Archives par mot-clé : Ice

2019 Arctic Ice Demise Deferred Again

by Ron Clutz, October 2, 2019 in ScienceMatters


MASIE daily results for September show 2019 early melting followed by an early stabilizing and refreezing.

Note that 2019 started the month about 800k km2 below the 12 year average (2007 through 2018 inclusive).  There was little additional loss of ice, a rise then a dip below 4 M km2, and a sharp rise ending the month.  Interestingly, 2019 matched the lowest year 2012 at the start, but ended the month well ahead of both 2012 and 2007.

The table for day 273 shows distribution of ice across the regions making up the Arctic ocean.

New Study: Modern Arctic Sea Ice Cover Is Present MONTHS Longer Than Nearly All Of The Last 8000 Years

by Caron et al., 2019, 30 Sep. 2019 in NoTricksZone


A new reconstruction of Arctic (NW Greenland) sea ice cover (Caron et al., 2019) reveals modern day sea ice is present multiple months longer than almost any time in the last 8000 years…and today’s summer sea surface temperatures s are among the coldest of the Holocene.
Yet another new study (Caron et al., 2019) shows today’s Arctic sea ice cover is still quite extensive when compared to the last several thousand years, when CO2 concentrations ranged between 260 and 270 ppm.

Other new Arctic sea ice reconstructions from the north of Iceland (Harning et al., 2019) and Barents Sea (Berben et al., 2019) regions indicate a) modern sea ice extent has changed very little in the last several hundred years, or since the Little Ice Age, and b) the Early Holocene had millennial-scale periods of sea-ice-free and open water conditions, which is in stark contrast to “modern conditions” – the “highest value” or furthest extent of the sea ice record.

[T]he PBIP25 values [proxy for sea ice presence] reach their highest value (0.87) of the record at ca. 0 cal yr BP. An increase in PBIP25 suggests a further extension in sea ice cover, reflecting Arctic Front conditions (Müller et al., 2011), most similar to modern conditions.” (Berben et al., 2019)

 

For Most Of The Last 10,000 Years, Greenland Ice Sheet and Glacier Volume Was Smaller Than Today

by K. Richard, August 5, 2019 in NoTricksZone


A new paper (Axford et al., 2019) reveals NW Greenland’s “outlet glaciers were smaller than today from ~9.4 to 0.2 ka BP” (9,400 to 200 years before 1950), and that “most of the land-based margin reached its maximum Holocene extent in the last millennium and likely the last few hundred years.”

The authors conclude:

“We infer based upon lake sediment organic and biogenic content that in response to declining temperatures, North Ice Cap reached its present-day size ~1850 AD, having been smaller than present through most of the preceding Holocene.”

Furthermore, the authors assert Greenland was 2.5°C to 3°C warmer than modern on average during the Holocene Thermal Maximum, and peak temperatures were 4°C to 7°C warmer.

 

 

Image Source: Mikkelson et al., 2018

Fake “Heatwave for Greenland” Claims

by P. Homewood, July 30, 2019 in NotaLotofPeopleKnowThat


And that Greenland ice? The Surface Mass Balance has been well below normal throughout the winter, because of the dry weather. The rate of summer melt, however, has been pretty much normal, contrary to the fake claims of Ms Nullis.

With only a couple of weeks of melt left, it seems extremely unlikely that, even with the sunshine forecast, that the ice will dip below the 2012 figure (which incidentally is only a “record low” since records began in 1981).

http://polarportal.dk/en/greenland/surface-conditions/

Shockingly Thick First-Year Ice In Mid-July Between Barents Sea And North Pole

by S.J. Crockford, July29, 2019 in ClimateChangeDispatch


In late June, one of the most powerful icebreakers in the world encountered such extraordinarily thick ice on-route to the North Pole (with a polar bear specialist and deep-pocketed, Attenborough-class tourists onboard) that it took a day and a half longer than expected to get there.

A few weeks later, in mid-July, a Norwegian icebreaker also bound for the North Pole (with scientific researchers onboard) was forced to turn back north of Svalbard when it unexpectedly encountered impenetrable pack ice.

Apparently, the ice charts the Norwegian captain consulted showed ‘first-year ice‘ – ice that formed the previous fall, defined as less than 2 m thick (6.6 ft) – which is often much broken up by early summer.

However, what he and his Russian colleague came up against was consolidated first-year pack ice up to 3 m thick (about 10 ft). Such thick first-year ice was not just unexpected but by definition, should have been impossible.

Ice charts for the last few years that estimate actual ice thickness (rather than age) show ice >2 m thick east and/or just north of Svalbard and around the North Pole are not unusual at this time of year.

This suggests that the propensity of navigational charts to use ice ‘age’ (e.g. first-year vs. multi-year) to describe ice conditions could explain the Norwegian captain getting caught off-guard by exceptionally thick first-year ice.

Geoscientists discover mechanisms controlling Greenland ice sheet collapse

by University of South Florida (USF Innovation), July 19, 2019 in ScienceDaily/Nature


 

Greenland’s more than 860,000 square miles are largely covered with ice and glaciers, and its melting fuels as much as one-third of the sea level rise in Florida. That’s why a team of University of South Florida geoscientists’ new discovery of one of the mechanisms that allows Greenland’s glaciers to collapse into the sea has special significance for the Sunshine State.

New radar technology allowed geoscientists to look at Greenland’s dynamic ice-ocean interface that drives sea level rise.

Earlier this spring, NASA scientists reported Jakobshavn Glacier, which has been Greenland’s fastest -thinning glacier for the last 20 years, was slowing in its movement toward the ocean in what appears to be a cyclical pattern of warming and cooling. But because Jakobshavn is still giving up more ice than it accumulates each year, its sheer size makes it an important factor in sea level rise, the NASA scientists maintain.

“Our study helps understand the calving process,” Dixon said. “We are the first to discover that mélange isn’t just some random pile of icebergs in front of the glacier. A mélange wedge can occasionally ‘hold the door’ and keep the glacier from calving.”

Journal Reference:

  1. Surui Xie, Timothy H. Dixon, David M. Holland, Denis Voytenko, Irena Vaňkov�. Rapid iceberg calving following removal of tightly packed pro-glacial mélange. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-10908-4

2019 Climate “Ship Of Fools” Runs Into 3-Meter Thick Ice… Baffin Inlets Mid Summer Ice Extent No Trend in 50 Years

by P. Gosselin, July 19, 2019 in NoTricksZone


Our German skeptic friend Snowfan here keeps us up to date on the latest ODEN “Ship of Fools” attempt to travel across an Arctic that is supposed to be ice-free by now.

The incentive to cross the Arctic passages in the summer is huge. Doing so would mean at least a week of fame with the media blaring out your name along with grossly hyped headlines of an Arctic ice meltdown due to global warming. One of these years, a ship might get lucky and manage to get through the Northwest Passage.

Also defying the models is the extent of ice cover for July 9 at the Baffin inlets Regent – Boothia. Over the last 50 years, there’s been little trend change:

 

Source: Canadian Ice Service

Strong storms also play big role in Antarctic ice shelf collapse

by Oregon State University, July 18, 2019 in ScienceDaily


Warming temperatures and changes in ocean circulation and salinity are driving the breakup of ice sheets in Antarctica, but a new study suggests that intense storms may help push the system over the edge.

A research team led by U.S. and Korean scientists deployed three moorings with hydrophones attached seaward of the Nansen Ice Shelf in Antarctica’s Ross Sea in December of 2015, and were able to record hundreds of short-duration, broadband signals indicating the fracturing of the ice shelf.

The “icequakes” primarily took place between January and March of 2016, with the front of the ice sheet calving into two giant icebergs on April 7. The day the icebergs drifted away from the shelf coincided with the largest low-pressure storm system the region had recorded in the previous seven months, the researchers say.

Results of the study are being published this week in Frontiers in Earth Science.

Journal Reference:

  1. R. P. Dziak, W. S. Lee, J. H. Haxel, H. Matsumoto, G. Tepp, T.-K. Lau, L. Roche, S. Yun, C.-K. Lee, J. Lee, S.-T. Yoon. Hydroacoustic, Meteorologic and Seismic Observations of the 2016 Nansen Ice Shelf Calving Event and Iceberg Formation. Frontiers in Earth Science, 2019; 7 DOI: 10.3389/feart.2019.00183

Antarctic sea ice is declining dramatically

by Claire L. Parkinson, July 5, 2019 in WUWT


PNAS first published July 1, 2019 https://doi.org/10.1073/pnas.1906556116

Contributed by Claire L. Parkinson, May 24, 2019 (sent for review April 16, 2019; reviewed by Will Hobbs and Douglas G. Martinson)

Significance

A newly completed 40-y record of satellite observations is used to quantify changes in Antarctic sea ice coverage since the late 1970s. Sea ice spreads over vast areas and has major impacts on the rest of the climate system, reflecting solar radiation and restricting ocean/atmosphere exchanges. The satellite record reveals that a gradual, decades-long overall increase in Antarctic sea ice extents reversed in 2014, with subsequent rates of decrease in 2014–2017 far exceeding the more widely publicized decay rates experienced in the Arctic. The rapid decreases reduced the Antarctic sea ice extents to their lowest values in the 40-y record, both on a yearly average basis (record low in 2017) and on a monthly basis (record low in February 2017).

Abstract

Following over 3 decades of gradual but uneven increases in sea ice coverage, the yearly average Antarctic sea ice extents reached a record high of 12.8 × 106 km2 in 2014, followed by a decline so precipitous that they reached their lowest value in the 40-y 1979–2018 satellite multichannel passive-microwave record, 10.7 × 106 km2, in 2017. In contrast, it took the Arctic sea ice cover a full 3 decades to register a loss that great in yearly average ice extents. Still, when considering the 40-y record as a whole, the Antarctic sea ice continues to have a positive overall trend in yearly average ice extents, although at 11,300 ± 5,300 km2⋅y−1, this trend is only 50% of the trend for 1979–2014, before the precipitous decline. Four of the 5 sectors into which the Antarctic sea ice cover is divided all also have 40-y positive trends that are well reduced from their 2014–2017 values. The one anomalous sector in this regard, the Bellingshausen/Amundsen Seas, has a 40-y negative trend, with the yearly average ice extents decreasing overall in the first 3 decades, reaching a minimum in 2007, and exhibiting an overall upward trend since 2007 (i.e., reflecting a reversal in the opposite direction from the other 4 sectors and the Antarctic sea ice cover as a whole).

Fig. 1. Identification of the 5 sectors used in the regional analyses. These are identical to the sectors used in previous studies (7, 8).

Antarctic Sea Ice Suddenly Declined, But Scientists Warn: Don’t Blame Climate Change

by Adam Vaughan, July 3, 2019 in ClimateChangeDispatch


Decades of expanding sea ice in Antarctica have been wiped out by three years of sudden and dramatic declines, leaving scientist puzzled as to why the region has flipped so abruptly.

A new satellite analysis reveals that between 2014 and 2017 sea ice extent in the southern hemisphere suffered unprecedented annual decreases, leaving the area covered by sea ice at its lowest point in 40 years.

The declines were so big that they outstripped the losses in the fast-melting Arctic over the same period.

“It’s very surprising. We just haven’t seen decreases like that in either hemisphere,” says Claire Parkinson at NASA’s Goddard Space Flight Center, who undertook the analysis.

However, researchers cautioned against pinning the changes on climate change and said it was too early to say if the shrinking is the start of a long-term trend or a blip.

After growing for decades, Antarctic sea ice extent declined at an unprecedented rate between 2014 and 2017.

How geologic forces are melting southern Greenland ice sheet

by J.E. Kamis, May 25, 2016 in ClimateChangeDispatch


The most plausible scenario for southern Greenland’s surface ice melt is related to geologically induced heat flow and not atmospheric warming for various, well-established reasons. Based on research by the National Oceanic and Atmospheric Administration (NOAA) (see here), the top surface of southern Greenland’s ice sheet is currently melting at a high rate and therefore greatly reducing surface ice volume. They attribute this geographically localized melting effect to an unusually persistent and man-made atmospheric high pressure system (a so-called Omega Block) that has remained stationary above southern Greenland during the spring of 2016.

This non-moving high-pressure system has trapped a cell of very warm air above southern Greenland resulting in higher-than-normal surface ice melting rates and volumes. NOAA and the mainstream media are portraying this above-average melting as undeniable proof man-made global warming damaging our planet.

This portrayal is vastly misleading.

That’s because southern Greenland’s surface ice melt is more likely caused by natural, geologically induced heat flow from one of Earth’s largest Deep Ocean crustal plate junctures, the 10,000 mile long Mid-Atlantic Ridge (MAR). The Mid-Atlantic Ridge is “an immensely long mountain chain extending for about 10,000 miles (16,000 km) in a curving path from the Arctic Ocean to near the southern tip of Africa. The ridge is equidistant between the continents on either side of it. The mountains forming the ridge reach a width of 1,000 miles.”

Now 20 years with no trend in ice breakup dates for Western Hudson Bay polar bears

by Polar Bear Science, June  26, 2019


Straight from the horse’s mouth: all polar bear females tagged by researchers around Churchill in Western Hudson Bay last year were still on the ice as of 25 June. With plenty of ice still remaining over the bay, spring breakup will be no earlier this year than it has been since 1999. Contrary to predictions of ever-declining ice cover, the lack of a trend in sea ice breakup dates for Western Hudson Bay is now twenty years long (a hiatus, if you will) and yet these bears are repeatedly claimed to have been seriously harmed in recent years by a loss of sea ice.

 

Ice Melting In Greenland? That’s What It Does In Summer

by P. Homewood, June 20, 2019 in NotaLotofPeopleKnowThat


The first thing to point out is that this is nothing to do with Greenland’s ice sheet, despite the misleading inference to that effect in the first paragraph. It is in fact fjord ice, which freezes every winter and melts every summer.

This year it is beginning to melt slightly earlier than usual, because of warm air moving up from the south. This is called “weather”, and has nothing to do with “global warming”.

As is noted, such weather is not unprecedented. Indeed, the temperature peak of 17.3C is not even unusual for Qaanaaq, where the record is set at 20C.

 

See also here

New Paper: Arctic Sea Ice Was Far Less Extensive Than Today During The ‘Ice Free’ Early Holocene

by K. Richard, May 23, 2019 in NoTricksZone


Biomarker evidence for Arctic-region sea ice coverage in the northern Barents Sea indicates the most extensive sea ice conditions of the last 9,500 years occurred during the 20th century (0 cal yr BP). In contrast, this region was ice free with open water conditions during the Early Holocene (9,500-5,800 years ago).