GREENLAND MELTING ALARM OF 2020

vor 5 Std.

THIS POST IS A CRITICAL REVIEW OF A CBC ARTICLE [LINK] SAYING THAT FOSSIL FUELED ANTHROPOGENIC GLOBAL WARMING HAS CREATED A JULY 2020 HEATWAVE EVENT THAT IS CAUSING DANGEROUS ICE MELT ON THE GREENLAND ICE SHEET. THE MELT EVENT HAS LED TO FORECASTS OF CATASTROPHIC SEA LEVEL RISE AND SEA ICE LOSS. 

PART-1: WHAT THE ARTICLE SAYS

1. The heat wave that smashed high temperature records in five European countries a week ago is now over Greenland, accelerating the melting of the island’s ice sheet and causing massive ice loss in the Arctic. Greenland, the world’s largest island, lies between the Atlantic and Arctic oceans and has 82 per cent of its surface covered in ice. The area of the Greenland ice sheet that is showing indications of melt has been growing daily, and hit a record 56.5 per cent for this year on Wednesday, said Ruth Mottram, a climate scientist with the Danish Meteorological Institute. She says that’s expected to expand and peak on Thursday before cooler temperatures slow the pace of the melt.
2. More than 10 billion tonnes of ice was lost to the oceans by surface melt on Wednesday alone, creating a net mass ice loss of some 197 billion tonnes from Greenland in July, she said.
3. It looks like the peak will be today. But the long-term forecast is for continuing warm and sunny weather in Greenland, so that means the amount of the ice loss will continue,“ she said Thursday in a telephone interview from Copenhagen.
4. The scope of Wednesday’s ice melt is a number difficult to grasp. To understand just how much ice is being lost, a mere one billion tonnes — or one gigatonne — of ice loss is equivalent to about 400,000 Olympic-sized swimming pools, the Danish Meteorological Institute said. And 100 billion tonnes corresponds to a 0.28 mm rise in global sea levels.
5. July was world’s hottest month on record, WMO says
6. Mottram said since June 1 — roughly the start of the ice-loss season — the Greenland ice sheet has lost 240 gigatonnes this year. That compares with 290 gigatonnes lost overall in the 2012 melt season, which usually goes through the end of August.
7. A June 2019 study by scientists in the U.S. and Denmark said melting ice in Greenland alone will add between five and 33 centimetres to rising global sea levels by the year 2100. If all the ice in Greenland melted — which would take centuries — the world’s oceans would rise by 7.2 metres, the study found.
8. Travelling heat wave: The current melting has been brought on by the arrival of the same warm air from North Africa and Spain that scorched European cities and towns last week, setting national temperature records in Belgium, Germany, Luxembourg, the Netherlands and Britain.
9. In Russia, meanwhile, forest fires caused by hot, dry weather and spread by high winds are raging over nearly 30,000 square kilometres of territory in Siberia and the Russian Far East, an area the size of Belgium. Smoke from these fires, some of them in Arctic territory, is so heavy it can easily be seen in satellite photos and is causing air quality problems in Russia’s third-largest city, Novosibirsk.
10. Protesters in Moscow on Thursday were demanding that the government do more to fight the blazes. Greenland has also been battling a slew of Arctic wildfires, something that Mottram said was uncommon in the past.
11. In Greenland, the melt area this year is the second-biggest in terms of ice area affected, behind more than 90 per cent in 2012, said Mark Serreze, director of the National Snow and Ice Data Center in Boulder, Colo., which monitors ice sheets globally. Records go back to 1981. A lot of what melts can later refreeze onto the ice sheet, but because of the conditions ahead of this summer’s heat wave, the amount of ice lost for good this year might be the same as in 2012  or more, according to scientists. They noted a long buildup to this summer’s ice melt — including higher overall temperatures for months — and a very dry winter with little snow in many places, which would normally offer some protection to glacier ice. „This is certainly a weather event superimposed on this overall trend of warmer conditions“ that have increasingly melted Greenland ice over the long term, Serreze said.
12. Compounding the melt, the Greenland ice sheet started out behind this year because of the low ice and snow accumulation, said Snow and Ice Data Center scientist Twila Moon.
13. Increased frequency:  With human-caused climate change, „there’s a potential for these kind of rates to become more common 50 years from now,“ Moon said. Heat waves have always occurred, but Mike Sparrow, a spokesperson for the UN World Meteorological Organization, noted that as global temperatures have risen, extreme heat waves are now occurring at least 10 times more frequently than a century ago. This year, the world saw its hottest month of June ever.
14. These kinds of heat waves are weather events and can occur naturally but studies have shown that both the frequency and intensity of these heat waves have increased due to global warming,“ Sparrow said in a telephone interview from Geneva. He noted that sea ice extent in the Arctic and Antarctic are both currently at record lows. 10 warmest years in U.K. all happened after 2002, climate report says. Europe’s record heat wave moves toward Greenland, threatening world’s 2nd largest ice sheet.
15. „When people talk about the average global temperature increasing by a little more than one degree (Celsius), that’s not a huge amount to notice if you’re sitting in Hamburg or London, but that’s a global average and it’s much greater in the polar regions,“ he said. Even though temperatures will be going down in Greenland by the end of this week, the ice melt is not likely to stop any time soon, Mottram said.
16. „Over the last couple of days, you could see the warm wave passing over Greenland,“ she said. „That peak of warm air has passed over the summit of the ice sheet, but the clear skies are almost as important, or maybe even more important, for the total melt of the ice sheet.“ She added that clear skies are likely to continue in Greenland „so we can still get a lot of ice melt even if the temperature is not spectacularly high.“

PART-2: CRITICAL COMMENTARY

1. THE INTERNAL VARIABILITY ISSUE: Anthropogenic global warming and climate change (AGW) is a theory about the impact of fossil fuel emissions on long term trends (longer than 30 years) in global–mean temperature. In a related post [LINK] we describe the climate science position on the issue of interpreting localized short term weather events in the context of AGW and specifically as „impacts“ of AGW.  What we find there is that short term localized events such as the Greenland Ice Sheet melt ponds of July 2020 cannot be attributed to AGW because “ Internal variability in the climate system confounds assessment of human-induced climate change and imposes irreducible limits on the accuracy of climate change projections, especially at regional geographical spans and decadal time scales.
2. The observed melt ponds on the Greenland Ice Sheet that has alarmed climate change analysts at the CBC should be understood in this context. Although the whole of the Arctic region is a sufficient global span, even in that case, the climate oddities being studied in the context of AGW would require time spans of 30 years or more. The climate events in question, however, are highly localized to the surface of melt pond formation on the surface of the Greenland Ice Sheet and with the time scale constrained to a weather event over a few days in the extreme melt month of July. In light of the internal variability issue, this event cannot be interpreted in terms of AGW.
3. Additional arguments against the attribution of these events to to fossil fuel emissions of the Industrial Economy (and the assumed implication of the ability of climate action to moderate these melt events) is found in the paleo data of ice melt on the Greenland Ice Sheet presented in the bibliography below. The literature shows that melt events of the nature described by the CBC and melt events more extreme than that found by the CBC in July 2020, are also found in earlier Holocene melt epochs long before the Industrial Revolution.
4. Specifically we note in papers such as Luthi 2015 cited below, that episodic internal geothermal heat must also be considered in the analysis of Greenland Ice sheet melt events. The relevant geological features of the Arctic are described in a related post [LINK] .
5. The CBC article makes a references to the Siberian heat wave. This issue is discussed in a related post [LINK]  .

PART-3: THE RELEVANT BIBLIOGRAPHY

1. Jennings, Anne E., et al. „Paleoenvironments during Younger Dryas‐E arly Holocene retreat of the Greenland Ice Sheet from outer Disko Trough, central west Greenland.“ Journal of Quaternary Science 29.1 (2014): 27-40.  Paleoenvironments during the late Younger Dryas through early Holocene retreat of the Greenland Ice Sheet from the outer shelf in the Disko Trough system of central West Greenland were investigated via lithofacies, foraminifera, dinocysts and sediment provenance analyses in radiocarbon‐dated sediment cores from the upper slope (JR175‐VC35) and outer shelf (JR175‐VC20 and HU2008029‐070CC). Core data show that the ice margin retreated rapidly from the outer shelf by calving, beginning by 12.2k cal a BP under cold paleoceanographic conditions with up to 11 months of sea‐ice. Ice retreat into Disko Bugt was well underway by 10.9k cal a BP. Enhanced ice‐sheet ablation in Disko Bugt and elsewhere along the West Greenland coast is inferred from cold glacial marine conditions associated with high sedimentation rates between 10.9 and 9.5k cal a BP on the outer shelf. Glacial marine conditions are recorded on the outer shelf until 7.8k cal a BP. Detrital carbonate‐bearing sediments rich in >2‐mm clasts deposited between 11.6 and 10.6 k cal a BP indicate that icebergs calved from northern Baffin Bay ice margins were melting and releasing sediments along West Greenland while the Greenland Ice Sheet margin was retreating into Disko Bugt.
2. Neff, William, et al. „Continental heat anomalies and the extreme melting of the Greenland ice surface in 2012 and 1889.“ Journal of Geophysical Research: Atmospheres 119.11 (2014): 6520-6536.  Recent decades have seen increased melting of the Greenland ice sheet. On 11 July 2012, nearly the entire surface of the ice sheet melted; such rare events last occurred in 1889 and, prior to that, during the Medieval Climate Anomaly. Studies of the 2012 event associated the presence of a thin, warm elevated liquid cloud layer with surface temperatures rising above the melting point at Summit Station, some 3212 m above sea level. Here we explore other potential factors in July 2012 associated with this unusual melting. These include (1) warm air originating from a record North American heat wave, (2) transitions in the Arctic Oscillation, (3) transport of water vapor via an Atmospheric River over the Atlantic to Greenland, and (4) the presence of warm ocean waters south of Greenland. For the 1889 episode, the Twentieth Century Reanalysis and historical records showed similar factors at work. However, markers of biomass burning were evident in ice cores from 1889 which may reflect another possible factor in these rare events. We suggest that extreme Greenland summer melt episodes, such as those recorded recently and in the late Holocene, could have involved a similar combination of slow climate processes, including prolonged North American droughts/heat waves and North Atlantic warm oceanic temperature anomalies, together with fast processes, such as excursions of the Arctic Oscillation, and transport of warm, humid air in Atmospheric Rivers to Greenland. It is the fast processes that underlie the rarity of such events and influence their predictability. [FULL TEXT]
3. Lüthi, Martin P., et al. „Heat sources within the Greenland Ice Sheet: dissipation, temperate paleo-firn and cryo-hydrologic warming.“ The Cryosphere 9.1 (2015): 245-253.  Ice temperature profiles from the Greenland Ice Sheet contain information on the deformation history, past climates and recent warming. We present full-depth temperature profiles from two drill sites on a flow line passing through Swiss Camp, West Greenland. Numerical modeling reveals that ice temperatures are considerably higher than would be expected from heat diffusion and dissipation alone. The possible causes for this extra heat are evaluated using a Lagrangian heat flow model. The model results reveal that the observations can be explained with a combination of different processes: enhanced dissipation (strain heating) in ice-age ice, temperate paleo-firn, and cryo-hydrologic warming in deep crevasses. [FULL TEXT]