By WUWT regular “Just The Facts”
A June 16th article in the Economist “The vanishing north” states that;
“Between now and early September, when the polar pack ice shrivels to its summer minimum, they will pore over the daily sea ice reports of America’s National Snow and Ice Data Centre. Its satellite data will show that the ice has shrunk far below the long-term average. This is no anomaly: since the 1970s the sea ice has retreated by around 12% each decade. Last year the summer minimum was 4.33m square km (1.67m square miles)—almost half the average for the 1960s.
The Arctic’s glaciers, including those of Greenland’s vast ice cap, are retreating. The land is thawing: the area covered by snow in June is roughly a fifth less than in the 1960s. The permafrost is shrinking. Alien plants, birds, fish and animals are creeping north: Atlantic mackerel, haddock and cod are coming up in Arctic nets. Some Arctic species will probably die out.
Perhaps not since the 19th-century clearance of America’s forests has the world seen such a spectacular environmental change. It is a stunning illustration of global warming, the cause of the melt. It also contains grave warnings of its dangers. The world would be mad to ignore them.”
However, the Economist’s assertion that “global warming” is “the cause of the melt” is demonstrably false.
There is ample evidence that the Arctic has warmed over the last several decades, e.g.; the RSS Northern Polar Temperature Lower Troposphere(TLT) Brightness Temperature Anomaly;
shows a .337 K/C per decade increase.
However, atmospheric temperatures are just one of numerous variables that are the “cause of the melt”. In fact, the largest influences on Arctic Sea Ice appear to be wind and Atmospheric Oscillations, i.e.:
In this 2007 NASA article “NASA Examines Arctic Sea Ice Changes Leading to Record Low in 2007“;
“Son V. Nghiem of NASA’s Jet Propulsion Laboratory, said that “the rapid decline in winter perennial ice the past two years was caused by unusual winds. “Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic,” he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.”
“The winds causing this trend in ice reduction were set up by an unusual pattern of atmospheric pressure that began at the beginning of this century,” Nghiem said.”
This 2007 paper “Rapid reduction of Arctic perennial sea ice” by Nghiem, Rigor, Perovich, Clemente-Colo, Weatherly and Neumann, found that;
“Perennial-ice extent loss in March within the DM domain was noticeable after the 1960s, and the loss became more rapid in the 2000s when QSCAT observations were available to verify the model results. QSCAT data also revealed mechanisms contributing to the perennial-ice extent loss: ice compression toward the western Arctic, ice loading into the Transpolar Drift (TD) together with an acceleration of the TD carrying excessive ice out of Fram Strait, and ice export to Baffin Bay.”
This 2010 Guardian article “Wind contributing to Arctic sea ice loss, study finds” states that;
“Much of the record breaking loss of ice in the Arctic ocean in recent years is down to the region’s swirling winds and is not a direct result of global warming, a new study reveals.”
This 2011 paper “Recent wind driven high sea ice export in the Fram Strait contributes to Arctic sea ice decline” by L. H. Smedsrud, et al.;
“used “geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25% larger than during the 1960’s.”
This 2004 Science Daily article, ”Winds, Ice Motion Root Cause Of Decline In Sea Ice, Not Warmer Temperatures” states that,
“extreme changes in the Arctic Oscillation in the early 1990s — and not warmer temperatures of recent years — are largely responsible for declines in how much sea ice covers the Arctic Ocean, with near record lows having been observed during the last three years, University of Washington researchers say.”
“It may have happened more than a decade ago, but the sea ice appears to still “remember” those Arctic Oscillation conditions, according to Ignatius Rigor, a mathematician with the UW’s Applied Physics Laboratory.”
This 2004 paper “Variations in the Age of Arctic Sea-ice and Summer Sea-ice Extent” by Ignatius G. Rigor & John M. Wallace, found that;
“The winter AO-index explains as much as 64% of the variance in summer sea-ice extent in the Eurasian sector, but the winter and summer AO-indices combined explain less than 20% of the variance along the Alaskan coast, where the age of sea-ice explains over 50% of the year-to year variability. If this interpretation is correct, low summer sea-ice extents are likely to persist for at least a few years. However, it is conceivable that, given an extended interval of low-index AO conditions, ice thickness and summertime sea-ice extent could gradually return to the levels characteristic of the 1980′s.”
This 2010 paper, “Influence of winter and summer surface wind anomalies on summer Arctic sea ice extent” by Masayo Ogi, Koji Yamazaki and John M. Wallace, published in Geophysical Research Letters states that;
“We have shown results indicating that wind‐induced, year‐to‐year differences in the rate of flow of ice toward and through Fram Strait play an important role in modulating September SIE on a year‐to‐year basis and that a trend toward an increased wind‐induced rate of flow has contributed to the decline in the areal coverage of Arctic summer sea ice.”
This 2001 paper, “Fram Strait Ice Fluxes and Atmospheric Circulation: 1950–2000” by Torgny Vinje found that:
“Observations reveal a strong correlation between the ice fluxes through the Fram Strait and the cross-strait air pressure difference.”
“Although the 1950s and 1990s stand out as the two decades with maximum flux variability, significant variations seem more to be the rule than the exception over the whole period considered.”
“A noticeable fall in the winter air pressure of 7 hPa is observed in the Fram Strait and the Barents Sea during the last five decades.”
“The corresponding decadal maximum change in the Arctic Ocean ice thickness is of the order of 0.8 m. These temporal wind-induced variations may help explain observed changes in portions of the Arctic Ocean ice cover over the last decades. Due to an increasing rate in the ice drainage through the Fram Strait during the 1990s, this decade is characterized by a state of decreasing ice thickness in the Arctic Ocean.”
This 2003 paper “Arctic climate change: observed and modelled temperature and sea-ice variability“, by By OLA M. JOHANNESSEN, LENNART BENGTSSON, MARTIN W. MILES, SVETLANA I . KUZMINA, VLADIMIR A. SEMENOV, GENRIKH V. ALEKSEEV, ANDREI P. NAGURNYI, VICTOR F. ZAKHAROV, LEONID P. BOBYLEV, LASSE H. PETTERSSON, KLAUS HASSELMANN and HOWARD P. CATTLE states that;
“The decreases in recent decades, which are also partially due to circulation-driven ice export through the Fram Strait between Greenland and Svalbard (Vinje, 2001), have coincided with a positive trend in the NAO, with unusually high index values in the late 1980s and 1990s. During this period, the variability of ice motion and ice export through the Fram Strait was correlated strongly with the NAO; r∼ 0.86 for the ice area flux (Kwok and Rothrock, 1999) and r∼ 0.7 for the ice volume flux (Hilmer and Jung, 2000), although the relationship was insignificant (r∼ 0.1) before the mid 1970s (Hilmer and Jung, 2000). Deser et al. (2000) analysed a 40-yr gridded data set (1958–97) to determine the association between arctic sea ice, SAT and SLP, concluding that the multidecadal trends in the NAO/AO in the past three decades have been ‘imprinted upon the distribution of Arctic sea ice’, with the first principal component of sea-ice concentration significantly correlated (r∼−0.63) with the NAO index, recently cause-and-effect modelled by Hu et al. (2002). None the less, our calculations and those of Deser et al. (2000) indicate that, even in recent decades, only about one third of the variability in arctic total ice extent and MY ice area (Johannessen et al., 1999) is explained by the NAO index,”
This 2002 paper “Response of Sea Ice to the Arctic Oscillation” by IGNATIUS G. RIGOR, JOHN M. WALLACE and ROGER L. COLONY found that
“Hilmer and Jung (2000) note a secular change in the relationship between the Fram Strait ice flux and the NAO; the high correlation noted by Kwok and Rothrock (1999) from 1978 to 1996 was not found in data prior to 1978. We expect our overall results to be more robust given the strong relationship between the AO and SIM over the Arctic, as compared to the weaker relationship between the north–south flow through Fram Strait and the AO. Even if one ignored the effect of the AO on the flux of ice through Fram Strait, the divergence of ice in the eastern Arctic would be still be ;50% greater under high-index conditions than under low-index conditions, and the heat flux would be ;25% greater.”
”We have shown that sea ice provides memory for the Arctic climate system so that changes in SIM driven by the AO during winter can be felt during the ensuing seasons; that is, the AO drives dynamic thinning of the sea ice in the eastern Arctic during winter, allowing more heat to be released from the ocean through the thinner ice during spring, and resulting in lower SIC during summer and the liberation of more heat by the freezing of the ice in autumn. The correlations between the wintertime AO and SIC and SAT during the subsequent seasons offers the hope of some predictability, which may be useful for navigation along the Northern Sea route.”
This 2000 paper, “Arctic decadal and interdecadal variability” by Igor V. Polyakov and Mark A. Johnson, found that;
”The decadal-scale mode associated with the Arctic Oscillation (AO) and a low-frequency oscillation (LFO) with an approximate time scale of 60-80 years, dominate. Both modes were positive in the 1990s, signifying a prolonged phase of anomalously low atmospheric sea level pressure and above normal surface air temperature in the central Arctic. Consistent with an enhanced cyclonic component, the arctic anticyclone was weakened and vorticity of winds became positive. The rapid reduction of arctic ice thickness in the 1990s may be one manifestation of the intense atmosphere and ice cyclonic circulation regime due to the synchronous actions of the AO and LFO. Our results suggest that the decadal AO and multidecadal LFO drive large amplitude natural variability in the Arctic making detection of possible long-term trends induced by greenhouse gas warming most difficult.
“A simultaneous thinning of the sea ice is also speeding up the shrinkage, because thinner ice is more liable to melt. According to Peter Wadhams of Cambridge University, the average thickness of the pack ice has fallen by roughly half since the 1970s, probably for two main reasons. One is a rise in sea temperatures: in the summer of 2007 coastal parts of the Arctic Ocean measured 7°C—bracingly swimmable. The other was a prolonged eastward shift in the early 1990s in the Arctic’s prevailing winds, known as the Arctic Oscillation. This moved a lot of ice from the Beaufort Gyre, a revolving current in the western Arctic, to the ocean’s other main current, the Transpolar Drift Stream, which runs down the side of Siberia. A lot of thick, multi-year ice was flushed into the Atlantic and has not been replaced.”
As such, there is ample evidence that “global warming” is not “the cause of the melt” as the Economist erroneously infers in its article “The vanishing north”. The Economist’s over simplifications, poor reporting and overt alarmism are indicative of the sad state of formerly respected information source.