Posts Tagged ‘Holocene’


Salmon and Sea-Level

August 8, 2009

I recently wrote about  the alarmist claim that sea level rise in British Columbia is going to have a serious negative impact on their Salmon population.  An environmental activist playing at journalist wrote for the Victoria Times Colonist:

“The spectre of rising sea levels and ecological change from climate disruption show land-use plans for Vancouver Island and the B.C. coast will need to be revisited and recalibrated to account for rapid and unabated climate change.”

“‘Once set in motion, sea-level rise is impossible to stop. The only chance we have to limit sea-level rise to manageable levels is to reduce emissions very quickly, early in this century. Later it will be too late to do much,’ says senior NASA scientist Stefan Rahmstorf in a recent article for the United Nations Office for the Co-ordination of Humanitarian Affairs.”

There may be a lot of man made obstacles to Salmon survival, such as dams, over-fishing, etc., but sea-level rise is not one of them. 

Let’s get right down to the nitty-gritty.

Salmon have been around for about 500,000 to 1,000,000 years, give or take a few hundred thousand.  This is not a praticularly long time, nevertheless, Pacific Salmon diversified into multiple species, including Cherry Salmon, Sockeye Salmon, Chinook Salmon, Pink Salmon, Chum Salmon, and Coho Salmon.  There are also Atlantic Salmon and even land-locked Salmon.

Will the sea level  rise of the 21st century end the salmon’s success?  Not likely.  Take a look at these sea-level rise rates from Alaska, one of the Salmon’s primary habitats:

Yes, that right, the sea level is dropping at almost all locations where it is measured in Alaska.  So, it doesn’t look like sea level rise is likely to be much of a threat to the salmon in Alaska or British Columbia

But let’s pretend for a moment that the seas will rise dramatically over the next century, or longer.  Would the Salmon survive this dire situation?   If the past is any indication, the Salmon should pull through.  Take a good look at the graph of Holocene sea-level in the graph below. 

Image created by Robert A. Rohde / Global Warming Art.  Go to

Image created by Robert A. Rohde / Global Warming Art. Go to

Notice that from about 12,000 14,000 years ago until about 8,000 years ago the sea rose about 120 100 meters.  So, the sea level rose about 2 meters per century for 40 60 straight centuries in the recent (geologically speaking) past!  But the Salmon somehow survived.

What effect did this sea-level rise have on the Salmon’s habitat?  The movie below shows Beringia, consisting of the eastern part of Siberia and Alaska from 21,000 years ago to the present.  Look what happens from 12,000 years ago to 8,000 years ago.  I would judge that as a pretty dramatic change of the Salmon habitat.  Yet they seem to have thrived.  I think they will survive sea-level rise this century.

Barengia 21,000 years ago to present. (NOAA)

Barengia 21,000 years ago to present. (NOAA)


The Thermohaline Circulation Only Stops for Extreme, Unrealistic Models

June 4, 2009

Return to Criticisms of Al Gore’s “An Inconvenient Truth”

Gore gives a cartoon description of the ocean circulation system when he explains what has become known as the thermohaline circulation, or the meridional overturning circulation.  In his simplistic scenario the surface ocean current that flows north in the Atlantic, bringing warmth to northern Europe will be halted by melting ice from Greenland, subsequently throwing Europe into an ice age. 

Here is Gore’s explanation in his own words from the Inconvenient Truth movie:

The Earth’s climate is like a big engine for redistributing heat from the equator to the poles.  And it does that by means of ocean currents and wind currents.  They tell us, the scientists do, that the Earth’s climate is an non-linear system – just a fancy way they have of saying that the changes are not all just gradual, some of them come suddenly, in big jumps… And so, all those wind and ocean currents that have formed since the last ice age and have been relatively stable – they’re all up in the air – they change. 

And one of the ones they’re most worried about, where they’ve spent a lot of time studying the problem is in the the North Atlantic where the gulf stream comes up and meets the cold winds coming off the Arctic over Greenland and that evaporates the heat out of the gulf stream and the steam is carried over to western Europe by the prevailing winds and the Earth’s rotation.  But isn’t it interesting that the whole ocean current system is all linked together in this loop, they call it the ocean conveyor.

vlcsnap-324533And the red are the warm surface currents, the Gulf Stream is the best known of them.  But the blue represent the cold currents running in the opposite direction…

vlcsnap-32114Up in the North Atlantic, after that heat is pulled out, what’s left behind is colder water, and saltier water, because the salt doesn’t go anywhere. And so, that makes it denser and heavier.  And so that cold heavy dense water sinks at the rate of 5 billion gallons per second.  And then that pulls that current back south.ani-21

At the end of the last ice age as the last glacier was receding from North America the ice melted and a giant pool of fresh water formed in North America, and the Great Lakes are the remnants of that huge lake.  An ice dam on the eastern border formed, and one day it broke, and all that fresh water came rushing out, ripping open the St. Lawrence there, and it diluted the salty dense cold water, made it fresher and lighter so it stopped sinking, and that pump shut off.

 vlcsnap-549956-smallAnd the heat transfer stopped.  And Europe went back into an ice age for another 900 to 1000 years.  And the change from conditions like we have here today to an ice age took place in perhaps as little as ten years time.  So that’s a sudden jump.  Now, of course, that’s not going to happen again because the glaciers of North America are not there… Is there any other big chunk of ice anywhere near there…?  Oh, yeah [Gore says ominously, as the image pans to ice covered Greenland] we’ll come back to that one…

Later in the movie Gore tells us that Greenland is rapidly melting.  The point being that it will provide a massive amount of fresh water that will stop the the thermohaline conveyor and  “would raise sea level almost 20 feet if it ‘went,'” Gore tells us.  He tells us about water seeping to the bottom of the ice sheets where it “lubricates where the ice meets the bedrock” causing the ice to slide toward the ocean.

Then he shows a series of pictures purporting to show the amount of melting in Greenland.  Gore says…


“In 1992 they measured this amount of melting in Greenland … Ten years later this is what happened…And here’s the melting from 2005”


Hosing Experiments

But what if…?  What if there were a huge amount of low density fresh water dumped into the North Atlantic where the high density water is supposed to be sinking, just like the giant Canadian lake crashing through the barrier of ice the Gore told us about?  This possibility is explored with computer models known as  “hosing experiments.”  In a hosing experiment a model that simulates the ocean and atmosphere circulation patterns is modified to artificially dump huge amounts of extra fresh water, as if from a giant hose, into some location in the ocean.   It has been found that when enough fresh water is forced in, the circulation can be slowed, but rarely stopped

How much fresh water do the hosing experiments use to nearly stop the thermohaline circulation?  Typically (or here), they use one million cubic meters of fresh water per second, for 100 years!!!  (One million cubic meters per second has its own unit name: One Sverdrup or 1 Sv).  How does 1 Sv compare to, say, the rate of water flowing over Niagara Falls?

Niagara falls168,000 cubic  meters of water fall over Niagara Falls every minute.  That is about 2,800 cubic meters of water per second.  So one Sverdrup of water is the same as about 350 Niagara Falls!  (1,000,000 / 2,800  = 357).  So, roughly speaking, if 350 Niagara Falls were dumped into the oceans around Greenland continuously for 100 years, then we could expect to see a significant slow down of the thermohaline circulation.

River systems discharging into the Arctic Ocean.

River systems discharging into the Arctic Ocean.

How does one Sverdrup compare to the freshwater discharge of ALL the rivers emptying into the arctic ocean?  One Sverdrup of fresh water amounts to nearly 32,000 km3 of water per year  (1 Sv  x 106 m3 s-1/sv x (86,400 s/day) x (365 day/year) = 31,536 km3/year).  The total fresh water discharge from all rivers into the arctic is only about 4,300 km3 per year.  So, typical hosing experiments that nearly stop the overturning circulation add a water volume about 7 times the amount of water from all rivers discharing into the Arctic Ocean combined.

What about Greenland?

Hosing copyGore ominously implies that the amount of fresh water needed to turn off the overturning circulation is just waiting to pour off of  Greenland, due of course (drum roll), to CO2 induced anthropogenic global warming.   His pictures of Greenland, shown above, imply that about half of Greenland’s 2.8 million cubic kilometers of ice have melted in the 13 years between 1992 and 2005.  This is wildly misleading.  Only a miniscule fraction of the area shown in Gore’s Greenland images actually melts every year.   This is evidenced by mass balance studies, which show Greenland loses on the order of hundred cubic kilometers of ice every year,  which translates into a measly 0.003 Sverdrups.

100 km3 /year= 1011 m3/year

(1011 m3/year) / (365 days/year) / (86,400 seconds/day)
             = 3 x 103 m3/second
             = 0.003 Sv

Put another way, one Sverdrup of fresh water is 86.4 km3/day.  So the hosing experiments pouring in one Sverdrup put about as much fresh water into the ocean each day (86.4 km3) as Greenland provides in a year (100 km3).

But if Greenland actually started melting, by some extraordinary circumstance,  300 times faster, then it would yield 1 Sverdrup, or 1,000,000 cubic meters, of fresh water every second.  What would happen after 100 years of melting at that rate?  Well, that’s a trick question, because at a melting rate that gives 1 Sverdrup of freshwater Greenland would run out of ice in about 90 years.  This is because Greenland has only 2.85 million cubic kilometers of ice, and one Sverdrup of water is the same as about 31,500 cubic kilometers of water per year.  Ignoring the difference in density between ice and water, then 2.85 million cubic kilometers divided by 31,500 cubic kilometers per year gives 90 years.


You don’t hear as much about the threat of the collapse to the thermohaline circulation today as you did a few years ago.  This is because it has become recognized as being a very far fetched possibility, even by most alarmists who want to maintain a shred of dignity.  But I have a feeling we will not see this wildly exaggerated threat removed from new editions of Gore’s “An Inconvenient Truth” anytime soon.

Return to Criticisms of Al Gore’s “An Inconvenient Truth”


Climate change in North Dakota

April 7, 2009
This post is in response to Darin, who left a good comment on my previous post concerning flooding in North Dakota.  Darin said:

Something is going on. I have lived here all my life and experienced two of the record level floods prior to the 1997 flood. That was the flood of 1975 and 1979.

Since then we’ve had 97-2001-2006-2009 that have each bumped all other years in the previous 110 years of record keeping down the list.

Now 7 of the top 10 flood levels come in the last 25 years.

You don’t have to have a masters in statistics to see a correlation to SOMETHING? I don’t know if it is global warming changing weather patterns, but they are changing.

Darin’s observations are legitimate and he has asked some good questions.  I would say that perhaps a master’s in statistics would, in fact, be useful in this situation.  But references to paleoclimatological records would be even more useful.  Why?  Because the real question is whether or not the climate in North Dakota and surrounding areas in the last several decades (while CO2 levels have gone up significantly) has varied in an obvious way from the magnitude of fluctuations seen during the “normal times” over the last several millennia (before CO2 levels rose).   

Consider recent history first. 

Pre-industrial CO2 levels are typically pegged at 280 ppm (parts per million).    Levels rose slowly during the 19th century and reached about 290 ppm by around 1930 and 310 ppm around 1950.   Today the number is at about 385 ppm, as shown below.  So I think that we can agree that the CO2 level started rapidly increasing when the world started becoming highly industrialized in the 40s and 50s. 


So when did the most extreme measured temperatures occur in North Dakota?  Answer: in the 1930s (-60 and +121 degrees F), when CO2 levels were much closer the pre-industrial levels.  When was the previous measured record crest of the Red River?  Answer: 1897, at 40.1 feet, when atmospheric CO2 levels were almost at pre-industrial  levels.

Paleoclimatological history

Drought is the most commonly sited risk of CO2 induced anthropogenic global warming for North Dakota.  For example, the Center for Integrative Environmental Research at the University of Maryland reports in their paper “Economic Impacts of Climate Change on North Dakota”:

“Atmospheric models predict that North Dakota will become drier in the future, with drought patterns becoming more intense as a consequence of global warming.”

Additionally the argument is made that rising levels of atmospheric CO2 will result in “climate change,” as opposed simple “global warming,” with greater extremes in temperature, precipitation, etc.  Using this terminology any changing climate conditions can be attributed to anthropogenic CO2, right?  Well, no.  This argument only works if it can be shown that the range of weather extremes in the era of increasing CO2 is statistically greater than the range of weather extremes during at least several thousand years while CO2 held steady at about 280 ppm.   What does the paleoclimatological record say about North Dakota climate for the last several thousand years?

In 1999, in the Proceedings of the North Dakota Academy of Sciences, Allan Ashworth pointed out that:

North Dakotan’s know only too well the effects of climate change. From 1988 to 1992 the State experienced drought conditions but since then North Dakota has been in a wet cycle. North Dakotans are stoical when it comes to weather but even so there is a concern about what the future will bring. Most of our knowledge of climate change comes from an instrumental record that is only 100 years in length. This record has been extended by dendroclimatology and by high resolution paleontologic and geochemical studies of lake sediments. What these studies are showing is that 100 years is far to short a time to show the variability in the climate record. (emphasis added)

 Ashworth points out some interesting details.  For example, at Rice Lake “maximum drought conditions during the mid-Holocene occurred between 7-6” thousand years ago.  Similarly, “maximum drought conditions at Elk Lake, Itasca Park, Minnesota, occurred between 6.2 to 6” thousand years ago.  At Moon Lake the presence of Iva pollen (which at the present “does not extend north of Nebraska…is thought to represent warmer conditions”  in the mid-Holocene.  Ashworth gives details of lake salinity and level changes during the mid-Holocene and notes “The general assumption is that significant changes in the lake levels are the result of climate change” during the last several thousand years, before CO2 levels rose.  He further notes:

“Individual records show a lot of variation, but there appears to be a cyclicity to drought, with intense droughts occurring on a frequency of 40 – 60 years. What is particularly striking is the Moon Lake salinity record is the magnitude of a series of droughts prior to AD 1200: at AD 200-370, AD 700-850 and AD 1000 -1200. These droughts were all of a greater magnitude than the intense drought of the 1930’s.”

In a 1997 Quaternary Research paper concerning climate variability, as measured by a variety of markers at Moon Lake, North Dakota,  Blas L. Valero-Garces, et al. wrote:

Seismic stratigraphy, sedimentary facies, pollen stratigraphy, diatom-inferred salinity, stable isotope (δ18O and δ13C), and chemical composition (Sr/Ca and Mg/Ca) of authigeniccarbonates from Moon Lake cores provide a congruent Holocene record of effective moisture for the eastern Northern Great Plains. … A change at about 710014C yr B.P. inaugurated the most arid period during the Holocene. Between 7100 and 400014C yr B.P., three arid phases occurred at 6600–620014C yr B.P., 5400–520014C yr B.P., and 4800–460014C yr B.P. Effective moisture generally increased after 400014C yr B.P., but periods of low effective moisture occurred between 2900–280014C yr B.P. and 1200–80014C yr B.P. The data also suggest high climatic variability during the last few centuries.  (emphasis added)

 If Valero-Garces, et. al., are correct then is seems that recent variability in North Dakota is not unusual, and cannot be blamed on anthropogenic CO2.

Sherilyn C. Fritz of the University of Nebraska – Lincoln Department of Geosciences and her co-authors considered the “Hydrologic Variation in the Northern Great Plains During the Last Two Millennia“, and claim that

“The data show that the last 2,000 years have been characterized by frequent shifts between high and low salinity, suggesting shifts between dry and moist periods. Long intervals of high salinity suggest periods of multiple decades when droughts were intense and frequent, thus indicating times when drought was more persistent than in the 20th century. ..[T]he climate of the last 2000 years was hydrologically complex, with large oscillations between low-salinity wet phases and high-salinity dry phases.” (emphasis added)

Fritz gives details from three North Dakota lake sites showing constant variation…

“All records show an interval of prolonged drought between ca. A.D. 40 and 130, followed by a wetter period, and also a dry period about A.D. 250, which two of the records (Moon [Lake]and Rice [Lake]) suggest was sustained for more than a century. Shorter periods of drought are evident at ca. A.D. 400 and 530, and the data suggest a period of major and sustained drought from ca. A.D. 620 to 790. The time from A.D. 1020 to 1150 was also characterized by major drought and was followed by a distinct wet interval to at least A.D. 1300. …. All sites show intervals of very fresh conditions, suggesting high precipitation, sometime between A.D. 1330 and 1430 and in the early decades of the 1800s. The data also suggest periods of drought in the decades surrounding A.D. 1500, 1600, and 1800, and in the latter decades of the 19th century.”

Kathleen Laird of the Department of Ecology at the University of Minnesota writes in Nature  that

“Extreme large-scale droughts in North America, such as the “Dust Bowl” of the 1930s, have been infrequent events within the documented history of the past few hundred years, yet this record may not be representative of long-term patterns of natural variation of drought intensity and frequency. .. Here we present a reconstruction of drought intensity and  frequency over the past 2,300 years in the Northern Great Plains…” (emphasis added)

Laird studied the salinity record of Moon Lake, North Dakota, as an indicator changing hydrological conditions and said…

“Our working assumption is that periods of positive water balance (precipitation > evapotranspiration) are reflected by higher lake levels and lower salinities, whereas when the water balance is negative, lake levels are lower and salinity higher …”

and found the following fluctuating signal:

Figure 2.  Salinity of Moon Lake, North Dakota, from Laird, et. al., Nature

Figure 2. Salinity of Moon Lake, North Dakota, from Laird, et. al., Nature

My conclusion is that the precipitation variation seen over the last 100 years in North Dakota is not unusual when compared to previous centuries, when CO2 levels remained near 280 ppm


Arctic sea ice gone by 2015? A challenge to David Barber.

December 10, 2008
Here we go again. Last March I wrote about the media predictions that the Arctic sea ice would be gone by the summer of 2012. As I showed back then, those wild predictions were based on a simple extrapolation of the minimum summer sea ice extents of 2006 and 2007.


I’ll repeat the basic facts:

The sea ice area in the Arctic has been monitored by satellite for almost 30 years, since 1979. The area of the ice rises and falls, as you would expect, as the year cycles through its seasons. It reaches its yearly minimum by late September or early October. On the average, this minimum has been declining for the last 30 years. After October the northern sea ice area increases until it reaches a maximum in late March or early April each year. The yearly cycle is huge. Typically, about 60% of the total sea ice area melts away as is goes from yearly maximum to the yearly minimum.

The 2007 melt season was very severe and the Arctic sea ice area anomaly reached its lowest level since satellite tracking began.  But that low level was immediately followed by an unprecedented rise in sea ice area in the Arctic in the months following the 2007 summer melt season. The 2008 melt season was quite severe, but not as severe as the 2007 melt season. In order to go from the minimum ice extent of 2007 to zero ice in 2012, the Arctic sea ice extent minimum needs to drop an average of about 600,000 square kilometers per year. But the Arctic ended up with slightly more ice area (about 100,000 square kilometers more) after the 2008 melt season than after the 2007 melt season.  Figure 1, below sums it up.

Figure 1

Figure 1

New predictions of meltdown

Now along comes David Barber  from the University of Manitoba, who estimates that the Arctic Basin will be ice free by the summer of 2015. The Star Phoenix reports:

The ice that has covered the Arctic basin for a million years will be gone in little more than six years because of global warming, a University of Manitoba geoscientist said. And David Barber said that once the sea ice is gone, more humans will be attracted to the Arctic, bringing with them even more ill effects…He said he estimates the Arctic sea should see its first ice-free summer around 2015…Barber has said before the Arctic basin would be free of summer sea ice some time between 2013 and 2030. But their research about recent changes in the Arctic has allowed them to pinpoint the date even closer.

Barber sounds like a smart guy, and was the scientist in charge of a $40-million Arctic research project, the Circumpolar Flaw Lead System Study. He will present his preliminary findings at the International Arctic Change 2008 conference  in Quebec. However, his track record for predictions is rather spotty. Earlier this year National Geographic reported:

“We’re actually projecting this year that the North Pole may be free of ice for the first time [in history],” David Barber, of the University of Manitoba, told National Geographic News aboard the C.C.G.S. Amundsen, a Canadian research icebreaker.”

Prediction for summer of 2008 didn’t work out

The Arctic sea ice concentration reached its minimum around September 15th this year. Figure 2, below, from the Polar Research Group at the University of Illinois, shows the distribution of ice in the Arctic on that day. As you can see, the North Pole was not even close to being ice free. Figure 3 shows the Arctic Basin sea ice area for the last 365 days. Note that in mid-September the the sea ice area anomaly for the Arctic Basin was about negative 0.75 million square kilometers, but there were still 2.5 million square kilometers of ice yet to melt. Again, not even close to zero.

Figure 2

 Figure 2. Arctic Sea Ice Concentration on September 15th, 2008, when the Arctic sea ice reached its minimum for the year. Image from the University of Illinois Polar Research Group.

Figure 3. Figure 3. Arctic Basin sea ice area for the last 365 days.  In mid-September the sea ice anomaly was negative 0.75 million square kilometers, but there were 2.5 million square kilometers more than zero.  Image from the University of Illinois Polar Research Group.  Click on image to see clearer version. 

Those who like to parse words will note that National Geographic piece did not quote Barber as saying the “Arctic Basin” or the “Arctic Ocean” would be ice free during the summer of 2008.  They will correctly point out that he said “the North Pole.”  My answer to that is “So what.”  The North Pole has certainly seen open water in modern times, as attested to by the following images:
Figure 4.

 Figure 4. Skate (SSN-578), surfaced at the North Pole, 17 March 1959. US Navy photo courtesy of This image is from NavSource Online: Submarine Photo Archive

Figure 5.

 Figure 5. Seadragon (SSN-584), foreground, and her sister Skate (SSN-578) during a rendezvous at the North Pole in August 1962. Note the men on the ice beyond the submarines. USN photo from The American Submarine, by Norman Polmar. This image is from NavSource Online: Submarine Photo Archive


What about Barber’s prediction for 2015?

The December 5th StarPhoenix article mentioned above says that according to Barber, “The ice that has covered the Arctic basin for a million years will be gone in little more than six years because of global warming.”  I wonder if Barber can seriously believe that the Arctic Basin has been continuously ice covered for “a million years.”  There is considerable evidence  that the entire Arctic region was warmer just several thousand years ago than it is now. 

Open water from the northern coast of Greenland to the North Pole likely occurred in the not too distant past.  According to Science Daily, Astrid Lysa and colleagues have studied shore features, driftwood samples, microfossils and shore sediments from Northern Greenland. Science Daily reports:

 “The architecture of a sandy shore depends partly on whether wave activity or pack ice has influenced its formation. Beach ridges, which are generally distinct, very long, broad features running parallel to the shoreline, form when there is wave activity and occasional storms. This requires periodically open water,” Astrid Lyså explains.

Pack-ice ridges which form when drift ice is pressed onto the seashore piling up shore sediments that lie in its path, have a completely different character. They are generally shorter, narrower and more irregular in shape.

“The beach ridges which we have had dated to about 6000-7000 years ago were shaped by wave activity,” says Astrid Lyså. They are located at the mouth of Independence Fjord in North Greenland, on an open, flat plain facing directly onto the Arctic Ocean. Today, drift ice forms a continuous cover from the land here.

Astrid Lyså says that such old beach formations require that the sea all the way to the North Pole was periodically ice free for a long time.

“This stands in sharp contrast to the present-day situation where only ridges piled up by pack ice are being formed,” she says.

Funder and Kjaer reported similar results at the 2007 fall meeting of the American Geophysical Union. They point out that “Presently the North Greenland coastline is permanently beleaguered by pack ice…” but “that for a period in the Early Holocene, probably for a millennium or more, the Arctic Ocean was free of sea ice at least for short periods in the summer.” They date this time period to sometime between 8500 and 6000 years ago.  (Update 7/8/10 – Funder now believes “that multiyear sea ice was reduced to between half and a third of the present during the Holocene Thermal Optimum.”  Thanks to Kevin O’Neill and his persistence  in making this correction.)

An Open Challenge to David Barber

I am concerned about climate exaggerations and the effect  they have on public policy makers.  It seems quite clear that David Barber was off the mark when he predicted that “this year that the North Pole may be free of ice for the first time,” because neither the Arctic Ocean, the Arctic Basin nor the North Pole were ice free this past summer.  The North Pole being ice free is not that unusual, and the entire Arctic was probably ice free a relatively short 7,000 years ago.

Now Barber has made the slightly longer term prediction that “The ice that has covered the Arctic basin for a million years will be gone in little more than six years.”  I propose a friendly wager based on this prediction.  I will bet David Barber $1000(US) that the ice covering the Arctic Basin will not be gone anytime before December 31st, 2015.  The bet would involve no transfer of  cash between myself or Barber, but rather, the loser will pay the sum to a charitable organization designated by the winner.

 Definition of terms.  The Arctic Basin is defined by the regional map at Cryosphere Today.  “Gone” means the Arctic Basin sea ice area is less that 100,000 square kilometers, according to National Center for Environmental Prediction/NOAA as presented at Cryosphere Today .  Charitable organizations will be agreed upon at the time the bet is initiated. 

David Barber is a smart guy and evidently an expert in his field.  Taking on a wager with an amateur like me should be like shooting fish in a barrel.  I look forward to reaching an agreement soon.


Don’t Panic – The Arctic has survived warmer temperatures in the past

October 15, 2008

Since we are in the season of comparing charts, graphs and interpretations of the summer Arctic ice melt, it may be useful to pause and consider the history of Arctic temperatures in the Holocene.  There is an abundance of data compiled by hardworking field researchers over the years.  Before everybody got so excited about global warming, it was understood that the Arctic was considerably warmer in earlier parts of the Holocene than in the present.  The evidence for these warmer periods seems to have been forgotten in an age when satellite data causes us to fixate on the last thirty years.

I have collected a short list of papers that indicate times during the mid-Holocene, and places in or near the Arctic, when it was warmer than the present.  Some of these papers may also indicate warmer periods in the early or late Holocene, but I am concentrating primarily on the mid-Holocene in this post.  Figure 1, below, shows the spatial distribution of areas covered by these papers.  Click on the image to get a larger view.  Figure 2 shows the times in the mid-Holocene that each paper says it was warmer than the present.

Figure 1.  Numbers correspond to the journal articles that are listed below.  They also correspond to the numbered lines in figure 2.


 Figure 2.  “Paper #” corresponds to the numbered journal articles listed below.  The colored areas indicate the time periods in the mid-Holocene for which the papers indicate it was warmer than present.


The evidence that the Arctic was warmer in the mid-Holocene than it is now is compelling.  At longitudes almost completely encircling the Arctic, palaeological proxies of all kinds speak from the past with the same message.  Treelines moved in latitudes and elevations.  Alkenone molecules produced from sun loving organisms in the top layer of ocean water recorded the temperature of the water and settled into the depths of the ocean, depositing their temperature record in the sediments.  The pollens of various species of plants changed their ratios with changing temperatures and forest locations, drifted over lakes and settled to the bottom, leaving layer upon layer of temperature history.  Choronomid midges, small insects that live out their short lives in just a few weeks, varied their physiology according to the temperature of their environment, and carried their temperature stories to lake sediments. Forest plant species came and went at temperatures rose and fell, leaving behind their seeds in successive layers of soil as positive reminders that they had been there.

These proxies, and others, strongly indicate that the arctic region was warmer around 5,000 years ago than it is today.  Read the papers listed below to see the details.

Please feel free to criticize my interpretations of the papers, or to point out contradictory or complementary papers.


1. Jung-Hyun Kim, Norel Rimbu, Stephan J. Lorenzb, Gerrit Lohmanna, Seung-IlNam, Stefan Schoutene, Carsten Ruhlemannf, Ralph R. Schneiderg, North Pacific and North Atlantic sea-surface temperature variability during the Holocene, Quaternary Science Reviews, 23, 2004

Kim, et. al., used alkenone-derived sea-surface temperature records from sediments from over 30 locations to derive temperature changes in the Pacific and the Atlantic Oceans during the Holocene.  I have marked the locations of the five highest northern latitude cores, two above the arctic circle and three below it.  Kim’s data for these cores covers only the last 7,000 years, rather than the entire Holocene.  Nevertheless, the cores show temperatures clearly dropping to modern values over the last 7,000 years.  The northern-most core (75N) shows a temperature drop of 4.4 degrees C since 7,000 years ago.  Two other cores show temperature drops greater than 3 degrees C (3.3 and 3.8 degree drops at 57.8N, 8.7E and 57.7N, 7.1E respectively).  The remaining two cores show temperature drops of 1.8 and 0.6 degrees C.  Get copy here.

2. Kultti, S., et. al., Past changes in the Scots pine forest line and climate in Finnish Lapland: a study based on megafossils, lake sediments, and GIS-based vegetation and climate data,” The Holocene, Vol 16 No3, 2004b.

In this paper, Kultti, et. al., (2004b) looked at tree lines in Finnish Lapland and found “Results indicate that pine reached its maximum distribution between 8300 and 4000 cal. yr BP. The inferred minimum shift in mean July temperature was at that time c. +2.5.” Get copy here.

3. Solovieva, N., and Jones, V., A multiproxy record of Holocene environmental changes in the central Kola Peninsula, northwest Russia, Journal of Quaternary Science, 17(4), 2002. 

Solovieva and Jones studied a multi-proxy record of the Kola Peninsula in northern Russia and concluded that for the period from 8000 years ago to 5400 years ago “A maximum of forest cover and the high Pinus abundance during this period indicate the Holocene climate optimum. The multiproxy data from Chuna Lake generally agree with the temperature reconstructions based on the evidence from the Greenland ice-cores (Stuiver et al., 1995) and summer temperatures were likely to have been 2°–3 °C higher than at present.” Get copy here.

4. MacDonald, G., et. al., Radiocarbon dated Pinus sylvestris L. wood from beyond tree-line on the Kola Peninsula, Russia, The Holocene, Vol. 10, No.1, 2000.

MacDonald, et. al., dated Scots Pine wood (Pinus sylvestris L.) in Russia’s Kola Peninsula and found “the density of trees north of the modern tree-line was greatest between 7000 and 5000 BP.  Get copy here.

5. Sarnthein, et. al., Centennial-to-millennial-scale periodicities of Holocene climate and sediment injections off the western Barents shelf, 75°N, Boreas, Vol. 32, 2003.

Sarnthein, et. al., studied sediments on the Barents shelf and found “disappearing sea ice from 6.4–5.2” thousand years before the present, and again “3.0–1.6 kyr BP.” Get copy here.

6. Kultti, S., Oksanen, P., and Väliranta, M., Holocene tree line, permafrost, and climate dynamics in the Nenets Region, East European Arctic, Canadian Journal of Earth Science, Vol 41, 2004a.

 “Pollen, stomata, and macrofossils in a lake core with a basal date of 9700 14C BPwere used to reconstruct past changes in climate and vegetation in the arctic tree line area, northeast European Russia” … “We interpret summer temperatures to have been ca. 3–4 °C higher between ca. 8900 and 5500 BP than at present, and the lowest temperature regime of the Holocene to have occurred between 2700 and 2100 BP.”

7. V.L. Koshkarova and A.D. Koshkarov, RegionalSignatures of Changing Landscape and Climate of Northern Central Siberia in the Holocene, Russian geology and geophysics, N 6, v. 45, 2004

 Koshkarova and Koshkarov(2004) draw their conclusions based on “25 sections of Holocene deposits and soils of northern Central Siberia [that] were studied by paleocarpologicalmethods. Special attention was given to the reconstruction of the dynamics of speciation of forest cover in time and space.” These 25 sections are all above the arctic circle and range in longitude from 86 to 119°E. They divide the Holocene in the region into “intervals 9-8 ka (thermal maximum), 6.5-5ka (climate optimum – combination of higher temperatures and higher humidity), and 2.5-2 ka (thermal minimum).  Get copy here.

8. Robert A. Monserud, Nadja M. Tchebakova, and Olga V. Denissenko, Reconstuction of the mid-Holocene Palaeoclimate of Siberia using a bioclimatic vegetation model, Palaeogeography, Palaeoclimatology, Palaeoecology, 139, 1998

 Monserud, et. al., concentrated on the mid-holocene, which they defined as 4600 to 6000 years before the present. They found that during this period the Siberian winters “between 60 and 65N the palaeoclimate was 5.3 C warmer on average, and between 65 and 70N it was 7.7 C warmer.” For the warmer months the found “Summer was 2-5 C warmer than today between 63 and 73N, embracing much of the Northern Taiga, Forest-Tundra, and Tundra zones. A band of moderate summer temperature anomalies (0 – 2 C) is centered at 65N, and a second band of greater anomalies (2-5 C) is centered at 70N.” Get copy here.

9. Ilyashuk, E.A., Ilyashuk, B.P., Andreev, A.A.b, Bennett, K.D., Hammarlund, D., Hubberten, H.W., Chironomid-inferred Holocene mean July air temperatures for the Lena River Delta area, East Siberia, and the Kola Peninsula, northwestern Russia, ACSYS Final Science Conference,11-14 November 2003, Arctic and Antarctic Research Institute (AARI), St. Petersburg, Russia

 Ilyashuk, et. al. show that Radiocarbon-dated chironomid records from the lake Nikolay region of the Lena River Delta area “imply the warmest (up to 2-3°C warmer than nowadays) climate during ca. 10,200-9200 cal. yr BP…with two short warm oscillations (up to 8.9oC) at c. 5600 and 4500-4100 cal. yr BP…and a relatively long warm period ca. 2300-1400 cal. yr BP.” Get copy here.

10. Matul, A. G., et. al., Recent and Late Holocene Environments on the Southeastern Shelf of the Laptev Sea As Inferred from Microfossil Data, Oceanology, Vol. 47, No. 1, 2007.

Matul, et. al., (2007) from the Russian Academy of Science studied microfossils from the Laptev Sea, which is north of Siberia and well within the Arctic circle. They found that “Judging from the increased diversity and abundance of the benthic foraminifers, the appearance of moderately thermophilic diatom species, and the presence of forest tundra (instead of tundra) pollen, the Medieval warming exceeded the recent “industrial” one and is reflected in the near-delta sediments.” But they indicate that it was warmer even earlier by saying “..the warming in the Laptev Sea during the period of ~5100–6200 years B.P. corresponding to the Holocene climatic optimum could be even more significant as compared with the Medieval Warm Period.”

11. Lawson, D.E.,et. al., 2007, Early to mid-Holocene glacier fluctuations in Glacier Bay, Alaska, in Piatt, J.F., and Gende, S.M., eds., Proceedings of the Fourth Glacier Bay Science Symposium, October 26–28, 2004: U.S. Geological Survey Scientific Investigations Report 2007-5047, p. 54-55.

Lawson looked at glacial advances and retreats in Glacier Bay, Alaska. Glacier Bay is well south of the Arctic circle, but yields information about northern latitude climates. They found a glacial retreat starting 6800 years ago followed by a new glacial advance starting 5000 years ago. The retreat “was long enough to develop a mature forest” on land that was subsequently recovered with ice. Get cop here.

12. Kaufman, D. S., et. al., Holocene thermal maximum in the western Arctic (0-180°W), Quaternary Science Reviews, 23, 2004

In a very comprehensive study of the western Arctic Kaufman and coauthors from the US, UK, Canada, Norway, Iceland, and Russia (2004), studied proxies from over 140 sites in the western hemisphere part of the arctic. Their abstract notes “Paleoclimateinferences based on a wide variety of proxy indicators provide clear evidence for warmer-than-present conditions at 120 of these sites. At the 16 terrestrialsites where quantitative estimates have been obtained, local HTM[Holocene Thermal Maximum] temperatures (primarily summer estimates) were on average 1.6 ± 0.8 ° C higher than present…”
They devided the region into four zones, which I have labeled on the map.
12a. Central Eastern Beringia.Sketchy evidence indicates that the Holocene Therma Maximum occurred very early and had a short duration in this region. Temperatures were several degrees above current temperatures for some period between 12.8 and 7.1 ka. (mean initiation plus one sigma to mean termination minus one sigma).
12b. Northern Continental Canada.Better evidence indicates that this zone experienced higher temperatures from about 7.3 to 4.3 ka.
12c. Canadian Arctic Islands.Good abundant data that this zone was warm from 8.6 to 4.9 ka.
12d. Greenland, Iceland and other Artic islands.Temperatures were high in this zone from 8.6 to 5.2 ka.

13. Stewart, T. and England, J., Holocene Sea-Ice Variations and Paleoenvironmental Change, Northernmost Ellesmere Island, NWT., Canada, Arctic and Alpine Research, Vol 15, No. 1, 1983.

 Stewart and England examined more than 70 samples or Holocene driftwood on Ellesmere at 82° N Latitude. The time distribution of the driftwood indicates “prolonged climatic amelioration at the highest terrestrial latitudes of the northern hemisphere” from 4200 to 6000 years before the present.  Get copy here.

14. D. Dahl-Jensen, K. Mosegaard, N. Gundestrup, G. D. Clow, S. J. Johnsen, A. W. Hansen, N. Balling, Past Temperatures Directly from the Greenland Ice Sheet, Science, 282, 1998

“Dahl-Jensen, et. al., use borehole data to conclude “After the termination of the glacial period, temperatures in our record increase steadily, reaching a period 2.5 K warmer than present during what is referred to as the
Climate Optimum (CO), at 8 to 5 ka. Following the CO, temperatures cool to a minimum of 0.5 K colder than the present at around 2 ka. The record implies that the medieval period around 1000 A.D. was 1 K warmer than present in Greenland.” Get copy here