes recorded in the GISP2 ice core from the Greenland Ice Sheet show that the magnitude of global warming experienced during the past century is insignificant compared to the magnitude of the profound natural climate reversals over the past 25,000 years, which preceded any significant rise of atmospheric CO2. If so many much more intense periods of warming occurred naturally in the past without increase in CO2, why should the mere coincidence of a small period of low magnitude warming this century be blamed on CO2?

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I presume the question in the conclusion is rhetorical. The real answer is that it shouldn’t be. The actual answer is quite different and very sad.

Vince Causey

This is a really excellent post, and puts our current warming into a historical perspective. It is a quirk of history that we are now in a warming period instead of a cooling period.

RHS

The only “thing” which has changed through the course of time is the conscience of man. We are, we create, we consume, therefore, we induce change. We have too many people studying small insignificant problems/we don’t have enough large problems to solve.
Understanding change/impact is one thing, assuming the sky is falling before understanding the problems in general is another.
Looks like another great work which won’t see enough sunlight…
Which is too bad because I really like the climatic tie-ins to actual and recorded history.

Robuk
TheSkyIsFalling

The Vikings took advantage of the climatic amelioration to colonize Greenland, and wine grapes were grown as far north as England where growing grapes is now not feasible

I enjoyed the article, thanks. But this will come as news to the English wine industry – the south of England currently has many vineyards.

“If so many much more intense periods of warming occurred naturally in the past without increase in CO2, why should the mere coincidence of a small period of low magnitude warming this century be blamed on CO2?”
There’s no scientifically testable scientific answer to that question, Doc. I suspect it has to do with human gullibility and desire for certainty. Promoters of warming based on anthropogenic CO2 exploit that gullibility and desire.

Patvann

Perfect.

steveta_uk

Why no graph for the Late Holocene period? You seem to switch from real data to historical prose.

TerrySkinner

Many thanks for that. Not that it will make any difference to the true believers in Anthropogenic Global Warming for whom ‘science’ is always on their side.

GregL

Isn’t it a stretch to present Greenland ice cap temperature as global temperature?

Hoser

It’s also interesting to see the 10Be data from GISP2. I’m going to try to insert the image here (ripped quickly from XL). And I’ll have the link below that if the image doesn’t show up. The x axis is years (0 is today). The Y axis is 10^3 10Be/g of ice.
http://knxu.com/~pix/10Be_Greenland_ice_core.gif
You can see the Younger Dryas signal here. It is not clearly seen in the antarctic cores. Also, the LIA 10Be values are very low compared to those from the Ice Age. I don’t see how a ‘quiet’ sun could be the only modulator of GCRs. It seems more likely the GCR flux is variable outside the control of the sun. Which also suggests the Milankovic cycles are not the whole story.

Doctor Gee

Very interesting piece. When taking ice cores, what process is used to delineate/differentiate the oxygen content of individual “layers” to break out estimates of the years that they represent? How thick (or thin) a “slice” of an ice core can be assayed in any given sample and how are variations in thickness/deposition over time accounted for? Given the various warm spikes that occurred over time, what measures can be taken to ensure that melting (not to mention shearing and other physical effects) don’t compromise the dating of the analytical measurements.
Signed,
– An inquiring (and presently ignorant) mind

Anoneumouse

@GregL
Bingo

Robuk

GregL says:
January 24, 2011 at 10:26 am
Isn’t it a stretch to present Greenland ice cap temperature as global temperature?
Are you copmparing that with this.
We found that although the Gaspe series begins in 1404, up until 1421, it is based on only one tree.
http://www.junkscience.com/jan05/lone_gaspe_cedar.html

Hal

Where were the Greenland ‘Greenies’ eons ago? The scientific consensus of that day would have dictated the ‘correct’ human inputs and outputs, and the tropical paradise of Greenland could have been preserved.

John B

Great post, thanks

don penman

I think that the most northerly place in England where wines is produced from grapevines is Lincoln or so we were told.I hate to think how those vines have fared in the recent cold weather.I planted a grape vine myself and it flourished It produced a large amount of grapes over several years. The height above sea level though as mentioned in this post is probably important but I think that the grape vine is more hardy then some people think particularly those from Germany.

KD

GregL says:
January 24, 2011 at 10:26 am
Isn’t it a stretch to present Greenland ice cap temperature as global temperature?
_______________
Please define “global temperature” as precisely as you can and how to measure it.
Also, please provide the reasoning as to why temperature changes in Greenland would be significantly different than in other parts of the world and whether those changes would be more or less dramatic than elsewhere.

James Sexton

The reiteration of recorded history, IMHO, is much more convincing than a sampling of ice.
Dr. Easterbrook, how does one differentiate the H2O that had froze, then melted, then froze again several more times, from the more simple H20 that maybe only refroze a couple of times? Does melting and refreezing change the isotope configuration? And doesn’t particulate move through ice? I don’t mean to be a wet blanket, but its hard for me to wrap my head around the dating and the isotope ratio stuff. That said, if it is consistent with recorded history, then it would be a powerful correlation. Thanks for the posting!

George E. Smith

Don,
I’m having a hard time trying to understand how Oxygen transmutes from one atomic weight to another just based on Temperature. Are they measuring actual atmospheric O2 trapped in the ice along with the trapped CO2 ? Or are they measuring the Oxygen in the H2O molecules of the ice itself and what about the Oxygen in the entrapped CO2. I would think they could get C18O16O, along with C18O2, or C16O2, and then there’s the H2 or D2 or maybe HD in the water.
I really don’t understand how Temperature can affect the atomic weight of an atom species.

DJ

I have to disagree with the concept that Greenland ice cores can be a valid proxy on their own for global temperature. While it may be a good indicator, the full picture can only be seen with an attendant show of comparable antarctic ice cores. Maybe I’m arguing for what will result in only a degree of accuracy, but I believe it better to withstand opposition.
What happens on both poles, not just one, is a better perspective of the globe as a whole.

Louise

Dr Easterbrook – in 2001 you wrote “If the cycles continue as in the past, the current warm cycle should end in the next few years, and global warming should abate, rather than increase, in the coming decades.” http://gsa.confex.com/gsa/2001AM/finalprogram/abstract_28039.htm
Bearing in mind that 2010 has tied for the warmest year on record with 1998 (See http://www.drroyspencer.com/2011/01/dec-2010-uah-global-temperature-update-0-18-deg-c/), can you please explain when you expect this global cooling to begin?

DaveF

Don Penman 10:53am
Many years ago I lived in the South of France, but some distance from the sea. Hard frosts were common in the winter, but the vines didn’t mind. I was told that the vines are quite hardy to frost but what is crucial is the amount of warmth and sunshine they get in summer to produce the necessary sugars. So cold winters are ok but cool summers mean you don’t get much wine.

And….kind of political question: what does come next?

Sal Minella

How accurate is ice core record dating? From the article, one could assume that dust layers are used to indicate annual boundaries. Is it not possible that ice layers might not be formed for decades, centuries, or millenia during warmer periods? If so, there would appear to be large jumps in global temperature. Is a secondary method like carbon dating used to verify core age?

RACookPE1978

Louise says:
January 24, 2011 at 11:18 am (Edit)

Dr Easterbrook – in 2001 you wrote “If the cycles continue as in the past, the current warm cycle should end in the next few years, and global warming should abate, rather than increase, in the coming decades.”
Bearing in mind that 2010 has tied for the warmest year on record with 1998 (See http://www.drroyspencer.com/2011/01/dec-2010-uah-global-temperature-update-0-18-deg-c/), can you please explain when you expect this global cooling to begin?

—…—…
Louise,
Given that global temperatures have not increased for the past twelve years (now over 1/3 of a “climate cycle” of 30 years – while CO2 has steadily increased, when will (anthropogenic) global warming begin?
Given that temperatures rose equally fast for equally as long between 1890 and 1940 – when CO2 was steady at 280 ppm – when will CO2 begin affecting global temperatures?
Given that CO2 was rising while temperatures decreased for 33 years between 1940 and 1973, when will CO2 begin affecting global temperatures?
All I can find is a 350 year natural climb up from the Little Ice Age, combined with a natural 66 year cycle that peaked 2000 – 2010.
Yes, we are now in a (naturally-occurring) flat spot of warm temperatures from 1998 – through 2031. then we (might) rise again for 33 years. Or we might have peaked the Modern Warming Period today, and already be sliding back down into the hazards and death of the Modern Ice Age.
And hopefully, NOT the next Modern Glacier Age. Which is overdue.

Old England

Good article – one minor correction I am aware of:
Under MWP it is stated : “wine grapes were grown as far north as England where growing grapes is now not feasible”. Not so :-
In Roman times grapes were grown as far up as parts of the North of England. In the latter half of the 20th century vineyards were established in the south of England and later in the midlands. English sparkling wines and particularly those grown on chalk, similar to champagne region of France, have won many awards over champagne in France and are a normal feature in Royal banquets – particularly when entertaining foreign heads of state.
Lots of details on english vineyards here for anyone who is interested in them or their geographic spread within the UK: http://www.englishwineproducers.com/

Louise

Dr Easterbrook, you said in 2009 “Beginning this year, global cooling will cause crop failures and serious food shortages” at http://www.heartland.org/bin/media/newyork09/PowerPoint/Don_Easterbrook.ppt#608,49,Implications
Does this mean that you think the Russian heatwave, Pakistan flood, Australian drought and flood (all of which may have contributed to food shortages) are as a result of global cooling?

George,
They are measuring the depletion in the ice of the heavier isotope from a sea water standard. Multiple cycles of evaporation/condensation in route from the equator to Greenland fractionates the lighter from the heavier. They are not measuring changes in the trapped air. http://www.kidswincom.net/climate.pdf.

Louise

[Snip. Calling Dr Easterbrook a “fraud” is not appreciated. ~dbs, mod.]

P.F.

Dark Ages cool period: David Keys pegged that to the Sunda Caldera pyroclastic event around 535 with convincing evidence. Ref: Catastrophe, An investigation into the origins of the modern world. 1999 ISBN 0-345-40876-4

NormD

So why do global temperatures change?
Is there some model that explains the changes?
Instead of just arguing that CO2 is not the primary driver of global temperature, it would be nice is there was a competing model that explained temperature with CO2 in its proper role.
For those that say that “global temperature” is a meaningless term, when we say the Earth is experiencing an “ice age” are not we implying that the Earth is much cooler than at other times? Perhaps we cannot measure global temperature in an absolute sense, but surly we can speak of relative temperatures.

Paul Loock

George E. Smith says:
January 24, 2011 at 11:03 am

“I really don’t understand how Temperature can affect the atomic weight of an atom species.”
O16 and O18 are natural isotopes of oxygen. Water containing O18 has different boiling and freezing temperatures than normal O16-Water. The differences in vapor and snow depend on temperatures during evaporation of water from the sea and condensation to snow.

It is absolute rubish to attribute delta-18O to temperature. As a part of my Ice Core series, I have produced a page explaining exactly why.
Basically, Vostok data for the last 420,000 years shows 4 interglacials using deuterium data, and 11 using delta-18O data. This discrepancy proves that one of these proxies is NOT a temperature proxy.
As always, please obtain and plot this data yourself. In science, don’t trust anything that can not be replicated.

klem

“Isn’t it a stretch to present Greenland ice cap temperature as global temperature?”
Absolutely correct, it is. The IPCC has been using the Greenland ice cores temperatures and calling them global for years.

Louise says:
“Does this mean that you think the Russian heatwave, Pakistan flood, Australian drought and flood (all of which may have contributed to food shortages) are as a result of global cooling?”
Does that mean you believe a minor trace gas is the cause?
Such natural fluctuations have always happened. They are the result of natural climate variability. Nothing out of the ordinary is happening.

MattN

Very nice. Thanks for the post. Will this info be published?

DirkH

Louise says:
January 24, 2011 at 11:37 am
“Does this mean that you think the Russian heatwave, Pakistan flood, Australian drought and flood (all of which may have contributed to food shortages) are as a result of global cooling?”
Louise, you’re trolling. Heatwaves in summer in Russia are common; Monsoon rains in Pakistan as well (i read that in this Monsoon season 5% more rain came down than usual; the problem was more with the dykes it seems). Australia *always* has drought or flood.

roger

Old England says:
January 24, 2011 at 11:29 am
I don’t know about vines growing in northern England, but here in southern Scotland, on the Solway coast, I do know that since the early 1990’s I have left my dahlias to overwinter with impunity. Never a one was lost as a result of frost.
Last winter and again this winter, the frosts were so severe and of such duration that every tuber turned to a suparating mush, and yet again I must replace them at some considerable cost. Causality? Laziness, rather than a damascene conversion to the Global church of Disruption.
Perhaps Louise and the other two trolls above would like to explain when they expect this global warming to begin, or are they just parroting the discredited psuedo- science of the team?
Should I lift and store my dahlias this autumn? What do you think?
http://weather.unisys.com/surface/sst_anom.gif

GregL

KD says:
January 24, 2011 at 10:56 am
Please define “global temperature” as precisely as you can and how to measure it.
*** I’m not the one using the term, the article said: “Temperature changes recorded in the GISP2 ice core from the Greenland Ice Sheet (Figure 1) (Cuffy and Clow, 1997) show that the global warming experienced during the past century pales into insignificance when compared to the magnitude of profound climate reversals over the past 25,000 years.” There is no explanation of how to get from one to the other. ***
Also, please provide the reasoning as to why temperature changes in Greenland would be significantly different than in other parts of the world and whether those changes would be more or less dramatic than elsewhere.
*** You seem to assume that the relationship of Greenland icecap temperature to global temperature is a constant across all climate states. That is wrong. If it were right, then we could measure today’s global temperature with one reading at one location and extrapolate to the global. but the noise at each location causes it’s temperature to move differently from other locations.
Here is the simplest and most telling point. At the glacial maximum, the sheer presence of the huge ice sheets (predominately in the NH) and the global drop in sea level by ~120 meters caused wind circulation to be different from today. To expect the pattern of temperatures around the world to remain constant under such a massive difference is folly.
Here is the second simplest point. The change in orbit over 25,000 years causes the solar isolation distribution to vary. To expect no change in the spacial distribution of temperature differentials by latitude and hemisphere would also be folly.***

mkelly

GregL says:
January 24, 2011 at 10:26 am
Isn’t it a stretch to present Greenland ice cap temperature as global temperature?
“Keep in mind that these are temperatures in Greenland, not global temperatures. However, correlation of the ice core temperatures with world-wide glacial fluctuations and correlation of modern Greenland temperatures with global temperatures confirms that the ice core record does indeed follow global temperature trends and is an excellent proxy for global changes.”
GregL try reading the article.

Sal Minella

To ask the question in a different way: Is it assumed that there were no periods of melting or no ice formation in Greenland over the period that the ice cores represent?
If there were such periods, would these periods appear as abrupt changes in global temperature? If there was no ice formed during these periods, how do we know how long they were? Doesn’t this cast doubt on the utility of the ice record?
These are not rhetorical questions, I really would like answers. Thanks

Chad Woodburn

GregL says:
January 24, 2011 at 10:26 am
Isn’t it a stretch to present Greenland ice cap temperature as global temperature?
______________
Of course that would be a stretch. That is why this articile does nothing of the sort. It presents the Greenland temperatures based on ice cores, and then correlates that with the history of other climate trends in the rest of the world. True, the Greenland ice cap doesn’t tell us about the Nile freezing (etc.), but the Greenland ice cap record fits in with much of the rest of the climate record throughout history.

The geologists perspective is valuable in confirming that what we see happening today is nothing unusual.
I want to point readers towards an explanation of the 27-30 year cycle of temperature in the Greenland ice core that continues to this day. It is a hemisphere wide phenomenon.
This explanation focuses on the swings in the Arctic Oscillation. In its simplest and most meaningful definition the Arctic Oscillation involves a thirty year decline in atmospheric pressure in the Arctic followed by a thirty year increase. As pressure increases the westerlies that ‘prevail’ in the mid latitudes stop ‘prevailing’ along with the trade winds. The polar easterlies become more evident. More frequent ‘Arctic Outbreaks occur’ in winter affecting all landmasses in the northern hemisphere. The temperature of the northern hemisphere and the Arctic in particular follows this cycle as is evident in surface temperature data.
See the explanation here:
http://climatechange1.wordpress.com/2011/01/04/something-topical-2/
The notion of man caused warming is not based on science and one can not fight it with science. Superstition and fakery is what it is all about and it is actively promoted in our educational institutions. It is the new state religion. People make money out of it and it makes them feel ‘holier’. Its the most recent manifestation of the ‘crusade’. So, many people feel a lot better if they support this thing. You wont take that away from them easily. You need something else to replace it.

max_b

Don Easterbrook’s website was one of the first I came across when I started investigating AGW some years back. I still find his Greenland temperature plots very sobering…

CET, Loehle 2008, GISP2 are the best antidote against any hockey stick.
Keep in mind that GISP2 ends in 1905, but it is a good proxy for North Atlantic/NH.

jaypan

This is an easy-to-understand piece of information.
IMHO, even for politicians.
Can’t we send it out to all those hyper-ventilating governments?
Thanks, Dr. Easterbrook

higley7

“For the past 1000 years, atmospheric CO2 levels remained fairly constant at about 280 ppm (parts per million). Atmospheric CO2 concentrations began to rise during the industrial revolution early in the 20th century but did not exceed about 300 ppm. ”
we have 200 years of Co2 chemical bottle data that show that CO2 has fluctuated greatly, above 440 ppm and up to 550 at times during three periods of the last 200 years. The 280 ppm is from ice cores that are reputedly 30-50% off from the real values. These cores are traumatized during extraction. If the 30-50% error is corrected, it puts values right in the range and even higher than today – the same range as the bottle data show. This correct has been shown valid by other means as well.
It is the IPCC which unilaterally discounted all bottle data except for two French papers which used a terrible sulfuric acid methods which is known to produce low values.
The temperature of the oceans drives the CO2 level. Alarmists standardly over-estimate our contribution and claim a 200-1000 year half-life for CO2 when the real value is more like 3-15 years. The published average is 5.4 years – this is a totally difference value but does reflect the fact that monthly CO2 data currently shows seasonal changes which should not be seen if the half-life was what the alarmists claim.

phil wright

@ louise
the global temperature anomaly has now gone negative,wiping out all of last year’s ‘warmest year ever,second warmest year ever,etc.
phil(uk)