Archives par mot-clé : Arctic

Facts About the Arctic in May 2022

by J. Hunt, Apr 30, 2022 in TheGreatWhite Con


 

There’s a few things to note at first glance. The ice floe continued to decrease in thickness into November. It’s thickness then started to increase, but is currently still less than 2 meters. Also the snow depth has gradually been increasing, and (apart from some data glitches!) is now ~38 cm. Finally, for the moment at least, the ice surface temperature has been slowly warming since mid February and is now ~-11 °C.

 

Arctic Sea Ice Stabilizes, No Trend Reduction In More Than 10 Years As Solar Cycle Starts Off Weakly

by P. Gosselin, Apr 27, 2022 in NoTricksZone


The Copernicus program offers very interesting data on Arctic ice.

While sea ice has been declining off the Greenland Sea (east of the island), the Chucki Sea (eastern Siberia) shows a very different trend in sea ice extent over the past year. Such deviations have occurred repeatedly since the year 2000.

Overall, the 2021 extent was very close to the 1991-2020 mean and well above the lowest value in 2012 and also above what was recorded in the year 2020

Sea ice average for March is the metric used to compare to previous winters

by S. Crockford, Apr 5, 2022 in PolarBearScience


The average sea ice cover at the end of March is the metric used to compare ‘winter’ ice to previous years or decades, not the single-day date of ‘most’ ice. This year, March ended with 14.6 mkm2 of sea ice, most of which (but not all) is critical polar bear habitat. Ice charts showing this are below.

But note that ice over Hudson Bay, which is an almost-enclosed sea used by thousands of polar bears at this time of year, tends to continue to thicken from March into May: these two charts for 2020 show medium green becoming dark green, indicating ice >1.2 m thick, even as some areas of open water appear.

Arctic Ocean Warming Began Already In Early 20th Century, Meaning Natural Factors Strongly At Play, Not CO2

by University of Cambridge, Dec 29, 2021 in NoTricksZone


In a recent paper, scientists expressed their surprise that the Arctic had started warming already back in the early 20th century, 100 years ago. This, along with the obligatory CO2 climate warming lip service, is described in a Cambridge University press release.

Natural oceanic currents

The Arctic Ocean has been getting warmer since the beginning of the 20th century—decades earlier than records suggest—due to warmer water flowing into the delicate polar ecosystem from the Atlantic Ocean.

An international group of researchers reconstructed the recent history of   at the gateway to the Arctic Ocean in a region called the Fram Strait, between Greenland and Svalbard.

The researchers used geochemical and ecological data from ocean sediments to reconstruct the change in water column properties over the past 800 years. They precisely dated sediments using a combination of methods and looked for diagnostic signs of Atlantification, like change in temperature and salinity.

“When we looked at the whole 800-year timescale, our temperature and salinity records look pretty constant,” said co-lead author Dr. Tesi Tommaso from the Institute of Polar Sciences of the National Research Council in Bologna. “But all of a sudden at the start of the 20th century, you get this marked change in temperature and salinity—it really sticks out.”

“The reason for this rapid Atlantification of at the gate of the Arctic Ocean is intriguing,” said Muschitiello. “We compared our results with the ocean circulation at lower latitudes and found there is a strong correlation with the slowdown of dense water formation in the Labrador Sea. In a future warming scenario, the deep circulation in this subpolar region is expected to further decrease because of the thawing of the Greenland ice sheet. Our results imply that we might expect further Arctic Atlantification in the future because of climate change.”

The researchers say that their results also expose a possible flaw in climate models, because they do not reproduce this early Atlantification at the beginning of the last century.

Promoters of polar bear catastrophe in Hudson Bay gloss over recent good ice conditions

by S. Crockford, Dec 8, 2021 in PolarScience


Hudson Bay has been oddly slow to freeze this year, which has led to a predictable bit of hand-wringing from certain biologists reiterating prophesies of polar bear population collapse. However, since 2009, the last time that freeze-up was anywhere near this late was 2016. In other words, far from this years’ late freeze-up being a picture of ‘the new normal,’ conditions in 2021 are actually unusual compared to the last twelve years.

Perhaps the last bear leaving Cape Churchill for the sea ice, 4 December 2021.

Moreover, considering that 2021 fall ice formation for the Arctic in general is well ahead of 2016 (and every year since, except 2018), it’s hard to see why human-caused global warming caused by ever-increasing CO2 emissions explains the slow freeze-up of Hudson Bay. Timing of Hudson Bay freeze-up has always been highly variable from one year to the next (Castro de la Guardia et al. 2017: Fig. 3, copied below). The average freeze-up date in the 1980s was 16 November ± 5 days, while from 2005-2015 this had shifted about a week to 24 November ± 8 days (Castro de la Guardia et al. 2017:230). This year freeze-up was later than usual but last year and the three years before that the ice froze as early as it did in the 1980s. Cue the zombie apocalypse.

The Arctic Ocean began warming decades earlier than previously thought, new research shows

by P. Homewood, Nov 27, 2021 in NotaLotofPeopleKnowThat


A new study throws doubt on the theory that Arctic warming is man made.

The Arctic Ocean has been warming since the onset of the 20th century, decades earlier than instrument observations would suggest, according to new research.

The study, published Wednesday in the journal Science Advances, found that the expansion of warm Atlantic Ocean water flowing into the Arctic, a phenomenon known as “Atlantification,” has caused Arctic water temperature in the region studied to increase by around 2 degrees Celsius since 1900.

Francesco Muschitiello, an author on the study and assistant professor of geography at the University of Cambridge, said the findings were worrisome because the early warming suggests there might be a flaw in the models scientists use to predict how the climate will change.

Deep freeze in Arctic Europe sends power prices soaring

by T. Nilsen, Nov 28, 2021 in The BarentsObserver


On the Finnmark plateau, between Kautokeino and Karasjok, temperatures dropped down to -35°C on Sunday. The forecast for the coming week shows a temperature anomaly for the last days of November of 10°C below the reference period 1961-1990, the Swedish Meteorological and Hydrological Institute informs.

Coldest out is Nikkaluokta near Gällivare in Norrbotten with -36°C.

In times of climate change, the current freeze comes in sharp contrast to last fall, when meteorologists reported about the hottest October and early November ever measured, with an average of 6,7°C above normal across the Arctic.

Cold weather even sweeps the coast of northernmost Norway where the Arctic waters are kept ice-free by the warm Gulf Stream. In Kirkenes, on the border to Russia, the thermometer read -25°C on Saturday outside the Barents Observer’s office.

On the Kola Peninsula, Sunday November 28 came with temperatures from -18°C to -30°C the news online Severpost reported.

Further east in the Russian Arctic, quickly accumulating sea-ice on the Northern Sea Route has created a critical situation as a number of ships have been trapped in thick sea-ice for several weeks.

Inari, northern Finland. Photo: Thomas Nilsen

NASA Data On Global Sea Ice Area Shows A Growth Equal To The Size Of Belgium Since 1982!

by P. Gosselin,  Nov 30, 2021 in NoTricksZone


Data sources like the National Snow and Ice Data Center show global sea ice has been” drastically decreasing for a long time” and so we need to panic and overhaul the entire carbon economy. We hear this daily in the media.

Surprising global sea ice area findings

But Zoe has analyzed what she characterizes as a “very legitimate source” of data from NASA, (here, or here). And according to her findings, the data from these sources suggest global sea ice loss is not as dramatic as some institutes would like us to believe it is. In fact there ‘s been a gain!

Zoe plotted the data going back 40 years, from 1982 to 2021, the “Global Sea Ice Area Fraction”, which “is a proportion of the entire Earth’s surface that is ice over water.”

“As you can see, about 3.6% (on average) of our planet’s area is covered in ice over water,” reports Zoe. “In the last 40 years, ice over water has INCREASED, and not decreased, as popularly claimed.”

According to Zoe, the observed increase is equivalent to ~30,600 km², or “roughly the size of Belgium”.

Climate Fail: Arctic Sea Ice Growing, Nearing Highest Extent In Two Decades

by T. Lison, Nov 24, 2021 in ClimateChangeDispatch


 

t’s so cold in the Arctic that:

Two icebreakers are on the way to rescue ice-locked ships on Northern Sea Route (snip)

District authorities in the Russian Far East have decided to commission two icebreakers to aid the vessels currently ice-locked in the East Siberian Sea. (snip)

The commissioning of the powerful icebreaking vessels comes as severe sea-ice conditions have taken shippers by surprise. There are now about 20 vessels that either are stuck or struggling to make it across the icy waters.

But what about the Antarctic ice cap?

That’s not about to melt either:

[T]he South Pole also just witnessed a historically cold winter. As reported last month: “Between the months of April and September, the South Pole averaged a temperature of -61.1C (-78F). Simply put, this was the region’s coldest 6-month spell ever recorded, and it comfortably usurped the previous coldest ‘coreless winter‘ on record: the -60.6C (-77F) from 1976 (solar minimum of weak cycle 20).”

In  fact, it turns out that, according to a study released a week ago:

PALEOCLIMATE DATA INDICATE THERE WAS LESS ARCTIC SEA ICE DURING THE PRE-INDUSTRIAL PERIOD THAN IN MODERN TIMES, OR WHEN CO2 CONCENTRATIONS WERE 100 PPM LOWER THAN TODAY (280 VS. 380 PPM).

Scientists (Diamond et al., 2021) assert that during the 18th and 19th centuries Arctic sea ice extent minimum (September) values averaged 5.54 million km².

SHARP UPTICK IN ARCTIC SEA ICE: EXTENT ON COURSE TO BE THE HIGHEST IN 15 YEARS

by Cap Allon, Aug 28, 2021 in Electroverse


Arctic Sea Ice Extent has been holding exceptionally well during the 2021 summer melt season.

Throughout August, higher volumes than usual have survived due to cold conditions and favorable wind patterns.

As a result, Arctic Sea Ice Extent is now the highest in 8 years, and, if this year’s trajectory continues for another week or two (which is expected), 2021 will achieve the ‘healthiest’ extent of the past 15 years (since 2006).

Only 2014, 2013, and 2009 remain in its way–though the gap is narrowing, fast:

Stalled: September Arctic Sea Remains Surprisingly Stable Over Past Decade, “Long Way From Predicted “Ice Free”

by P. Gosselin, Sept 10, 2021 in NoTricksZone


This year’s Arctic sea ice minimum reaches third highest level in a decade, latest data show.

Die kalte Sonne here presents its latest climate video. The first part looks at this year’s Arctic sea ice melt season. Now that it’s September, sea ice extent has just about reached its minimum for the year and soon the annual refreeze will begin.

We recall that years ago alarmist scientists and wacko activists, like al Gore, predicted an ice free Arctic by now. Today we look at the most recent data and we see that we are a very long way from that point.

Very slow August melt this year

What follows is the chart from the National Snow and Ice Data Center (NSIDC):

Is The Earth Actually Getting Hotter?

by V. Jayaraj, Aug 2, 2021 in ClimateChangeDispatch


Every year, climate-change enthusiasts tell us the earth is getting hotter. Phys.org warned the world, “New ‘hottest year on record’ likely to occur in the next five years.”

C2ES informed readers, “It’s certain: The Earth is getting warmer, and human activity is largely to blame.” Bulletin of the Atomic Scientists’ headline read, “Broken record: The planet is getting hotter. And hotter. And hotter.”

But are we really observing record hot years consecutively?

While global warming is real and has been happening since the end of the Little Ice Age in the 18th century, the claims surrounding unprecedented temperatures are, at best, highly dubious.

Reality and some climate change claims differ as much as day and night. Here are two examples.

Strange Things: Readjusted Data Points

A few official agencies across the globe are widely considered “leaders” or “authoritative” in disseminating climate data.

Among them is the Met Office in the UK and top U.S. state agencies like the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA).

However, these agencies have used their near-invincible status to adjust climate data points as they please, often resulting in an exaggerated warming trend.

NASA has been found to have adjusted past temperature data downward to make the present temperature levels look comparatively warmer.

In July 2021, geologist Roger Higgs demonstrated how NASA lowered the 2016 data point for annual global mean temperature.

NASA carried out the supposed downward shifting of data points so that the temperature levels for 2020 (which were about the same as 2016) would now appear more extreme. Higgs revealed the downward shifting on Researchgate.

Why did NASA adjust the 2016 data point to make it appear that 2020 beat it by a larger margin than originally appeared? You decide.

Growth of Glaciers: Greenland Registers Historic Increase in Surface Mass Balance for July 2021

Greenland ice has been a topic of discussion ever since climate change became a headline item in news circles. The reduction of ice mass is often projected as proof of global warming.

New Study Casts Doubt On Controversial Theory Linking Melting Arctic To Severe Winter Weather

by P. Voosen, May 13, 2021 in ClimagteChangeDispatch


Every time severe winter weather strikes the United States or Europe, reporters are fond of saying that global warming may be to blame.

The paradox goes like this: As Arctic sea ice melts and the polar atmosphere warms, the swirling winds that confine cold Arctic air weaken, letting it spill farther south.

But this idea, popularized a decade ago [and was the outlandish plotline in The Day After Tomorrow, pictured], has long faced skepticism from many atmospheric scientists, who found the proposed linkage unconvincing and saw little evidence of it in simulations of the climate.

Now, the most comprehensive modeling investigation into this link has delivered the heaviest blow yet: Even after the massive sea ice loss expected by midcentury, the polar jet stream will only weaken by tiny amounts—at most only 10% of its natural swings.

And in today’s world, the influence of ice loss on winter weather is negligible, says James Screen, a climate scientist at the University of Exeter and co-leader of the investigation, which presented its results last monthat the annual meeting of the European Geosciences Union.

Wandering polar bears are the new starving polar bears, falsely blamed on climate change

by Polar Bear Science, May 15 , 2021


Back in 2017, we famously had National Geographic falsely blaming a starving polar bear on climate change but since then we have been inundated (relatively speaking) with stories of ‘wandering’ bears sighted far from Arctic coastlines. These wandering bears are oddities to be sure but are not in any way an indicator of melting Arctic sea ice or lost habitat, as The Times (UK) has claimed in this latest example (Polar bear treks 1,500 miles south as Arctic hunting zone melts away).

Arctic Sea Ice Extent Higher Than 2006

by P. Homewood, April 6, 2021 in NotaLotofPeopleKnowThat


Seventh lowest? The NSIDC would of course like you to believe that this is all part of a declining trend. In reality, since the sharp decline beginning in 2004, sea ice extent has gone up and down, but with little overall change. This year and last year, average March extent has actually been higher than in 2006.

http://ocean.dmi.dk/arctic/icecover_30y.uk.php

 

This March, extent was the 8th highest in the last 18 years, putting it around the median.

What about prior to 2004 though? Should we not be comparing this year with the 1981-2010 average?

Like it or not, and whatever the reason, the loss of summer ice in 2007 has had a direct effect on sea ice at all times of year since. Much of the sea ice is now thin, new ice, which melts more readily in summer. Consequently, winter ice takes longer to form as well.

It would probably take a climatic regime shift, such as occurred in the 1960s, for ice to return to pre 2004 levels. But the evidence shows that winter sea ice extent is currently stable.

 

Polar bear sea ice habitat highs and lows in early February

by Polar Bear Science, Feb 10, 2021


Sea ice across the Arctic in the first week of February is a mix of highs and lows. Bering Sea is back up to almost normal coverage, as is the Barents Sea. However, ice coverage on the East Coast of Canada is the lowest its been in four decades. This is not yet a worry for polar bears because harp seals don’t pup until mid-March in this region so there is at least four weeks of potential ice growth that can happen before the seals are forced to pup on much reduced ice – where polar bears are sure to find them.

Journal Nature Refutes PIK’s Fantasy-Rich Science That A Warmer Arctic Causes Extreme Cold Snaps

by P. Gosselin, Feb 9, 2021 in NoTricksZone


The polar vortex theory takes a beating: The claim a warm Arctic is behind the brutally cold winter conditions at the mid latitudes is shown by a Nature study to be scientifically baseless.

Now that Europe and North America are getting blasted by unusually severe winter weather, which climate alarmists predicted 20 years ago would be a thing of the past, the alarmists are desperate to find an explanation to escape embarrassment.

PIK science suggests warmth begets cold

They’ve come up with the polar vortex explanation: the bitter cold we are now experiencing at the middle latitudes is in fact due to the warmer Arctic, they say. And this wreaks havoc on the jet stream which in turn results in cold Arctic blasts dipping deep into the middle latitudes. Yes, cold winters are in fact exactly what we should expect in a rapidly warming world!

Levermann and Rahmstorf

For example the two media front men Anders Levermann and Stefan Rahmstorf of the Potsdam Climate Institute (PIK) have been telling this to the ever gullible German media outlets, like Bild and Spiegel. Yet, many suspect it’s scientific fraud designed to fool the public and to hide the fact that their global warming predictions are in reality glaring failures.

Journal Nature refutes fantasy-rich PIK explanation

For example a recent paper appearing in Nature titled “Weakened evidence for mid-latitude impacts of Arctic warming“, authored by Blackport et al, refutes this highly fantasy-rich hypothesis pitched by the two PIK scientists.

 

Study Shows Arctic Sea Ice Reached Lowest Point On Modern Record… In The 1940s, Not Today!

by C. Rotter, Jan 24, 2021 in WUWT


Regular NoTricksZone author Kenneth Richards notes on Twitter

Apparently Arctic sea ice volume was as low in the 1940s as it has been in the 2000s.

And the highest sea ice volume of the last 100 years was about 1979 – the year the Arctic sea ice record begins.

 

Guillian Van Achter1, Leandro Ponsoni1, François Massonnet1, Thierry Fichefet1, and Vincent Legat2

  • 1Georges Lemaitre Center for Earth and Climate Research, Earth and Life Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
  • 2Institute of Mechanics, Materials and Civil Engineering, Applied Mechanics and Mathematics, Université Catholique de Louvain, Louvain-la-Neuve, Belgium

Correspondence: Guillian Van Achter (guillian.vanachter@uclouvain.be) Received: 04 Dec 2019 – Discussion started: 10 Dec 2019 – Revised: 17 Jul 2020 – Accepted: 09 Sep 2020 – Published: 21 Oct 2020

Abstract

We use model simulations from the CESM1-CAM5-BGC-LE dataset to characterise the Arctic sea ice thickness internal variability both spatially and temporally. These properties, and their stationarity, are investigated in three different contexts: (1) constant pre-industrial, (2) historical and (3) projected conditions. Spatial modes of variability show highly stationary patterns regardless of the forcing and mean state. A temporal analysis reveals two peaks of significant variability, and despite a non-stationarity on short timescales, they remain more or less stable until the first half of the 21st century, where they start to change once summer ice-free events occur, after 2050.

How to cite. Van Achter, G., Ponsoni, L., Massonnet, F., Fichefet, T., and Legat, V.: Brief communication: Arctic sea ice thickness internal variability and its changes under historical and anthropogenic forcing, The Cryosphere, 14, 3479–3486, https://doi.org/10.5194/tc-14-3479-2020, 2020.1

More food for Polar Bears: Arctic report card 2020 highlights the huge benefit of less summer sea ice

by Polar Bear Science, Jan 8, 2021 in WUWT


As well as summarizing sea ice changes, NOAA’s 2020 Arctic Report Card features two reports that document the biggest advantage of much less summer sea ice than there was before 2003: increased primary productivity. Being at the top of the Arctic food chain, polar bears have been beneficiaries of this phenomenon because the Arctic marine mammals they depend on for food – seals, walrus and bowhead whales – have been thriving despite less ice in summer.

In the sea ice chapter (Perovich et al. 2020), my favourite of all the figures published is the graph of September vs. March sea ice (above). As you can see, March ice extent has been virtually flat (no declining trend) since 2004. And as the graph below shows, September extent has been without a trend since 2007, as NSIDC ice expert Walt Meier demonstrated last year (see below): it doesn’t take much imagination to see that the value for 2020 from the graph above (the second-lowest after 2012) hasn’t changed the flat-trend line.

ELEVEN YEARS AGO TODAY AL GORE PREDICTED THE NORTH POLE WOULD BE COMPLETELY ICE FREE IN FIVE YEARSp

by Cap Allon, Dec 13, 2020 in Electroverse


On December 13 & 14, 2009, professor, prophet, and soothsayer Al Gore predicted the North Polar Ice Cap could be completely ice free within the next five to seven years.

 

Gore made his prediction at COP15 Copenhagen which ran from Dec 7 – Dec 18, 2009, where he repeatedly referenced “state-of-the-art” computer modeling to suggest that the north polar ice cap may lose all of its ice by 2014.

“Some of the models suggest that there is a 75 percent chance that the entire north polar ice cap, during some of the summer months, could be completely ice-free within the next five to seven years,” Gore claimed.

“Join me in asking president Obama and the US Senate to set a deadline of 22 April for final action in the US Senate,” he said. “I do not believe we can wait till next November or December.”

The Guardian wrote on Dec 16, 2009 in an article entitled “Al Gore rallies the troops in Copenhagen“:

[Gore] kept up the pace by calling for the international community to sign up to a fully fledged climate change treaty by July 2010 – and then announcing that Mexico was prepared to host a deal-making summit.

He scolded rich countries for demanding the developing world offer evidence of emissions cuts while at the same time trying to inflate the funds they were prepared to offer poor countries to deal with climate change. And he was just as tough on activists who have embraced him as a hero, demanding they set aside their pride and their principles and embrace a deal – no matter how imperfect. He said he recognized their frustration with the glacial pace of negotiations. He agreed that cap-and-trade schemes to cut carbon emissions were an imperfect solution – Gore confessed to favoring a carbon tax – but the current efforts for a deal were the best prospect of avoiding catastrophic climate change.

And there was no trace of sympathy for opponents of action on climate change. Gore began with a brief run-through of the latest science on melting of the Arctic ice cap, evidence he said “only reckless fools would ignore.”

Newly Discovered Greenland Plume Drives Thermal Activities in the Arctic

by C. Rotter, Dec 29, 2020  in WUWT


A team of researchers understands more about the melting of the Greenland ice sheet. They discovered a flow of hot rocks, known as a mantle plume, rising from the core-mantle boundary beneath central Greenland that melts the ice from below.

The results of their two-part study were published in the Journal of Geophysical Research.

“Knowledge about the Greenland plume will bolster our understanding of volcanic activities in these regions and the problematic issue of global sea-level rising caused by the melting of the Greenland ice sheet,” said Dr. Genti Toyokuni, co-author of the studies.

The North Atlantic region is awash with geothermal activity. Iceland and Jan Mayen contain active volcanoes with their own distinct mantle plumes, whilst Svalbard – a Norwegian archipelago in the Arctic Ocean – is a geothermal area. However, the origin of these activities and their interconnectedness has largely been unexplored.

The research team discovered that the Greenland plume rose from the core-mantle boundary to the mantle transition zone beneath Greenland. The plume also has two branches in the lower mantle that feed into other plumes in the region

 

Polar bears again attracted to Russian town by dead walrus Attenborough blames on no sea ice

by Polar Bear Science, Dec 20, 2020


In the news again: Cape Schmidt (on the Chukchi Sea) made famous by Sir David Attenborough’s false claim that walrus fell to their deaths because of lack of sea ice due to climate change when a clever polar bear hunting strategy was actually to blame.

Last year in December (above), some bears were feeding at Ryrkaypiy’s garbage dump and wandering around town after being displaced from feeding on walrus carcasses by bigger, stronger bears on the nearby point.

This year, the town has managed to keep the bears out of town, so while the residents are having no real problems, more than 30 bears have been spotted near town, almost certainly feeding on natural-death carcasses of walrus along the shore (see photo below from 2017 where Ryrkaypiy can be seen in the background).

 

Newly discovered Greenland plume drives thermal activities in the Arctic

by Tohoku University, Dec 7, 2020 in ScienceDaily


A team of researchers understands more about the melting of the Greenland ice sheet. They discovered a flow of hot rocks, known as a mantle plume, rising from the core-mantle boundary beneath central Greenland that melts the ice from below.

The results of their two-part study were published in the Journal of Geophysical Research.

“Knowledge about the Greenland plume will bolster our understanding of volcanic activities in these regions and the problematic issue of global sea-level rising caused by the melting of the Greenland ice sheet,” said Dr. Genti Toyokuni, co-author of the studies.

The North Atlantic region is awash with geothermal activity. Iceland and Jan Mayen contain active volcanoes with their own distinct mantle plumes, whilst Svalbard — a Norwegian archipelago in the Arctic Ocean — is a geothermal area. However, the origin of these activities and their interconnectedness has largely been unexplored

 

Claim: The climate changed rapidly alongside sea ice decline in the north

by University of Copenhagen, Dec 6, 2020 in WUWT


Researchers from the Niels Bohr Institute, University of Copenhagen have, in collaboration with Norwegian researchers in the ERC Synergy project, ICE2ICE, shown that abrupt climate change occurred as a result of widespread decrease of sea ice. This scientific breakthrough concludes a long-lasting debate on the mechanisms causing abrupt climate change during the glacial period. It also documents that the cause of the swiftness and extent of sudden climate change must be found in the oceans.

Scientific evidence for abrupt climate change in the past finally achieved

During the last glacial period, app. 10,000 – 110,000 years ago the northern hemisphere was covered in glacial ice and extensive sea ice, covering the Nordic seas. The cold glacial climate was interrupted by periods of fast warmup of up to 16.5 degrees Celsius over the Greenland ice sheet, the so called Dansgaard Oeschger events (D-O).

These rapid glacial climate fluctuations were discovered in the Greenland ice core drillings decades ago, but the cause of them have been hotly contested. D-O events are of particular significance today as the rate of warming seems to be very much like what can be observed in large parts of the Arctic nowadays. The new results show that the abrupt climate change in the past was closely linked to the quick and extensive decline in sea ice cover in the Nordic seas. Very important knowledge as sea ice is presently decreasing each year.

“Our, up until now, most extensive and detailed reconstruction of sea ice documents the importance of the rapid decrease of sea ice cover and the connected feedback mechanisms causing abrupt climate change”, says Henrik Sadatzki, first author of the study.

Sediment core and ice core data were combined in order to achieve the result