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GLOBAL WARMING DESTROYS ARCTIC ICE SHELF

Posted on: August 8, 2020

Grise Fiord: Climate Change - Ellesmere Island Ice Shelves ...

Milne Ice shelf, Canada'S Fully Intact Ice Shelf Collapsed

Canada's Milne Ice Shelf Collapses Into Ice Islands | Digital Trends

 

THIS POST IS A CRITICAL REVIEW OF MEDIA REPORTS THAT THE COLLAPSE OF THE MILNE ICE SHELF IS A CATASTROPHIC EVENT AND A  SIGN OF THE COMING DEMISE OF THE ARCTIC BY HUMAN CAUSED GLOBAL WARMING

 

PART-1: EXAMPLE MEDIA REPORT

Canada’s Last Intact Ice Shelf Collapses Due to Warming, By Associated Press, August 07, 2020 09:10 PM. The collapse of the Milne Ice Shelf, the last fully intact ice shelf in Canada, is seen reducing its size by about 43% according to Environment and Climate Change Canada. Satellite images taken July 30 to Aug. 4, 2020 over Ellesmere Island. Much of Canada’s remaining intact ice shelf has broken apart into hulking iceberg islands thanks to a hot summer and global warming, scientists said. Canada’s 4,000-year-old Milne Ice Shelf on the northwestern edge of Ellesmere Island had been the country’s last intact ice shelf until the end of July when ice analyst Adrienne White of the Canadian Ice Service noticed that satellite photos showed that about 43% of it had broken off. She said it happened around July 30 or 31. Two giant icebergs formed along with lots of smaller ones, and they have already started drifting away, White said. The biggest is nearly the size of Manhattan — 21 square miles (55 square kilometers) and 7 miles long (11.5 kilometers). They are 230 to 260 feet (70 to 80 meters) thick. “This is a huge, huge block of ice,” White said. “If one of these is moving toward an oil rig, there’s nothing you can really do aside from move your oil rig.” The 72-square mile (187 square kilometer) undulating white ice shelf of ridges and troughs dotted with blue meltwater had been larger than the District of Columbia but now is down to 41 square miles (106 square kilometers). Temperatures from May to early August in the region have been 9 degrees (5 degrees Celsius) warmer than the 1980 to 2010 average, University of Ottawa glaciology professor Luke Copland said. This is on top of an Arctic that already had been warming much faster than the rest of globe, with this region warming even faster. Without a doubt, it’s climate change,” Copland said, noting the ice shelf is melting from both hotter air above and warmer water below. The Milne was very special,” he added. “It’s an amazingly pretty location. Ice shelves are hundreds to thousands of years old, thicker than long-term sea ice, but not as big and old as glaciers, Copland said. Canada used to have a large continuous ice shelf across the northern coast of Ellesmere Island in the Canadian territory of Nunavut, but it has been breaking apart over the last decades because of man-made global warming, White said. By 2005 it was down to six remaining ice shelves but “the Milne was really the last complete ice shelf,” she said. There aren’t very many ice shelves around the Arctic anymore,” Copland said. “It seems we’ve lost pretty much all of them from northern Greenland and the Russian Arctic. There may be a few in a few protected fjords.

 

 

PART-2: CRITICAL COMMENTARY

  1. What we find in the bibliography below is that though Arctic ice shelves were stable during the last glaciation period, they began disintegrating almost as soon as the Holocene interglacial got started after the Younger Dryas event – and particularly so in the warm periods of the warming and cooling cycles of the Holocene described in a related post. [LINK] .
  2.  Some stabilization of the ice shelves are seen in the cool periods of the Holocene identified by Mayewski (2004) as six cold events dated 9000″8000, 6000-5000YBP, 4200-3800YBP, 3500-2500YBP, 1200-1000YBP, and 600-150YBP; but with widespread instability and ice shelf destruction in the intervening warm periods identified as the Holocene Climate Optimum, the most notable of these events and also the Bronze Age Warming (BAW) also known as the Minoan Warm Period ≈3000YBP, the Roman Warm Period (RWP) ≈2000YBP, the Medieval Warm Period (MWP) ≈1000YBP, and the current warm period that began at the end of the most recent cold period that ended about 150YBP  and thought to be an artificial creation of the industrial economy  (AGW).
  3. Arctic ice shelves follow a pattern of stability and growth in the cold periods and destruction and decay in the warm periods. In this context, the human caused anthropogenic warming of the current warm period does not appear to be exceptional in its destruction of Arctic ice shelves. If anything, Arctic ice shelves have been relatively stable in the AGW era when compared with their destruction in the other Holocene warm periods listed above.
  4. Based on these findings reported in the bibliography below, we find little evidence for the alarm that anthropogenic global warming has created an unnatural and exceptional human caused destruction of Arctic ice shelves in the current warm period. An alternative view is found in in England (2008), where the authors do not find but predict a more violent sea shelf destruction in the current warm period yet to come. The Milne ice shelf collapse of 2020 reported in the media may be interpreted in terms of the beginning of the ice shelf destruction projected in England (2008). We will know in the next few decades if the relatively mild Arctic ice shelf destruction in the current warm period is about to give way to the kind of ice shelf destruction seen in prior warm periods of the Holocene – as projected by England (2008). 

 

 

 

 

PART-3:  THE RELEVANT BIBLIOGRAPHY

  1. Jeffries, MARTIN O. “Ellesmere Island ice shelves and ice islands.” Satellite image atlas of glaciers of the world: North America (2002): J147-J164bandicam 2020-08-08 18-04-32-443
  2. Antoniades, Dermot, et al. “Holocene dynamics of the Arctic’s largest ice shelf.” Proceedings of the National Academy of Sciences 108.47 (2011): 18899-18904Ice shelves in the Arctic lost more than 90% of their total surface area during the 20th century and are continuing to disintegrate rapidly. The significance of these changes, however, is obscured by the poorly constrained ontogeny (origins and history) of Arctic ice shelves. Here we use the sedimentary record behind the largest remaining ice shelf in the Arctic, the Ward Hunt Ice Shelf (Ellesmere Island, Canada), to establish a long-term context in which to evaluate recent ice-shelf deterioration. Multiproxy analysis of sediment cores revealed pronounced biological and geochemical changes in Disraeli Fiord in response to the formation of the Ward Hunt Ice Shelf and its fluctuations through time. Our results show that the ice shelf was absent during the early Holocene and formed 4,000 years ago in response to climate cooling. Paleoecological data then indicate that the Ward Hunt Ice Shelf remained stable for almost three millennia before a major fracturing event that occurred ∼1,400 years ago. After reformation ∼800 years ago, freshwater was a constant feature of Disraeli Fiord until the catastrophic drainage of its epishelf lake in the early 21st century.
  3. EVANS, DAVID JA. “An early Holocene narwhal tusk from the Canadian High Arctic.” Boreas 18.1 (1989): 43-50.  A narwhal (Monodon monoceros) tusk from 34 m above sea level and located at 82°N on the northwest coast of Ellesmere Island has been radiocarbon dated at 6,830 ± 50 B.P. It was collected from a narrow coastal strip which is isolated from the adjacent Arctic Ocean by glacier ice, ice shelf and multiyear pack ice. The specimen represents an early Holocene range extension of 400–700 km over the present. Because the narwhal requires abundant open water to survive, the Holocene tusk is an important independent item of proxy data on palaeoclimatic change. Contemporary migration routes are directly related to seasonal sea ice in the inter‐island channels of the central Canadian Arctic archipelago. The presence of a narwhal on the northwest Ellesmere Island coast at 6,830 ± 50 B. P. suggests that sea ice and ice‐shelf conditions were more favourable at that time. A comprehensive chronological framework for late Quaternary and Holocene geomorphic/climatic events from northern Ellesmere Island records a warm early Holocene characterized by abundant driftwood entry into the high Arctic. This was followed by a mid‐Holocene climatic deterioration during which the ice shelves of the Ellesmere coast formed. Therefore, the narwhal tusk is further evidence that a period of maximum postglacial warmth occurred during the early Holocene in the Canadian high Arctic.
  4. Evans, David JA, and John England. “Geomorphological evidence of Holocene climatic change from northwest Ellesmere Island, Canadian high arctic.” The Holocene 2.2 (1992): 148-158.  Proxy data from the northern coast of Ellesmere Island are used to reconstruct Holocene palaeoclimate and appear to corroborate the ice core record from the Canadian and Greenland high arctic despite some regional variation. Geomorphological evidence indicates that deglaciation was associated with a marked climatic amelioration in the late Pleistocene/early Holocene (≥10 ka BP). This contrasts with glaciers on the south side of Grant Land Mountains which started to retreat at 7.5 ka BP perhaps due to significant differences in glacioclimatic regime and the influence of the Arctic Ocean. Indicators of sea ice conditions on northern Ellesmere Island suggest that the early Holocene was a period of considerable open water. Radiocarbon dates on driftwood collected from behind the north coast ice shelves suggest that the ice shelves formed during a mid-Holocene climatic deterioration. Geomorphic evidence shows that the ice shelves are presently breaking up and melting in response to recent warming. Glaciers have responded to Holocene climate change at varying rates which are related to drainage basin size. Many large glaciers are still advancing in response to the mid-Holocene climatic deterioration. Some glaciers display evidence of dual advances which may reflect mid-Holocene and ‘Little Ice Age’ accumulation. Other evidence of ‘Little Ice Age’ cold and recent warmth is perennial snowbank retreat and fluvially eroded ice wedge polygons near sea level. Different cryogenic systems on northern Ellesmere Island have responded to Holocene climate change at various rates: 103 a for glaciers with drainage basin areas >5 km2; 102 a for ice shelves and glaciers <5 km2; and 101 a for sea ice.
  5. England, John H., et al. “A millennial‐scale record of Arctic Ocean sea ice variability and the demise of the Ellesmere Island ice shelves.” Geophysical Research Letters 35.19 (2008) Sea‐ice ice shelves, at the apex of North America (>80° N), constitute the oldest sea ice in the Northern Hemisphere. We document the establishment and subsequent stability of the Ward Hunt Ice Shelf, and multiyear landfast sea ice in adjacent fiords, using 69 radiocarbon dates obtained on Holocene driftwood deposited prior to coastal blockage. These dates (47 of which are new) record a hiatus in driftwood deposition beginning ∼5500 cal yr BP, marking the inception of widespread multiyear landfast sea ice across northern Ellesmere Island. This chronology, together with historical observations of ice shelf breakup (∼1950 to present), provides the only millennial‐scale record of Arctic Ocean sea ice variability to which the past three decades of satellite surveillance can be compared. Removal of the remaining ice shelves would be unprecedented in the last 5500 years. This highlights the impact of ongoing 20th and 21st century climate warming that continues to break up the remaining ice shelves and soon may cause historically ice‐filled fiords nearby to open seasonally. [LINK] .

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