Global cooling

Date: 98-02-03 

From the Jan. 26, 1998 issue of The New Federalist newspaper...

New Ice Age: Interviewing Geologist

Jack Sauers, Part 1


by Elijah C. Boyd

What edible grains will cold weather support?

How do you ensure the survival of cattle on the range, amidst deep snow drifts? If these problems are not met, how many people, will starve to death as the climate becomes colder?

These common sense questions are not usually taken up in the discussions of alleged global warming-climate change, by the little guru-groupies who are presented to the public as "Knowledgeable Climate Experts," but Washington State geologist Jack Sauers has not only investigated these questions, he is actively working with grain researchers and government officials to supply new, cold-resistant rye grain, as one means to help produce food as the world moves into a new ice age.

The beauty of Sauers's approach revolves around looking for the why of observed physical phenomena, thus allowing him to unify in the mind, the increase in ice mass of glaciers at both poles, the southward descent of boreal vegetation and animals, and the apparently unconnected phenomena of increased volcanic eruptions and El Nino events, as parts of a single astronomical-geologic process.

Sauers authored a Research Communication on the coming ice age in the Winter 1997-98 issue of 21st Century Science & Technology magazine. I spoke to him recently, and asked him to elaborate on his research.

Q: What evidence do you have of the Earth entering a new ice age?

A: I have indeed been working on more information, and I have more hard temperature data coming from many places in the world [and] the activity of glaciers that are growing in many different places, such as Greenland, Norway, and Sweden.

The Bering Glacier, the largest maritime glacier in Alaska, has advanced even more than I documented previously. It has gone down the valley 9 kilometers in the last 17 months, putting icebergs down the river that goes into Prince William Sound. The U.S. Geological Survey (USGS) has had to keep their eye on that because of all the oil tankers that come down there. The last data I have are for 1995. This is a rapidly growing glacier that covers 1,000 square miles and accumulates a lot, and now it is funnelling this accumulation down towards the ocean.

There are now USGS professional papers, which are satellite atlases of the principal glacial areas of the world.

Q- Are they on the web somewhere?

A: The world glacier monitoring service is on the web. I have some copies of graphs from this coming to me, of many different glaciers which are surging, in many places in the world. But a lot of data about different glaciers are not on the web. Dr. Anker Wedek of the Geological Service of Denmark and Greenland, working with the USGS, has put together an atlas on Greenland, of which I just received a copy. It was done in 1995, and it reports on the large number of glaciers which are surging and increasing in volume in Greenland. The same thing is happening in Antarctica, with an even bigger glacier...

Q: Is that the one that is adding 200 gigatons of ice per year?

A: Yes, that was the estimate, done separately by different people. Professor Bentley, who did that work in Antarctica, was the principal author. His summary appeared in a 1993 issue of [the American Geophysical Union's magazine] Eos, along with some other rather complete papers.

They said that that glacier in Antarctica is indeed increasing at 200 gigatons a year. It is also increasing in elevation at about 4 feet a year.

This was measured by looking at some big ITT transmission towers, which are now way down in a hole (!). And, as the glacier adds about 4 feet of ice per year it doesn't stand still-it starts moving out. Therefore, although it's adding 4 feet a year of ice, it's only increasing in elevation at about, actually, two-tenths of a meter a year, because of the mass outflowage.

Q: What are some of the other indications of a looming ice age?

A: In a recent 21st Century article, I noted that the Quasi-Biennial Polar Oscillation Cycle had expanded to the East Coast of the United States, which would mean big storms of an expanding polar-vortex down the Eastern Seaboard. It happened! People in Maine and southern Ontario now think that they are in a little ice age, literally.

Temperatures are dropping. We are now back down to temperatures of below those of the 1890s, according to the National Weather Service....

I took the data from the Weather Service here in Seattle, and you can see that temperatures here have fallen since 1940.

Q: Well, what are the consequences if the temperature is falling?

A: There are many plants and animals that will no longer be able to survive in the northern most areas. There was a paper published in Nature in 1993, which analyzed the pollen in southern Ontario, south of Lake Nipigon, in the last 650 years. The forest there used to be a temperate forest, beech and maples. The maples died out and gave way to oaks, then the oaks died out, and gave way to white pines. Now the white pines are disappearing and being displaced southward, and all that's coming back is boreal forest, not a temperate forest. The boreal forest is of birches and aspen. Those are characteristic of what grows way up north in Scandinavia.

So, in the last 650 years, southern Ontario has gone into the boreal plant zone. For them, the Holocene [the most recent geological epoch] is over! They can probably expect some global warming in about 100,000 years, after the ice melts that's going to cover Canada. This is the meaning of this good pollinology study.

Now, such a change happened before, in southeastern France, in the last interglacial period, the Eemian, 115,000 years ago. This was also published in Nature, by Voillard. They had a temperate forest of hardwoods. Then, in the space of about 20 years-that's a pretty short time-frame-a rapid cooling took place that killed off the temperate forests. All the hardwoods died, and all that was left was boreal forest, the pine, birch, and spruce.

The boreal plant zone, which is today about at the level of Helsinki, Finland, was displaced southward to the Vosges Mountains, in France, From 60 degrees north latitude, to 47 degrees north latitude, This happened in 20 years! Now, that would be like taking the current boreal plant zone on the north side of Lake Superior, and displacing it south to Georgia, in 20 years.

That's going to happen. It'll be just like the area moved to Scandinavia.



Moving like conveyor belt, the current transporting warm, surface water toward the Poles and cold, deep waters toward the Equator. In the Atlantic Ocean, these warm surface water push northward, releasing heat into the atmosphere and becoming cooler and denser. As they do, the water sink and flow southward in the deep ocean. -Note that excessive amounts of freshwater dumping into the North Atlantic WILL alter seawater density and, in time, are affecting the flow of the North Atlantic ocean current. (Global warming has boosted freshwater runoff in the form of glacier meltwater and additional precipitation) Just how much extra freshwater it will alternative the circulation system, known as the Atlantic Meridional Overturning Circulation.. But freshwater runoff into the North Atlantic has been rapidly increasing in recent decades, and runoff is expected to increase further as global temperatures climb higher but check this out, IT'S GOING TO BE FASTER THAN YOU THINK AND  SCIENTISTS THINK - MY WORD TO YOU - THEY ARE WRONG! Check this out--- For the circulation pattern to be seriously affecting by the increasing in freshwater runoff,  the amount of freshwater require to alternative or halt the North Atlantic ocean current. Although of course very unlikely that the freshening freshwater inflowing will be easily continue at the UNEXPECTED RAPID PACE!!!! Water bodies found between Iceland, Greenland, and Norway represents the GREATEST source of freshwater, that are having an impact on the conveyor belt. The more injecting, the more larger amounts of freshwater into the Nordic seas at the precise region that is VERY critical to the conveyor belt. The more excess freshwater runoff from the Arctic will alternative the North Atlantic conveyor belt SOONER in this century than you think and the scientists think. There is a 85 to 95 percent chance that the current will break down sooner. The freshening of the North Atlantic current make its water less dense and so they can't sink down to the depths at which they normally then be transporting back through south---in the results of the circulation stalls, with warmer water no longer being drawn north. When current does stop, it WILL have devastating effects on northern lands, freezing conditions will affect everything!  HOW SOON????  SOONER THAN WE THINK
 Written and Edited by: Jason R. Harlow  Of  Virginia, USA


New Scientist Article: Faltering Currents May Trigger New Ice Age
Posted by mrmeangenes on Thursday December 8, 2005

New Scientist is one of the foremost promoters of the global warming hypothesis-and, in this same issue,has two somber articles devoted to same.

(In the previous issue, a researcher had the bad taste to point out that orbital oscillation of the planet had more to do with global warming than anything else: which he (hastily) added makes man-made global warming that more serious.)

Now comes yet another researcher to show Europe may be on the brink of a "mini-ice age" -totally unrelated to global warming.

Oh,dear ! What shall we do ? What shall we ever do ?

The Sunday  May 08, 2005
Britain faces big chill as ocean current slows
Jonathan Leake, Science Editor

Scientists have detected the first signs of a slowdown in the Gulf Stream — the mighty ocean current that keeps Britain and Europe from freezing.

They have found that one of the “engines” driving the Gulf Stream — the sinking of supercooled water in the Greenland Sea — has weakened to less than a quarter of its former strength. The weakening, apparently caused by global warming, could herald big changes in the current over the next few years or decades. Paradoxically, it could lead to Britain and northwestern and Europe undergoing a sharp drop in temperatures.

Such a change has long been predicted by scientists but the new research is among the first to show clear experimental evidence of the phenomenon.

Peter Wadhams, professor of ocean physics at Cambridge University, hitched rides under the Arctic ice cap in Royal Navy submarines and used ships to take measurements across the Greenland Sea.

“Until recently we would find giant ‘chimneys’ in the sea where columns of cold, dense water were sinking from the surface to the seabed 3,000 metres below, but now they have almost disappeared,” he said.

“As the water sank it was replaced by warm water flowing in from the south, which kept the circulation going. If that mechanism is slowing, it will mean less heat reaching Europe.”

Such a change could have a severe impact on Britain, which lies on the same latitude as Siberia and ought to be much colder. The Gulf Stream transports 27,000 times more heat to British shores than all the nation’s power supplies could provide, warming Britain by 5-8C.

Wadhams and his colleagues believe, however, that just such changes could be well under way. They predict that the slowing of the Gulf Stream is likely to be accompanied by other effects, such as the complete summer melting of the Arctic ice cap by as early as 2020 and almost certainly by 2080. This would spell disaster for Arctic wildlife such as the polar bear, which could face extinction.

Wadhams’s submarine journeys took him under the North Polar ice cap, using sonar to survey the ice from underneath. He has measured how the ice has become 46% thinner over the past 20 years. The results from these surveys prompted him to focus on a feature called the Odden ice shelf, which should grow out into the Greenland Sea every winter and recede in summer.

The growth of this shelf should trigger the annual formation of the sinking water columns. As sea water freezes to form the shelf, the ice crystals expel their salt into the surrounding water, making it heavier than the water below.

However, the Odden ice shelf has stopped forming. It last appeared in full in 1997. “In the past we could see nine to 12 giant columns forming under the shelf each year. In our latest cruise, we found only two and they were so weak that the sinking water could not reach the seabed,” said Wadhams, who disclosed the findings at a meeting of the European Geosciences Union in Vienna.

The exact effect of such changes is hard to predict because currents and weather systems take years to respond and because there are two other areas around the north Atlantic where water sinks, helping to maintain circulation. Less is known about how climate change is affecting these.

However, Wadhams suggests the effect could be dramatic. “One of the frightening things in the film The Day After Tomorrow showed how the circulation in the Atlantic Ocean is upset because the sinking of cold water in the north Atlantic suddenly stops,” he said.

“The sinking is stopping, albeit much more slowly than in the film — over years rather than a few days. If it continues, the effect will be to cool the climate of northern Europe.”

One possibility is that Europe will freeze; another is that the slowing of the Gulf Stream may keep Europe cool as global warming heats the rest of the world — but with more extremes of weather.

The new ice age

The Detroit News 

Little Ice Age (Regional - Europe: Northern) -- Summary
What do studies of the Little Ice Age in Northern Europe reveal about the periods of considerably greater warmth that immediately preceded and followed it?  In this summary we review the findings of several research projects that have provided answers to this important question.

Caseldine (1985) used lichenometry to determine the dates of occurrence of the maximum Little Ice Age extensions of four glaciers in Northern Iceland, as well as their subsequent movements.  This work revealed that their maximum extensions were reached in 1868, 1885, 1898 and 1917.  Since those times, two of the glaciers continued to retreat through the end of the study period (mid-1980s).  The other two, however, slowed, stopped and periodically re-advanced.  In fact, one of them advanced 50 meters between 1977 and 1979, 30 more meters between 1979 and 1981, and 25 additional meters between 1981 and 1983.  Caseldine notes that these advances occurred when mean summer temperature dropped below about 8-8.5°C, which occurred several times over the preceding decades, following the significant downward trend in summer temperature that succeeded the broad maximum experienced in the 1930s and 40s.  These observations thus suggest that by the mid-1980s Iceland's climate may not have fully evolved into what may be called the Modern Warm Period, and that remnants of the Little Ice Age may yet be lurking about the fringes of this North Atlantic island.

Andren et al. (2000) conducted an extensive analysis of temporal compositional changes in siliceous microfossil assemblages and chemical characteristics of various materials found in a well-dated sediment core obtained from the Bornholm Basin in the southwestern Baltic Sea.  Their data revealed the existence of an interval of high primary production at approximately AD 1050.  Diatoms of the period were warm water species such as Pseudosolenia calcar-avis, which they describe as "a common tropical and subtropical marine planktonic species" that "cannot be found in the present Baltic Sea."  They also note that what they call the Recent Baltic Sea Stage, which begins at about AD 1200, starts "at a point where there is a major decrease in warm water taxa in the diatom assemblage and an increase in cold water taxa, indicating a shift towards a colder climate," which they associate with the Little Ice Age.  These data clearly indicate there was a period of time in the early part of the past millennium when the climate of the southwestern Baltic Sea was significantly warmer than it is today.  This period of higher temperatures, according to Andren et al., falls within "a period of early Medieval warmth dated to AD 1000-1100," which "corresponds to the time when the Vikings succeeded in colonizing Iceland and Greenland."

A similar course of climatic events was found by Brooks and Birks (2001), who studied midges, the larval-stage head capsules of which are well preserved in lake sediments and are, according to them, "widely recognized as powerful biological proxies for inferring past climatic change."  Their work revealed that reconstructed temperatures for Lochan Uaine in the Cairngorms region of the Scottish Highlands peaked at about 11°C during what they refer to as the "Little Climatic Optimum," which we typically call the Medieval Warm Period, "before cooling by about 1.5°C which may coincide with the 'Little Ice Age'."  These results, in their words, "are in good agreement with a chironomid stratigraphy from Finse, western Norway (Velle, 1998)," where summer temperatures were "about 0.4°C warmer than the present day" during the Medieval Warm Period.  This latter observation also appears to hold for the Scottish Highlands, since the upper sample of the Lochane Uaine core, which was collected in 1993, "reconstructs the modern temperature at about 10.5°C" which is 0.5°C less than the 11°C value they obtained from the Medieval Warm Period.

In a slightly different type of study that focused on moisture, Nesje et al. (2001) analyzed a 572-cm-long sediment core retrieved from Lake Atnsjoen in southern Norway in an effort to determine the frequency and magnitude of pre-historic floods in that region over the past 4500 years.  Analysis of the more recent portion of the record revealed, as they describe it, "a period of little flood activity around the Medieval period (AD 1000-1400)," which was associated with reduced regional glacier activity, as well as "a period of the most extensive flood activity in the Atnsjoen catchment," which resulted from the "post-Medieval climate deterioration characterized by lower air temperature, thicker and more long-lasting snow cover, and more frequent storms associated with the 'Little Ice Age'."

McDermott et al. (2001) derived a δ18O record - with a time resolution they say is "approximately an order of magnitude better than in the North Atlantic cores that record evidence for quasi-periodic (1475 ± 500 year) ice rafting during the Holocene" - from a stalagmite discovered in Crag Cave in southwestern Ireland, after which they compared this record with the δ18O records from the GRIP and GISP2 ice cores from Greenland.  This work, in their words, provided evidence for "centennial-scale δ18O variations that correlate with subtle δ18O changes in the Greenland ice cores, indicating regionally coherent variability in the early Holocene."  They additionally note that the Crag Cave data "exhibit variations that are broadly consistent with a Medieval Warm Period at ~1000 ± 200 years ago and a two-stage Little Ice Age, as reconstructed by inverse modeling of temperature profiles in the Greenland Ice Sheet."  Also evident in the Crag Cave data were the δ18O signatures of the earlier Roman Warm Period and Dark Ages Cold Period that comprised the prior such cycle of climate in that region.  As for the significance of their findings, McDermott et al. state that the coherent δ18O variations on both sides of the Atlantic "indicate that many of the subtle multi-century δ18O variations in the Greenland ice cores reflect regional North Atlantic margin climate signals rather than local effects."  And, of course, their data confirm the reality of the Medieval Warm Period / Little Ice Age cycle (which climate alarmists refuse to acknowledge), as well as the even-more-strongly-expressed Roman Warm Period / Dark Ages Cold Period cycle that preceded it, once again demonstrating there is nothing unusual or unprecedented about the global warming of the past century or so.

Andersson et al. (2003) inferred surface conditions of the eastern Norwegian Sea (Voring Plateau) from planktic stable isotopes and planktic foraminiferal assemblage concentrations in two seabed sediment cores that covered the last three thousand years.  The climate history derived from their study is remarkably similar to that derived by McDermott et al. for southwestern Ireland.  At the beginning of the 3000-year-long Voring Plateau record, for example, both regions were clearly in the end-stage of the long cold period that preceded the Roman Warm Period.  Hence, both records depict warming from that point in time to the peak of the Roman Warm Period, which occurred about 2000 years BP.  Then, both regions begin their descent into the Dark Ages Cold Period, which held sway until the increase in temperature that produced the Medieval Warm Period, which in both records prevailed from about 800 to 550 years BP.  Last of all, the Little Ice Age is evident, with cold periods centered at approximately 400 and 100 years BP, again in both records.  Of particular interest is the fact that neither record indicates the existence of what has come to be called the Modern Warm Period, and that Andersson et al. report that "surface ocean conditions warmer than present were common during the past 3000 years."

Also working with a marine sediment core, this one retrieved from the southern Norwegian continental margin, Berstad et al. (2003) established its chronology over the past 600 years by means of 210Pb measurements and 14C dates, while they reconstructed spring and summer sea surface temperatures from δ18O data derived from remains of different planktonic foraminifera species.  The results of their analyses suggest, in their words, that "summer water temperatures in the Norwegian Current were 1-2°C colder than at present most of the time between ca. AD 1400 and 1920."  They also say their data suggest that "the spring water temperature along the southern Norwegian continental margin was 1-3°C colder than at present most of the time between AD 1400 and 1700."  In addition, they note that "the cold interval between ca. AD 1400 and 1700/1920 is coincident to the Little Ice Age (LIA)," and within this interval they report that the two coldest periods were coincident with "the solar minima of 'Maunder' and 'Sporer'."

In discussing the implications of their findings for the thermohaline circulation of the ocean and its role in facilitating global climate change, Berstad et al. forthrightly express their opinion that the Little Ice Age was of global extent, which is something that is vociferously denied by climate alarmists.  Berstad et al. note, for example, that "the evidence of the Little Ice Age as a global event, as documented in changes in the atmospheric circulation in the Southern (Kreutz et al., 1997) and Northern Hemisphere (O'Brian et al., 1995), suggests that large-scale changes in ocean and atmospheric circulation were involved," additionally stating that "the findings of increased deep-water formation in the Southern Ocean during the Little Ice Age by Broecker (1999, 2001) and Broecker et al. (1999) further support this interpretation of variability in the thermohaline circulation.  In summation, Berstad et al. suggest that the Little Ice Age was (1) real, (2) really cold, and (3) solar-induced, while they report corroborating evidence for its global extent.

Continuing towards the present, Casely and Dugmore (2004) studied fluctuations of two key outlet glaciers of the Myrdalsjokull ice cap in Iceland (Tungnakvislajokull and Krossarjokull), employing "geomorphic mapping and geochronology based on a combination of historical sources, lichenometry and tephrochronology."  As they describe it, this work revealed "there is geomorphological and tephrochronological evidence for a 'Little Ice Age' maximum Holocene advance of Krossarjokull and Tungnakvislajokull, which probably culminated in two advance phases during the early and mid-19th century."  They also note "there is no evidence of Neoglacial advances of a greater extent," and to drive this point home, they report that, "as elsewhere in the North Atlantic, the Little Ice Age advances at these southwest outlets of Myrdalsjokull are the most extensive during Neoglaciation."  Consequently, it can be appreciated that after reaching what was likely the coldest part of the current interglacial, i.e., the Little Ice Age, it is little wonder the planet would have to warm significantly to return to relative interglacial "normalcy," i.e., temperatures characteristic of the Medieval and Roman Warm Periods; yet climate alarmists continue to rant and rave about what was only to be expected, i.e., that temperatures would rise significantly at the end of the Little Ice Age after having fallen significantly during its development.

Contemporaneously, Roncaglia (2004) analyzed variations in organic matter deposition from approximately 6350 cal yr BC to AD 1430 in a sediment core extracted from the Skalafjord, southern Eysturoy, Faroe Islands, finding that an increase in "structured brown phytoclasts, plant tissue and sporomorphs in the sediments dating to ca. AD 830-1090 indicate increased terrestrial influx and inland vegetation supporting the idea of improved climatic conditions."  She also reports that high "total dinoflagellate cyst concentration and increased absolute amount of loricae of tintinnid and planktonic crustacean eggs occurred at ca. AD 830-1090," concluding that these observations "may suggest increased primary productivity in the waters of the fjord (Lewis et al., 1990; Sangiorgi et al., 2002)."

The "amelioration of climate conditions" that promoted the enhanced productivity of both land and sea at this time, in the words of Roncaglia, "may encompass the Medieval Warm Period in the Faroe region," and indeed it does, for the data of Esper et al. (2002) show, in their words, that the warmest portion of the Medieval Warm Period "covers the interval 950-1045, with the peak occurring around 990."  Thereafter, Roncaglia reports an increased concentration of certain organisms at about AD 1090-1260 that she says "suggests a cooling, which may reflect the beginning of the Little Ice Age."  This finding, too, is in harmony with the findings of Esper et al., which show a dramatic drop in temperature over this period.

Utilizing plant macrofossils, testate amoebae and degree of humification as proxies for environmental moisture conditions in yet another approach to climate reconstruction, Blundell and Barber (2005) developed a "wetness history" from a peat core extracted from Tore Hill Moss, a raised bog in the Strathspey region of Scotland, which begins 2800 years ago and extends all the way to AD 2000.  The most clearly defined and longest interval of sustained dryness in this entire history stretches from about AD 850 to AD 1080, coincident with the Medieval Warm Period as defined by both Roncaglia and Esper et al., while the most extreme wetness interval occurred during the depths of the last stage of the Little Ice Age.  In addition, preceding the Medieval Warm Period was a highly chaotic period of generally greater wetness corresponding to the Dark Ages Cold Period, while dryness peaks representing the Roman Warm Period are also evident in the data.  Consequently, in local contradiction of the climate-alarmist claim that the late 20th century was the warmest period experienced by the globe over the past two millennia, the correlation this study demonstrates to exist between relative wetness and warmth in Scotland strongly suggests that the temperature of the late 20th century was nowhere near the highest of the past two millennia in that particular part of the world.  In addition, Blundell and Barber cite many studies that report findings similar to theirs throughout much of the rest of Europe and the North Atlantic Ocean.  Consequently, the regional challenge this group of studies provides to the IPCC-endorsed hockeystick temperature history of Mann et al. (1999) is quite substantial.

A similar challenge is provided by the study of Linderholm and Gunnarson (2005), who worked with a multi-millennial tree-ring width chronology derived from living and subfossil Scots pines sampled close to the present tree-line in the central Scandinavian Mountains.  This proxy temperature record runs from 2893 BC to AD 2002 and contains several periods of anomalously warm and cold summers, including (1) 550 to 450 BC (Roman Warm Period), when summer temperatures were the warmest of the entire record, exceeding the 1961-1990 mean by more than 6°C, (2) AD 300 to 400 (Dark Ages Cold Period), which was "the longest period of consecutive cold summers," averaging 1.5°C less than the 1961-1990 mean, (3) AD 900 to 1000, a warm era corresponding to the Medieval Warm Period, and (4) AD 1550 to 1900, a cold period known as the Little Ice Age.  With respect to the latter portion of the record, which encompasses the period of modern global warming, Linderholm and Gunnarson say that this phenomenon "does not stand out as an anomalous feature" and that "other periods show more rapid warming and also higher summer temperatures."  In fact, the last half of the 20th century in their temperature reconstruction actually exhibits cooling.

Finally, in a study that looked at climate and civilization at one and the same time, Berglund (2003) identified several periods of expansion and decline of human cultures in Northwest Europe and compared them with a history of reconstructed climate "based on insolation, glacier activity, lake and sea levels, bog growth, tree line, and tree growth."  In doing so, he determined there was "a positive correlation between human impact/land-use and climate change."  Specifically, in the latter part of the record, where both cultural and climate changes were best defined, there was, in his words, a great "retreat of agriculture" centered on about AD 500, which led to "reforestation in large areas of central Europe and Scandinavia."  Berglund notes that "this period was one of rapid cooling indicated from tree-ring data (Eronen et al., 1999) as well as sea surface temperatures based on diatom stratigraphy in [the] Norwegian Sea (Jansen and Koc, 2000), which can be correlated with Bond's event 1 in the North Atlantic sediments (Bond et al., 1997)."  Next came what he calls a "boom period" that covered "several centuries from AD 700 to 1100."  This interval of time, according to Berglund, proved to be "a favorable period for agriculture in marginal areas of Northwest Europe, leading into the so-called Medieval Warm Epoch," when "the climate was warm and dry, with high treelines, glacier retreat, and reduced lake catchment erosion."  This period "lasted until around AD 1200, when there was a gradual change to cool/moist climate, the beginning of the Little Ice Age ... with severe consequences for the agrarian society."

In conclusion, many types of data, including those related to human enterprise, bear witness to the reality and significance of the natural, i.e., non-anthropogenic-induced, millennial-scale oscillation of climate that created and sustained the Little Ice Age, as well as the Medieval Warm Period that preceded it and the warming that has followed it, but which has not yet returned the planet to the degree of warmth experienced at the peak of that prior warm node of the recurring climate cycle.

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Last updated 7 December 2005