Rohling et al. (2003) "narrow down" temporal constraints on the millennial-scale variability of climate evident in Greenland ice-core δ¹⁸O records by "determining statistically significant anomalies in the major ion series of the GISP2 ice core," after which they conduct "a process-oriented synthesis of proxy records from the Northern Hemisphere."  In doing so, they find that with respect to temporal relationships among various millennial-scale oscillations in the proxy climate records, a "compelling case" can be made for their being virtually in-phase, based on "the high degree of similarity in event sequences and structures over a very wide spatial domain," plus the fact that their process-oriented synthesis "highlights a consistent common theme of relative dominance shifts between winter-type and summer-type conditions, ranging all the way across the Northern Hemisphere from polar into monsoonal latitudes."  These findings, in their opinion, "corroborate the in-phase relationship between climate variabilities in the high northern latitudes and the tropics suggested in Blunier et al. (1998) and Brook et al. (1999)."  In addition, they report that although individual cycles of the persistent climatic oscillation "appear to have different intensities and durations, a mean periodicity appears around ~1500 years (Mayewske et al., 1997; Van Kreveld et al., 2000; Alley et al., 2001)."  They also report that this cycle, which is clearly not CO2-induced, "seems independent from the global glaciation state (Mayewski et al., 1997; Bond et al., 1999)," and that "¹⁰Be and delta ¹⁴C records may imply a link with solar variability (Mayewski et al., 1997; Bond et al., 2001)."

Dahl-Jensen et al. (1998) used temperature measurements from two Greenland Ice Sheet boreholes to reconstruct the surface temperature history of the ice sheet over the past 50,000 years.  The data revealed that temperatures there during the Last Glacial Maximum approximately 25,000 years ago were 23 ± 2 °C colder than at present.  After the termination of the glacial period, however, they rose to a maximum of 2.5°C warmer than at present, during the Holocene Climatic Optimum of 4,000 to 7,000 years ago.  The Medieval Warm Period and the Little Ice Age were also documented in the record, with temperatures 1°C warmer and 0.5-0.7°C colder than at present, respectively.  Finally, after the end of the Little Ice Age, they report that "temperatures reached a maximum around 1930," but that they "have decreased during the last decades."  All of these observations clash with the hockeystick temperature history of Mann et al. (1998, 1999), which is used by the IPCC to make it appear that the Medieval Warm Period and Little Ice Age were mere fables and that 20th-century warming "during the last decades" was unprecedented over the past one to two millennia and caused by anthropogenic CO2 emissions.

Wagner and Melles (2001) analyzed a sediment core taken from a lake (Raffels So) on an island (Raffles O) situated just off Liverpool Land on the east coast of Greenland for a number of properties related to the past presence of seabirds there, obtaining a 10,000-year record that tells us much about the region's climatic history.  Their data reveal sharp increases in the values of the parameters they measured between about 1100 and 700 years before present, indicative of the summer presence of significant numbers of seabirds during that "medieval warm period," as they describe it, which had been preceded by a several-hundred-year period of little to no seabird presence.  Thereafter, their data suggest another absence of birds during "a subsequent Little Ice Age," which they note was "the coldest period since the early Holocene in East Greenland."  Also evident in their data are signs of a "resettlement of seabirds during the last 100 years, indicated by an increase of organic matter in the lake sediment and confirmed by bird observations."  However, values of the most recent measurements are not as great as those obtained for the Medieval Warm Period, indicating they are in no way unusual.

Seabirds, however, were not the only inhabitants of certain parts of Greenland during the Medieval Warm Period; nor were they the only lifeforms to be forced out during the Little Ice Age.  People were also there during the former period; and they were likewise evicted during the latter.

Working in the vicinity of Igaliku Fjord in South Greenland, Lassen et al. (2004) describe how "the Norse, under Eric the Red, were able to colonize South Greenland at AD 985, according to the Icelandic Sagas, owing to the mild Medieval Warm Period climate with favorable open-ocean conditions."  They also mention, in this regard, that the arrival of the gritty Norsemen was "close to the peak of Medieval warming recorded in the GISP2 ice core which was dated at AD 975 (Stuiver et al., 1995)," while we additionally note that Esper et al. (2002) independently identified the peak warmth of this period throughout North American extratropical latitudes as "occurring around 990."  Hence, it would appear that the window of climatic opportunity provided by the peak warmth of the Medieval Warm Period was indeed a major factor enabling seafaring Scandinavians to establish enduring settlements on the coast of Greenland.

As time progressed, however, the glowing promise of the apex of medieval warmth gave way to the debilitating reality of the depth of Little Ice Age cold.  Jensen et al. (2004), for example, report that the diatom record of Igaliku Fjord "yields evidence of a relatively moist and warm climate at the beginning of settlement, which was crucial for Norse land use," but that "a regime of more extreme climatic fluctuations began soon after AD 1000, and after AD c. 1350 cooling became more severe."  Lassen et al. additionally note that "historical documents on Iceland report the presence of the Norse in South Greenland for the last time in AD 1408," during what they describe as a period of "unprecedented influx of (ice-loaded) East Greenland Current water masses into the innermost parts of Igaliku Fjord."  They also report that "studies of a Canadian high-Arctic ice core and nearby geothermal data (Koerner and Fisher, 1990) correspondingly show a significant temperature lowering at AD 1350-1400," when, in their words, "the Norse society in Greenland was declining and reaching its final stage probably before the end of the fifteenth century."  Consequently, what the relative warmth of the Medieval Warm Period provided the Norse settlers, the relative cold of the Little Ice Age took from them: the ability to survive on Greenland.

Many more details of this incredible saga of five centuries of Nordic survival at the foot of the Greenland Ice Cap have also come to light.  Based on a high-resolution record of Igaliku Fjord 's subsurface water-mass properties derived from analyses of benthic foraminifera, Lassen et al. conclude that stratification of the water column, with Atlantic water masses in its lower reaches, appears to have prevailed throughout the last 3200 years, except for the Medieval Warm Period.  During this unusually mild period, which they describe as occurring between AD 885 and 1235, the outer part of Igaliku Fjord experienced enhanced vertical mixing (which they attribute to increased wind stress) that would have been expected to increase nutrient availability there.  A similar conclusion was reached by Roncaglia and Kuijpers (2004), who found evidence of increased bottom-water ventilation between AD 960 and 1285.  Consequently, based on these findings, plus evidence of the presence of Melonis barleeanus during the Medieval Warm Period (the distribution of which is mainly controlled by the presence of partly decomposed organic matter), Lassen et al. conclude that surface productivity in the fjord during this interval of unusual relative warmth was "high and thus could have provided a good supply of marine food for the Norse people."

Shortly thereafter, however, the cooling that led to the Little Ice Age was accompanied by a gradual re-stratification of the water column, which curtailed nutrient upwelling and reduced the high level of marine productivity that had prevailed throughout the Medieval Warm Period.  These linked events, according to Lassen et al., "contributed to the loss of the Norse settlement in Greenland."  Indeed, with deteriorating growing conditions on land and simultaneous reductions in oceanic productivity, the odds were truly stacked against the Nordic colonies, and it was only a matter of time before their fate was sealed.  As Lassen et al. describe it, "around AD 1450, the climate further deteriorated with further increasing stratification of the water-column associated with stronger advection of (ice-loaded) East Greenland Current water masses."  This development, in their words, led to an even greater "increase of the ice season and a decrease of primary production and marine food supply," which "could also have had a dramatic influence on the local seal population and thus the feeding basis for the Norse population."

The end result of these several conjoined phenomena, in the words of Lassen et al., was that "climatic and hydrographic changes in the area of the Eastern Settlement were significant in the crucial period when the Norse disappeared."  Also, Jensen et al. report that "geomorphological studies in Northeast Greenland have shown evidence of increased winter wind speed, particularly in the period between AD 1420 and 1580 (Christiansen, 1998)," noting that "this climatic deterioration coincides with reports of increased sea-ice conditions that caused difficulties in using the old sailing routes from Iceland westbound and further southward along the east coast of Greenland, forcing sailing on more southerly routes when going to Greenland (Seaver, 1996)."

In summing up these observations, Jensen et al. say that "life conditions certainly became harsher during the 500 years of Norse colonization," and that this severe cooling-induced environmental deterioration "may very likely have hastened the disappearance of the culture."  At the same time, it is also clear that the more favorable living conditions associated with the peak warmth of the Medieval Warm Period -- which occurred between approximately AD 975 (Stuiver et al., 1995) and AD 990 (Esper et al., 2002) -- were what originally enabled the Norse to successfully colonize the region.  Furthermore, in the thousand-plus subsequent years, there has never been a sustained period of comparable warmth, nor of comparable terrestrial or marine productivity, either locally or over the Northern Hemispehre (and likely globally, as well), the strident protestations of Mann et al. (2003) notwithstanding.  Hence, since the peak warmth of the Medieval Warm Period was caused by something quite apart from elevated levels of atmospheric CO2, or any other greenhouse gas for that matter, there is no reason to not believe that a return engagement of that same factor or group of factors may be responsible for the even lesser warmth of today.

Moving to a consideration of more modern times, Chylek et al. (2004) analyzed the temperature histories of three coastal stations in southern and central Greenland that have almost uninterrupted temperature records between 1950 and 2000.  In doing so, they discovered that "summer temperatures, which are most relevant to Greenland ice sheet melting rates, do not show any persistent increase during the last fifty years."  In fact, working with the two stations with the longest records (both over a century in length), they determined that coastal Greenland's peak temperatures occurred between 1930 and 1940, and that the subsequent decrease in temperature was so substantial and sustained that current coastal temperatures "are about 1°C below their 1940 values."  Furthermore, they note that "at the summit of the Greenland ice sheet the summer average temperature has decreased at the rate of 2.2°C per decade since the beginning of the measurements in 1987."  Hence, it would appear that Southern Greenland has not experienced any net warming over the most dramatic period of atmospheric CO2 increase on record.  In fact, it has cooled during this period, and cooled significantly, in a place where CO2-induced warming is supposed to be greatest and most evident, and during a period of time when it is claimed that the earth experienced unprecedented warming.

At the start of the 20th century, however, Greenland was warming, as it emerged, along with the rest of the world, from the depths of the Little Ice Age.  What is more, between 1920 and 1930, when the air's CO2 concentration rose by a mere 3 to 4 ppm, there was a phenomenal warming at all five coastal locations for which contemporary temperature records are available.  In fact, in the words of Chylek et al., "average annual temperature rose between 2 and 4°C [and by as much as 6°C in the winter] in less than ten years."  And this warming, as they note, "is also seen in the ¹⁸O/¹⁶O record of the Summit ice core (Steig et al., 1994; Stuiver et al., 1995)." Commenting on this dramatic temperature rise, which they call the great Greenland warming of the 1920s, Chylek et al. conclude that "since there was no significant increase in the atmospheric greenhouse gas concentration during that time, the Greenland warming of the 1920s demonstrates that a large and rapid temperature increase can occur over Greenland, and perhaps in other regions of the Arctic, due to internal climate variability ... without a significant anthropogenic influence."

Working in West Greenland, Taurisano et al. (2004) found much the same thing that Chylek et al. did in Southern and Central Greenland, as their analyses of all pertinent regional data led them to conclude that "at all stations in the Nuuk Fjord, both the annual mean and the average temperature of the three summer months (June, July and August) exhibit a pattern in agreement with the trends observed at other stations in south and west Greenland (Humlum 1999; Hanna and Cappelen, 2003)."  As they describe it, the temperature data "show that a warming trend occurred in the Nuuk fjord during the first 50 years of the 1900s, followed by a cooling over the second part of the century, when the average annual temperatures decreased by approximately 1.5°C."  Coincident with this cooling trend there was also what they describe as "a remarkable increase in the number of snowfall days (+59 days)."  What is more, they report that "not only did the cooling affect the winter months, as suggested by Hannna and Cappelen (2002), but also the summer mean," noting that "the summer cooling is rather important information for glaciological studies, due to the ablation-temperature relations."  In discussing these observations, Taurisano et al. remark that the temperature data they studied "reveal a pattern which is common to most other stations in Greenland."  Hence, we can be thankful that the part of the Northern Hemisphere that holds the lion's share of its ice has been cooling for the past half-century, and at a very significant rate, making it ever more unlikely that its horde of frozen water will be released to the world's oceans to raise havoc with global sea level any time soon.  Moreover, because the annual number of snowfall days over much of Greenland has increased so dramatically over the same time period, it is possible that enhanced accumulation of snow on its huge ice sheet may be compensating for the melting of many of the world's mountain glaciers and keeping global sea level in check.

In the study of Hanna and Cappelen (2003) cited above by Taurisano et al., an analysis was made of the air temperature history of coastal southern Greenland from 1958-2001 based on data from eight Danish Meteorological Institute stations, as well as the concomitant sea surface temperature (SST) history of the Labrador Sea off southwest Greenland, based on three previously published and subsequently extended SST data sets (Parker et al., 1995; Rayner et al., 1996; Kalnay et al., 1996).  The air temperature data showed a cooling of 1.29°C over the period of study, while two of the three SST databases depicted a cooling of 0.44°C and other one a cooling of 0.80°C.  Both the land air temperature and sea surface temperature series followed similar patterns and were strongly correlated, but with no obvious lead/lag either way.  Also, it was determined that the cooling was "significantly inversely correlated with an increased phase of the North Atlantic Oscillation (NAO) over the past few decades."  Hanna and Cappelen say that the "NAO-temperature link doesn't explain what caused the observed cooling in coastal southern Greenland," but that "it does lend it credibility."  In referring to what they call "this important regional exception to recent 'global warming'," Hanna and Cappelen note that the "recent cooling may have significantly added to the mass balance of at least the southern half of the [Greenland] Ice Sheet."  Consequently, since this part of the ice sheet is the portion that would likely be the first to experience melting in a warming world, it would appear that whatever caused the cooling has not only protected the Greenland Ice Sheet against warming-induced disintegration, it has fortified it against that possibility.

Comiso et al. (2001) studied the Odden ice tongue, a winter ice cover phenomenon that occurs in the Greenland Sea with a length of about 1300 km and an aerial coverage of as much as 330,000 square kilometers.  In doing so, they utilized satellite imagery to analyze and quantify a number of attributes of the ice tongue over the period 1979-1998.  In addition, they used surface air temperature data from nearby Jan Mayen Island to infer the behavior of the phenomenon over the past 75 years.  This exercise revealed that the Odden ice tongue had varied in size, shape and length over the 20-year observation period, but had exhibited no statistically significant change in any of the parameters studied.  However, the proxy reconstruction of Odden ice tongue properties over the past 75 years revealed it to have been "a relatively smaller feature several decades ago," due to the warmer temperatures that prevailed at that time, in harmony with the observational evidence from Jan Mayen Island that temperatures there had cooled at a rate of 0.15 ± 0.03°C per decade during the past 75 years.

Last of all, based on a study of climate data and remotely sensed sea ice concentrations, Laidre and Heide-Jorgensen (2005) report that "since 1970, the climate in West Greenland has cooled, reflected in both oceanographic and biological conditions," with the result that "Baffin Bay and Davis Strait display strong significant increasing trends in ice concentrations and extent, as high as 7.5% per decade between 1979 and 1996, with comparable increases detected back to 1953 (Parkinson et al., 1999; Deser et al., 2000; Parkinson, 2000a,b; Parkinson and Cavalieri, 2002; Stern and Heide-Jorgensen, 2003)."  These trends, in their words, have led to increasing numbers of ice entrapment events, "where hundreds of narwhals [have] died during rapid sea ice formation caused by sudden cold periods (Siegastad and Heide-Jorgensen, 1994; Heide-Jorgensen et al., 2002)."

In conclusion, Greenland, like most of the rest of the world, is subject to a likely solar-induced millennial-scale oscillation of climate that produced a Medieval Warm Period there about a thousand years ago that was approximately 1°C warmer than what it is today; and in contrast to climate-alarmist claims, it has not experienced unprecedented warming over the past few decades.  Rather, it has experienced cooling in most places.  As a result, Greenland is anything but a shining example of what anthropogenic CO2 emissions might do to earth's climate.  In fact, it's a good example of what they likely will not do, i.e., prevent cooling when some other more powerful factor nudges earth's climate in the opposite direction.

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