Archives par mot-clé : Holocene

PERMAFROST AND CLIMATE CHANGE IN ICELAND

by B. Van Vliet-Lanoé & A. Gudmundsson, Feb 2020, in ResearchGate


Permafrost developed from Termination Ia (Bölling interstadial, 14.5 cal ka BP) in Northern Iceland, in answer to deglaciation. Permafrost persisted or even re-extended during the Preboreal cooling events (at 11.2, 10.3 and 9.3 cal ka BP) synchronic with pulsated glacial advances. It disappeared below 1000 masl during the Thermal Optimum (8-5 cal ka BP). The present-day re-extent was controlled with the cooling related with the Little Ice Age and particularily the Maunder solar Minimum. Continuous permafrost is stable above 1000 masl, but is today melting between 900 and 800 masl. Discontinuous permafrost is vanishing today with the recent climate warming (from 1970), especially in palsa bogs, and on valley slopes with thermokarstic mass wasting.

Holocene ice-free strait followed by dynamic Neoglacial fluctuations: Hornsund, Svalbard

by A. Osaka et al., Apr 25, 2022 in TheHolocene


Keywords

The recession of the Hornbreen-Hambergbreen glaciers (Hornsund, Svalbard) will lead to the formation of a strait between the Greenland and Barents Seas within a few decades. We provide evidence for the earlier existence of this strait, in the Early–Middle Holocene and presumably since 1.3 ka cal. BP until glacier advance 0.7 ± 0.3 ka or earlier. Radiocarbon dating of mollusc shells from the ground moraines in the Hornbreen forefield indicate the existence of the marine environment at the contemporary glacierized head of Hornsund since 10.9 ka cal. BP or earlier due to glacier retreat. The gap in the radiocarbon dates between 3.9 and 1.3 ka cal. BP and the published results of 10Be exposure dating on Treskelen suggest the strait’s closure after glacier advance in the Neoglacial. Subsequent re-opening occurred around 1.3 ka cal. BP, but according to 10Be dates from Treskelen, the strait has again been closed since ca. 0.7 ± 0.3 ka or earlier. The oldest known surge of Hornbreen occurred around 1900. Analysis of Landsat satellite images, morphometric indicators characterizing the glacier frontal zones and previous studies indicate one surge of Hambergbreen (1957–1968) and five re-advances of Hornbreen in the 20th century (after 1936, between 1958 and 1962, in 1986–1990, 1998–1999, 2011). While the warmer Holocene intervals might be a benchmark for the effects of future climate change, glacier dynamics in post-Little Ice Age climate warming seems to be an analogue of glacier retreats and re-advances in the earlier periods of the Holocene.

Ancient Ice Reveals Scores of Gigantic Volcanic Eruptions

by C. Rotter, Mar 15, 2022 in WUWT/ClimPast


Magnitude, frequency and climate forcing of global volcanism during the last glacial period as seen in Greenland and Antarctic ice cores (60–9 ka)

Abstract

Large volcanic eruptions occurring in the last glacial period can be detected by their accompanying sulfuric acid deposition in continuous ice cores. Here we employ continuous sulfate and sulfur records from three Greenland and three Antarctic ice cores to estimate the emission strength, the frequency and the climatic forcing of large volcanic eruptions that occurred during the second half of the last glacial period and the early Holocene, 60–9 kyr before 2000 CE (b2k). Over most of the investigated interval the ice cores are synchronized, making it possible to distinguish large eruptions with a global sulfate distribution from eruptions detectable in one hemisphere only. Due to limited data resolution and large variability in the sulfate background signal, particularly in the Greenland glacial climate, we only list Greenland sulfate depositions larger than 20 kg km−2 and Antarctic sulfate depositions larger than 10 kg km−2. With those restrictions, we identify 1113 volcanic eruptions in Greenland and 737 eruptions in Antarctica within the 51 kyr period – for which the sulfate deposition of 85 eruptions is found at both poles (bipolar eruptions). Based on the ratio of Greenland and Antarctic sulfate deposition, we estimate the latitudinal band of the bipolar eruptions and assess their approximate climatic forcing based on established methods. A total of 25 of the identified bipolar eruptions are larger than any volcanic eruption occurring in the last 2500 years, and 69 eruptions are estimated to have larger sulfur emission strengths than the Tambora, Indonesia, eruption (1815 CE). Throughout the investigated period, the frequency of volcanic eruptions is rather constant and comparable to that of recent times. During the deglacial period (16–9 ka b2k), however, there is a notable increase in the frequency of volcanic events recorded in Greenland and an obvious increase in the fraction of very large eruptions. For Antarctica, the deglacial period cannot be distinguished from other periods. This confirms the suggestion that the isostatic unloading of the Northern Hemisphere (NH) ice sheets may be related to the enhanced NH volcanic activity. Our ice-core-based volcanic sulfate records provide the atmospheric sulfate burden and estimates of climate forcing for further research on climate impact and understanding the mechanism of the Earth system.How to cite. Lin, J., Svensson, A., Hvidberg, C. S., Lohmann, J., Kristiansen, S., Dahl-Jensen, D., Steffensen, J. P., Rasmussen, S. O., Cook, E., Kjær, H. A., Vinther, B. M., Fischer, H., Stocker, T., Sigl, M., Bigler, M., Severi, M., Traversi, R., and Mulvaney, R.: Magnitude, frequency and climate forcing of global volcanism during the last glacial period as seen in Greenland and Antarctic ice cores (60–9 ka), Clim. Past, 18, 485–506, https://doi.org/10.5194/cp-18-485-2022,

Ancient El Niños reveal limits to future climate projections

by University of Texas at Austin, Mar 15, 2022 in ScienceDaily


The climate pattern El Niño varies over time to such a degree that scientists will have difficulty detecting signs that it is getting stronger with global warming.

That’s the conclusion of a study led by scientists at The University of Texas at Austin that analyzed 9,000 years of Earth’s history. The scientists drew on climate data contained within ancient corals and used one of the world’s most powerful supercomputers to conduct their research.

The study of the past, which was recently published in Science Advances, was motivated by the need to get a clearer picture of how climate change may affect El Niño in the future.

El Niño is the warm phase of the El Niño Southern Oscillation, a climate phenomenon that sets the stage every few years for weather patterns worldwide. Strong El Niño events, such as the ones in 1997 and 2015 that brought wildfires to the rainforests of Borneo in Asia and caused widespread bleaching to the world’s coral reefs, happened about once a decade.

Computer models, however, are unclear about whether El Niño events will become weaker or stronger as the world warms due to climate change.

New Study Suggests The Early Holocene’s Baltic Sea Temperatures Were 5-11°C Warmer Than Present

by Weiss et al., 2022 in NoTricksZone


Baltic Sea surface temperatures may have reached 24°C 7,200 years ago compared to the current 12.7°C.

A new study (Weiss et al., 2022) indicates Baltic Sea regional surface temperatures ranged between 21-24°C from ~5.7 to 7.7 ka (thousand years ago). This period is referred to as the Baltic’s Holocene Thermal Maximum.

Temperatures dipped to 17.2°C at 1.373 ka. (The time span ranging from 0.0 ka to 3 ka is referred to in the study as the Modern Baltic, or M.B.)

The current (0.0 ka) surface temperature for the Baltic S is 12.7°C. This temperature is more than 11°C colder than the Baltic’s temperatures at 7.2 ka.

Climate Change in the Early Holocene

by University of Oxford, Jan 27, 2022 in WUWT

Radiocarbon dating from a prehistoric cemetery in Northern Russia reveals human stress caused by a global cooling event 8,200 years ago Early hunter gatherers developed more complex social systems and, unusually, a large cemetery when faced by climate

Peer-Reviewed Publication

 

16:00 (GMT), Thursday 27 January 2022

Climate change in the Early Holocene

  • Radiocarbon dating from a prehistoric cemetery in Northern Russia reveals human stress caused by a global cooling event 8,200 years ago
  • Early hunter gatherers developed more complex social systems and, unusually, a large cemetery when faced by climate change

New insight into how our early ancestors dealt with major shifts in climate is revealed in research,  published today [27 Jan] in Nature Ecology & Evolution, by an international team, led by Professor Rick Schulting from Oxford University’s School of Archaeology.

It reveals, new radiocarbon dates show the large Early Holocene cemetery of Yuzhniy Oleniy Ostrov, at Lake Onega, some 500 miles north of Moscow, previously thought to have been in use for many centuries, was, in fact, used for only one to two centuries. Moreover, this seems to be in response to a period of climate stress.

Sea Levels Near B.C. Canada Were 90 Meters Higher Than Today 14,500 Years Ago

by K. Richard, Aug 23, 2021 in NoTricksZone


A new study suggests British Columbia (Canada) relative sea levels remained 10 meters higher than they are today until they fell to their present levels in the last ~1800 years. Two other new studies suggest sea levels were still 0.8 to 1 meter higher than today during the Medieval Warm Period.

After the peak of the last glacial about 20,000 years ago, relative sea levels subsequently rose from 120 meters below modern sea levels to heights of 90 meters above today’s by ~14,500 years ago in the Douglas Channel near British Columbia, Canada (Letham et al., 2021).

Sea levels proceeded to fall 75 to 80 meters over the next 3000 years, or about -2.5 meters per century (-25 mm/yr), and then they remained 10-15 m above present for the next ~9000 years.

We determine that central Douglas Channel was ice-free following the Last Glacial Maximum by 14,500 BP and RSL was at least 90 m higher than today. Isostatic rebound caused RSL to fall to 21 m asl by 11,500 BP, though there may have been a glacial re-advance that would have paused RSL fall around the beginning of the Younger Dryas. RSL fell to 10–15 m asl by 10,000 BP, and continued to drop at a slower rate towards its current position, which it reached by ∼1800 years ago.”

Very Inconvenient Alps Glacier History…Top Glaciologists: Alps Were Ice-Free 6000 Years Ago

by C. Rotter, Jan 7, 2021 in WUWT


Alps ice-free…6000 years ago, when CO2 was much lower than today’s levels.

Dr. Sebastian Lüning earlier today released his latest Klimaschau report, No. 6. In the first part he looks at glaciers in the Alps over the course of much the Holocene.

See the video

It turns out that Most of the Alps were ice-free 6000 years ago, glaciologists have discovered.

In his video, the German geologist presents a new paper authored by glaciologists Bohleber et al, 2020 of the Austrian Academy of Science. The Austrian-Swiss team discovered from ice cores that the 3500-meter high Weißseespitze summit was ice free 5900 years ago.

Much warmer in the early Holocene

Lüning next shows why the Alps were ice-free 6000 years ago by using a chart by Heiri et al 2015, which shows it was some 2°C warmer than today.

Today’s Iceland Colder, Icier Than In Last 8,000 Years (Except the 1800s)

by K. Richard, Dec 15, 2020 in ClimateChange Dispatch


A wealth of new research in glacier and sea ice extent shows modern Iceland is 2-4°C colder than all of the last 8,000 years except for a slightly colder late 19th century.

Even the 1700s were warmer with less ice than today in and around Iceland.

A new study (Geirsdóttir et al., 2020) now affirms peak Holocene warmth at least “∼3–4 °C above modern in Iceland” prevailed throughout much of the last 8,000 years.

Data from tree growth, glacier-induced soil erosion, algae productivity, sea ice biomarker proxies (IP25), and other climate indices affirm these conclusions.

Harning et al., 2020 report an overall 7°C Holocene cooling trend In Iceland’s surrounding sea surface temperatures (SST).

“In terms of foraminifera-reconstructed SST, there is an overall trend of cooling throughout the last 8 ka from ~10 °C to ~3 °C.”

 

It is only in the last few centuries of the modern era that temperatures sharply plummeted to their lowest values of the last 10,000 years (Geirsdóttir et al., 2020).

“The coolest climate of the last 10 ka occurred in the late 1800s CE.”

Consequent to the peak cooling, glaciers and sea ice reached their maximum extents of the Holocene just 150 years ago.

While Iceland’s glaciers and North Shelf sea ice extent did partially recover in the first half of the 20th century, the ice extents are still beyond what they were in the 1700s and earlier.

There is nothing to indicate modern warmth or ice recession in and around Iceland is unprecedented or even unusual.

Read more at No Tricks Zone

New Paleoclimatology Finding Shows Earth’s Climate Was Typically Warmer than Today

by H.S. Sterling, Dec2, 2020 in WUWT


Archaeologists have published a new paper in The HoloceneDOI: 10.1177/0959683620972775 that confirms what previous research has shown: numerous periods during recent history have been as warm as or warmer than the present.

The press release was covered in The New Scientist, “Climate change has revealed a huge haul of ancient arrows in Norway,”  and discusses the findings of researchers from the Universities of Cambridge, Oslo, and Bergen. The researchers discovered a “treasure trove” of arrows, arrowheads, clothing, and other artifacts, recently uncovered by a receding ice in a mountainous region of southern Norway. The oldest arrows and artifacts date from around 4100 BC. The youngest artifacts date from approximately AD 1300, at the end of the Medieval Warm Period. Because present temperatures are only now exposing some of the artifacts were deposited when no ice covered the ground, temperatures were clearly warmer during the many periods when artifacts were deposited.

Along with the arrows and other artifacts, the researchers found nearly 300 specimens of reindeer antler and bone exposed by receding ice. Because reindeer presently frequent the area, the archaeologists say they are confident the area has served as an important hunting ground, off and on, for millennia.

The fact that artifacts were found from several different periods separated by hundreds and thousands of years in time indicates the ice and snow in the region has expanded and receded several times over the current interglacial period.

Elsewhere in Norway, scientists also recently uncovered what they have labeled a “Viking highway,” a route the ancient peoples inhabiting the region used to travel regularly. The route had for approximately 2,000 years been covered by snow and ice that expanded as the region’s climate shifted from a relatively warm period, comparable to present temperatures, to a colder period during which “permanent” thick snow and ice cover formed. This erected the equivalent of a “highway closed” sign.

How ancient dust from the sea floor helps to explain climate history

by UNIVERSITY OF OLDENBURG, Nov 11, 2020 in WUWT


During the last Ice Age about 20,000 years ago, iron-containing dust acted as a fertilizer for marine phytoplankton in the South Pacific, promoting CO2 sequestration and thus the glacial cooling of the Earth. But where did the dust come from? Researchers led by Dr. Torben Struve, geoscientist at the University of Oldenburg, Germany, have investigated this open question of climate history, which is also relevant with respect to current climate change.

Using sediment cores from the sea floor, they found that a large part of the dust deposited in the southern South Pacific at that time had travelled an extremely long way. Up to 80 percent of the dust came from what is now north-west Argentina, from where it was transported almost completely around the globe by the prevailing westerly winds. After a voyage of up to 20,000 kilometres, it contributed significantly to the increased input of iron into the glacial South Pacific. The dust input from Australia, which dominates in the South Pacific today, played only a minor role. The research team has published these new insights into the mechanisms of natural iron input into the Southern Ocean in the journal Nature Communications.

“We have analysed the chemical fingerprint of the dust and compared it with geological data from several continents. This was laborious work, like a jigsaw puzzle,” says Struve, a post-doctoral scientist in the research group “Marine Isotope Geochemistry” at the University’s Institute for Chemistry and Biology of the Marine Environment (ICBM). The team included researchers from his group as well as colleagues from the Alfred Wegener Institute – Helmholtz Centre for Polar and Marine Research, Bremerhaven (Germany), and from Columbia University, New York (USA).

3 More New Studies Show Modern Arctic Sea Ice Extent Is Greater Than Nearly Any Time In The Last 10,000 Years

by K. Richard, Oct 29, 2029 in NoTricksZone


For years scientists have been using biomarker evidence (IP25, PIP25) to reconstruct the Arctic’s sea ice history. The evidence shows modern (20th-21st century) Arctic sea ice is at its greatest extent since the Holocene began.

Scientists (Wu et al., 2020) have determined that from about 14,000 to 8,000 years ago, when CO2 lingered near 250 ppm, the Beaufort Sea (Arctic) was “nearly ice free throughout the year” (<0.2 PIP25) and ~4°C warmer than today in winter.

With CO2 at ~400 ppm, this region is 70-100% ice-covered (>0.8 PIP25) for all but 1-2 summer months in the modern (1988-2007) era.

….

“Where’s the sea ice?” Right where it’s been for most of the Holocene.

by D. Middleton, Oct 30, 2020 in WUWT


This is sort of a sequel yesterday’s post: Where’s the sea ice? 3 reasons the Arctic freeze is unseasonably late and why it matters.

What a difference a day can make! Looks like it’s starting to crust over:

Figure 0. Daily sea ice extent map, October 29, 2020. (NSIDC)

Two key takeaways:

  1. Maximum Holocene sea ice extent occurred within the past 500-1,000 years at every location.
  2. The current sea ice extent is higher at all of the locations than over 50% to 85% of the Holocene.

While this doesn’t tell us what the sea ice extent was in million km2, it does tell us that the modern sea ice extent is larger than it was over most of the Holocene Epoch. It also tells us that the areas of currently seasonal sea ice extent have been seasonal or reduced over most of the past 5,000 years and ice-free or nearly ice-free over the prior 3,000 years or so. Here’s is the Kinnard graph plotted at the same horizontal scale as the Stein cross section:

A Geological Perspective of Polar Bears

by D. Middelton, Oct 11, 2020 in WUWT


Estimates have ranged from 70,000 to 5,000,000 years ago. The oldest confirmed polar bear fossil dates to 110,000 to 130,000 years ago… Meaning that polar bears survived the Eemian interglacial stage.

The peak warmth of the Eemian interglacial stage marks the boundary between the Late Pleistocene Tarantian Age and the Middle Pleistocene Ionian Age.

Que nous apprend l’Optimum Climatique Romain?

by A. Préat, 4 septembre 2020 in ScienceClimatEnergie


1/ Introduction

SCE a plusieurs fois rapporté que la période actuelle de réchauffement n’est pas exceptionnelle, qu’elle fait partie de cycles décennaux à pluriséculaires de refroidissement et réchauffement qui ont lieu dans des fourchettes de température fort modestes, de l’ordre de 0,15°C par 10 ans. SCE a aussi montré que le CO2 tant incriminé dans ces changements, et surtout l’actuel, n’avait pas de raison d’être, ce gaz venant après l’augmentation de température. Le ‘bouton CO2 ‘ à même d’expliquer ou de ‘justifier’ le battage médiatique quasi-quotidien est donc à ‘la remorque’ de la température et, l’hypothèse de l’effet de serre reste avant tout une hypothèse (exemple ici).

Mercury Deposition, Climate Change and Anthropogenic Activities: A Review

by Li, F. et al. July 31, 2020 in Front. Earth.Sci.


As a toxic and harmful global pollutant, mercury enters the environment through natural sources, and human activities. Based on large numbers of previous studies, this paper summarized the characteristics of mercury deposition and the impacts of climate change and human activities on mercury deposition from a global perspective. The results indicated that global mercury deposition changed synchronously, with more accumulation during the glacial period and less accumulation during the interglacial period. Mercury deposition fluctuated greatly during the Early Holocene but was stable and low during the Mid-Holocene. During the Late Holocene, mercury deposition reached the highest value. An increase in precipitation promotes a rise in forest litterfall Hg deposition. Nevertheless, there is a paucity of research on the mechanisms of mercury deposition affected by long-term humidity changes. Mercury accumulation was relatively low before the Industrial Revolution ca. 1840, while after industrialization, intensive industrial activities produced large amounts of anthropogenic mercury emissions and the accumulation increased rapidly. Since the 1970s, the center of global mercury production has gradually shifted from Europe and North America to Asia. On the scale of hundreds of thousands of years, mercury accumulation was greater in cold periods and less in warm periods, reflecting exogenous dust inputs. On millennial timescales, the correspondence between mercury deposition and temperature is less significant, as the former is more closely related to volcanic eruption and human activities. However, there remains significant uncertainties such as non-uniform distribution of research sites, lack of mercury deposition reconstruction with a long timescale and sub-century resolution, and the unclear relationship between precipitation change and mercury accumulation.

Extensive hake (fish) skeletal remains in ocean waters too cold for this species to occupy today suggest past ocean temperatures were several degrees warmer.

by Wheeland & Morgan, July 2020 in NoTricksZone


Fish habitats are limited by specific temperature boundaries. In a new study, for example,  Wheeland  and Morgan (2020) found there was a pronounced ocean warming from the 1980s to late 1990s off the coasts of Greenland. This temperature shift changed the distribution of halibut habitat. Since then, however, there has been no net warming in the study region (through 2016).

New Study: Arctic Waters Were 4°C Warmer Than Today And Nearly Sea-Ice Free Year-Round ~4100 Years Ago

by Brice et al., May 28, 2020 in NoTricksZone


Today, the region north of Svalbard is encrusted with sea ice for all but a few weeks per year and summer sea surface temperatures (SSTs) hover near 0°C.  Scientists (Brice et al., 2020) have determined this same region had sea ice-free conditions last about 10 months per year while SSTs reached 4°C just ~4100 years ago.

In early September, 2019, Arctic explorers once again needed to be rescued from the “disappearing” sea ice that had captured their ship in central Svalbard. This region is presently free of sea ice for only a few weeks per year (late August).

Image Source: electroverse.net

Study: Ancient ocean oxygen levels associated with changing atmospheric carbon dioxide


by Texas A&M University, May 24, 2020 in WUWT


A Texas A&M-led study analyzed ocean floor sediment cores to provide new insights into the relationship between deep ocean oxygenation and atmospheric carbon dioxide levels in the 50,000 years before the last ice age

IMAGE: Deep ocean floor sediment cores hold chemical clues to Earth’s past. view more  Credit: Texas A&M University

Why do carbon dioxide levels in the atmosphere wax and wane in conjunction with the warm and cold periods of Earth’s past? Scientists have been trying to answer this question for many years, and thanks to chemical clues left in sediment cores extracted from deep in the ocean floor, they are starting to put together the pieces of that puzzle.

Recent research suggests that there was enhanced storage of respired carbon in the deep ocean when levels of atmospheric carbon dioxide concentrations were lower than today’s levels. But new research led by a Texas A&M University scientist has reached back even further, for the first time revealing insights into atmospheric carbon dioxide levels in the 50,000 years before the last ice age.

New Study: Greenland Was ‘4–5 °C Warmer Than Today’ ~9000 Years Ago…When The Arctic Was Nearly Sea-Ice Free

by Syring et al., February 6, 2020 in NoTricksZone


Scientists (Syring et al., 2020) find almost sea ice-free conditions pervaded a much warmer northern Greenland region during the Early Holocene.  Arctic sea ice extent has “continuously” grown for ~4800 years, with modern conditions a bit lower than the peak of the last few centuries.

 

In a new paper (Syring et al., 2020), scientists rely on biomarker evidence – (a) the presence of warmth-demanding species Armeria scabra and Mytilus edulis, and (b) IP25, a proxy for the presence or absence of sea ice – to suggest not only were there much warmer (4 to 5°C) northern Greenland temperatures 10,000 to 8500 years ago, but effectively sea ice-free conditions pervaded the region during this time.

The sea ice in the region has been growing “continuously” for the last 4800 years, reaching its peak during the last millennium.

The authors also find decadal- and centennial-scale periodicities in solar activity have coincided with variability in Arctic sea ice (IP25) throughout the Holocene.

19 Papers Published In 2019 Affirm Sea Levels Were METERS Higher Than Today 4-8 Thousand Years Ago

by K. Richard, January 16, 2020 in NoTricksZone


The onslaught of paleoclimate evidence for warmer-than-now Mid-Holocene climates – when the Earth’s sea levels were meters higher than they are today –  stormed through 2019.

There were 107 scientific papers published this past year indicating today’s warmth isn’t even close to being unusual or unprecedented when compared to the climates of the last centuries to millennia.

As illustrated below, there were also 19 papers affirming today’s sea levels are among the lowest of the last ~8000 years.

This is added to the list of nearly 100 scientific papers published in the last handful of years indicating Mid-Holocene sea levels were multiple meters higher than they are today due to the much more extensive glacier and ice sheet melt occuring during these millennia.

YOUNGER DRYAS — REWIND AND REPEAT

by Poppaloff, January 10, 2020 in Electroverse


If the historical data is anything to go by, magnetic reversals/excursions often lead to large-level extinction events. Mounting evidence also suggests that our sun micro-novas every 12,000 years, or thereabouts, and that these two events are linked. Earth’s temperature has been on a downward trend since the sharp-warming that followed the end of the Younger Dryas, indicating that this coming Grand Solar Minimum could steer us back into a major glaciation period, and another extinction event.

In their 2014 paper, a group of scientists which included UC Santa Barbara’s James Kennett, posited that a comet collision with Earth played a major role in the extinction. Their hypothesis suggests that a cosmic-impact-event caused the Younger Dryas period of global cooling close to 12,800 years ago. This cosmic impact resulted in abrupt environmental stress and degradation that contributed to the extinction of most large animal species then inhabiting the Americas. According to Kennett, the catastrophic impact and the subsequent climate change also led to the disappearance of the prehistoric Clovis culture, known for its big game hunting, and to human population decline.

 

Early Holocene Temperature Oscillations Exceed Amplitude of Observed and Projected Warming in Svalbard Lakes

by Van der Bilt et al. , December 3, 2019 in GeophysResLetters


Abstract

Arctic climate is uniquely sensitive to ongoing warming. The feedbacks that drive this amplified response remain insufficiently quantified and misrepresented in model scenarios of future warming. Comparison with paleotemperature reconstructions from past warm intervals can help close this gap. The Early Holocene (11.7–8.2 ka BP) is an important target because Arctic temperatures were warmer than today. This study presents centennially resolved summer temperature reconstructions from three Svalbard lakes. We show that Early Holocene temperatures fluctuated between the coldest and warmest extremes of the past 12 ka, exceeding the range of instrumental observations and future projections. Peak warmth occurred ~10 ka BP, with temperatures 7 °C warmer than today due to high radiative forcing and intensified inflow of warm Atlantic waters. Between 9.5 and 8 ka BP, temperatures dropped in response to freshwater fluxes from melting ice. Facing similar mechanisms, our findings may provide insight into the near‐future response of Arctic climate.

8000 Years Of Zero Correlation Between CO2 And Temperature, GISP 2 Ice Core Shows – Opposite Is True!

by P. Gosselin, December 20, 2019 in NoTricksZone


A plot of ice core data from Greenland reveals that CO2 does not drive temperatures.

At Facebook, Gregory Wrightstone posted a chart plotting atmospheric CO2 concentration reconstructed from  Dome C Ice Core versus temperature that was reconstructed from the GISP 2 Ice Core.

According to global warming scientists, there’s supposed to be tandem movement between the two magnitudes.

CO2, they say, drives global temperature.

But over the past 8000 years, the data show that temperature in reality has moved in the opposite direction of CO2 and thus of what climate alarmist scientists have told us.

 

If anything can be drawn from the plotted data, it is that there’s an inverse correlation: As CO2 rises, temperature drops. But of course there’s a lot more to it. CO2 is not that huge major climate driver that alarmists like having us believe it is.

3000-Year-Old Trees Excavated Under Icelandic Glacier

by P. Homewood, December 12, 2019 in NotaLotofPeopleKnowThat


Ancient tree stumps found under Breiðamerkurjökull glacier in Southeast Iceland are confirmed to be roughly 3,000 years old. RÚV reports.

A specialist believes the remarkably well-preserved stumps were part of a massive forest that disappeared after a long period of a warm climate.

One of the tree stumps was found in Breiðamerkursandur a couple of months ago, and once it was being salvaged a second, larger one was found. The smaller one was sent for examination while the larger will be examined at a later time.

Examinations revealed that the tree stump died very quickly at 89-years-old in the month of June. Nearby sediments and data suggest that the glacier itself was the culprit.

The tree stumps are from a period when Iceland was covered in forests. Even though 9th century Norse settlers reported vast forests across the country, it is believed that 3,000 years ago, the forests were much larger, even reaching the highlands. Approximately 500 BC, the climate became colder and glaciers began to form, destroying parts of the forests.

The 3,000-year-old remains of the forest are very well preserved and will be researched thoroughly. “It is absolutely incredible just how well preserved this tree stump is, having been buried under a glacier and that it still looks so whole, as opposed to being all wrinkled up like many of the specimens we have found.” Once examinations conclude, the water will be extracted from the tree stump and it will be filled with wax instead, allowing it to be exhibited.

https://www.icelandreview.com/news/3000-year-old-trees-excavated-under-glacier/

Discovering ancient forests under receding glaciers is not confined to Iceland. Remains of trees dating back to the Middle Ages have been found under the Juneau and Exit Glaciers in Alaska, as well under glaciers in Patagonia.

Tree stumps have also turned up under Swiss glaciers, carbon dated to about 4000 years ago.

The simple reality is that glaciers worldwide expanded enormously during the Little Ice Age, arguably to their greatest extent since the Ice Age. Despite decades of retreat since the 19thC, they are still abnormally large by historical standards.