New study may solve long-standing mystery of what triggered ice age

Canadian Arctic archipelago [via Wikipedia]

The clue is in the study title: The importance of Canadian Arctic Archipelago gateways for glacial expansion in Scandinavia.
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A new study led by University of Arizona researchers may have solved two mysteries that have long puzzled paleo-climate experts (says Phys.org): Where did the ice sheets that rang in the last ice age more than 100,000 years ago come from, and how could they grow so quickly?

Understanding what drives Earth’s glacial–interglacial cycles—the periodic advance and retreat of ice sheets in the Northern Hemisphere—is no easy feat, and researchers have devoted substantial effort to explaining the expansion and shrinking of large ice masses over thousands of years.

The new study, published in the journal Nature Geoscience, proposes an explanation for the rapid expansion of the ice sheets that covered much of the Northern Hemisphere during the most recent ice age, and the findings could also apply to other glacial periods throughout Earth’s history.

Clouds played an important role in the history of climate, say researchers

Cumuliform cloudscape over Swifts Creek, Australia
[image credit: Wikipedia]

Looking into the past and future of climatic conditions on computer models can give somewhat cloudy results, at least partly because “there’s considerable uncertainty about the simulation of clouds in global climate models”.
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Were Earth’s oceans completely covered by ice during the Cryogenian period, about 700 million years ago, or was there an ice-free belt of open water around the equator where sponges and other forms of life could survive?

Using global climate models, a team of researchers from Karlsruhe Institute of Technology (KIT) and the University of Vienna has shown that a climate allowing a waterbelt is unlikely and thus cannot reliably explain the survival of life during the Cryogenian, says Phys.org.

The reason is the uncertain impact of clouds on the epoch’s climate.

Scientists shine new light on role of Earth’s orbit in the fate of ancient ice sheets

A reconstruction of the Anglian ice sheet in Precambrian North London (credit: BBC / The Natural History Museum, London)

They claim this solves the so-called 100,000 year problem described by Wikipedia:
‘The 100,000-year-problem refers to the lack of an obvious explanation for the periodicity of ice ages at roughly 100,000 years for the past million years, but not before, when the dominant periodicity corresponded to 41,000 years. The unexplained transition between the two periodicity regimes is known as the Mid-Pleistocene Transition, dated to some 800,000 years ago.’ [41,000 years being the approximate obliquity cycle period]
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In a new study published today in the journal Science, the team from Cardiff University has been able to pinpoint exactly how the tilting and wobbling of the Earth as it orbits around the Sun has influenced the melting of ice sheets in the Northern Hemisphere over the past 2 million years or so.

Scientists have long been aware that the waxing and waning of massive Northern Hemisphere ice sheets results from changes in the geometry of Earth’s orbit around the Sun, says Phys.org.

There are two aspects of the Earth’s geometry that can influence the melting of ice sheets: obliquity and precession.

Ancient ‘megafloods’ tilted the very direction of Earth’s crust, scientists find

Image credit: NASA

Ice age flooding, recreated in models.
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Earth’s last major ice age locked up gargantuan amounts of water in vast glaciers, says Science Alert.

Once they melted, it was a spectacle to behold as tremendous floods gouged channels into the face of the planet.

The remnants of one of the largest of these ancient deluges are still visible in eastern Washington, in an area now known as the Channeled Scablands.

For a long time, geologists have been struggling to understand the dynamic properties of these floods, until a recent key insight was made.

These ancient glaciers were so large and heavy, they actually tilted Earth’s crust beneath them – when weight was released due to melting, the land would have moved too, changing the course of the megaflood.

Using modeling of ancient megafloods, researchers decided to test whether glacial isostatic adjustment (GIA) – deflections in the crust as heavy chunks of ice form and melt – would affect the routing flow and erosion in two prominent Scabland tracks.

“We used relatively simple, yet plausible, numerical experiments to test whether GIA could have had a substantial impact on flood routing and erosion for two major scabland tracts, Cheney-Palouse and Telford-Crab Creek,” write the authors of the study.

“To this end, we modeled GIA to reconstruct the topography of the Channeled Scabland at different times during the period of Ice Age flooding.”

Up until now, reconstructions of ancient megaflood routing had investigated how other variables would affect them – things like erosion and the movement of sediment, the three-dimensional mechanics of the environment, or how ice dams break, for example.

But they would also base these reconstructions on present-day topography, approximating how past landscapes may have looked.

“People have been looking at high water marks and trying to reconstruct the size of these floods, but all of the estimates are based on looking at the present-day topography,” said lead author Tamara Pico, assistant professor of Earth and planetary sciences at UC Santa Cruz.

Geologists realized that the effects melting glaciers were having on Earth’s crust were also likely playing a role in the routing and behavior of these megafloods.

“GIA caused crustal deformation in the Channeled Scabland with rates up to 10 millimeters per year, orders of magnitude above regional tectonic uplift rates and, therefore, may have influenced flood routing,” note the authors.

“The course of ancient, glacial outburst floods was likely influenced by glacial isostatic adjustment (GIA), and reconstructing these events informs our understanding of how floods shape landscapes on Earth and Mars,” they added.
. . .
The researchers believe the deformation of Earth’s crust due to the expanding and contacting of the ice sheets would have altered the elevation of the landscape by hundreds of meters over this period.

Moving forward, the researchers want to simulate past megaflood events which incorporate the multiple factors that determine their routing.

However, understanding the important role that ice age crustal deformation plays during flood routing and erosion in these ancient megafloods is a step in the right direction.

Full article here.

Ned Nikolov: Dispelling the Milankovitch Myth

Ned Nikolov, Ph.D.
Dec 30, 2021

There has been a long-standing belief in Paleoclimatology that orbital variations (a.k.a. Milankovitch cycles) have been responsible for the initiation and/or duration of glacial cycles (Ice Ages) over the past 800 Ky. Milankovitch cycles are often referred to as a pacemaker of the Ice Ages. This myth dates back to 1970s, when sediment cores revealed a weak correlation in the frequency domain between Earth’s 41-ky obliquity (axial-tilt) cycle and the periodicity of Ice Ages during the early Pleistocene (Quaternary). However, in the late Pleistocene, the frequency of glacial cycles better match the Earth’s 100-ky eccentricity cycle, which further fueled the confusion. Yet, no one has been able to demonstrate a meaningful relationship between glacial cycles and any of the Earth’s 3 orbital parameters obliquity, eccentricity and precession or combination thereof on a linear time scale. A physical causation requires a strong correlation between parameters in the time domain, not the frequency domain!

Quest begins to drill Antarctica’s oldest ice – again

Ice core sample [image credit: Discovering Antarctica]

Previous studies indicated temperature change preceded CO2 change, but the BBC says they occurred ‘in parallel’ or ‘in lockstep’, obscuring the key role of insolation while waffling about supposedly ‘heat trapping’ gases.
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Efforts are about to get under way to drill a core of ice in Antarctica that contains a record of Earth’s climate stretching back 1.5 million years, says BBC News.

A European team will set up its equipment at one of the highest locations on the White Continent, for an operation likely to take four years.

The project aims to recover a near-3km-long cylinder of frozen material.

Scientists hope this ice can help them explain why Earth’s ice ages flipped in frequency in the deep past.

Orbital resonance and the celestial origins of Earth’s climatic changes – Why Phi?

A year after I wrote the original ‘Why Phi’ post explaining my discovery of the Fibonacci sequence links between solar system orbits and planetary synodic periods here at the Talkshop in 2013, my time and effort got diverted into politics. The majority of ongoing research into this important topic has been furthered by my co-blogger Stuart ‘Oldbrew’ Graham. Over the last eight years he has published many articles here using the ‘Why Phi’ tag looking at various subsystems of planetary and solar interaction periodicities, resonances, and their relationships with well known climatic periodicities such as the De Vries, Hallstatt, Hale and Jose cycles, as well as exoplanetary systems exhibiting the same Fibonacci-resonant arrangements.

Recently, Stuart contacted me with news of a major breakthrough in his investigations. In the space of a few hours spent making his calculator hot, major pieces of the giant jigsaw had all come together and brought ‘the big picture’ into focus. In fact, so much progress has been made that we’re not going to try to put it all into a single post. Instead, we’ll provide an overview here, and follow it up with further articles getting into greater detail.

Abrupt ice age climate changes behaved like cascading dominoes

Rinks Glacier, West Greenland [image credit: NSIDC]

Interesting, but as we’ve had a temperature rise of about 1.2ºC since 1880, according to one source at least, comparisons with much bigger historical increases in shorter timescales seem somewhat ambitious, to say the least.
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Throughout the last ice age, the climate changed repeatedly and rapidly during so-called Dansgaard-Oeschger events, where Greenland temperatures rose between 5 and 16 degrees Celsius in decades, says Phys.org.

When certain parts of the climate system changed, other parts of the climate system followed like a series of dominos toppling in succession.

This is the conclusion from an analysis of ice-core data by a group of researchers that included postdoc Emilie Capron and associate professor Sune Olander Rasmussen from the Section for the Physics of Ice, Climate and Earth at the Niels Bohr Institute, University of Copenhagen, in Denmark.

This discovery, just published in the journal Nature Communications, is concerning because the extent of sea ice in the Arctic played an important part in these dramatic climate shifts of the past.

Ice Age Testing Reveals Challenges in Climate Model Sensitivity

Cloud formation [image credit:NASA]

‘Challenges’ is a polite way of putting it. Is the alleged human-caused climate problem really more of a human-caused climate models problem?
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Increased reflection of incoming sunlight by clouds led one current-generation climate model to predict unrealistically cold temperatures during the last ice age [Source: Geophysical Research Letters].

Key to the usefulness of climate models as tools for both scientists and policymakers is the models’ ability to connect changes in atmospheric greenhouse gas levels to corresponding shifts in temperature, says Eos.

Unmatched dust storms raged over Western Europe during Ice age maximum

Image credit: ScienceDaily

This has echoes of the ice age dust/albedo theory – with no CO2 feedbacks – proposed by Ralph Ellis a few years ago. The article concludes: ‘The result thus has the potential to aid the understanding of the abrupt warming and cooling periods during the ice ages called Dansgaard/Oeschger events which bear the marks of climate tipping points.’
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Every late winter and early spring, huge dust storms swirled across the bare and frozen landscapes of Europe during the coldest periods of the latest ice age, says Phys.org.

These paleo-tempests, which are seldom matched in our modern climate frequently covered Western Europe in some of the thickest layers of ice-age dust found anywhere previously on Earth.

This is demonstrated by a series of new estimates of the sedimentation and accumulation rates of European loess layers obtained by Senior Research Scientist Denis-Didier Rousseau from Ecole Normale Supérieure in Paris, France, and colleagues.

The work, which is published in Quaternary Science Reviews is part of the TiPES project on tipping points in the Earth system, coordinated by The University of Copenhagen.

In the study Denis-Didier Rousseau and colleagues reinterpreted layers in loess from Nussloch, Germany.

Loess is a fine-silt-sized earth type found all over the world. It mainly consists of aeolian sediments, which are materials transported by the wind from dry areas without vegetation such as deserts of any type, moraines, or dried-out river beds.

Within the aeolian sediments, darker layers of paleosol alternate within the loess layers. Every layer in the loess represents a shift in climatic conditions.

How cold was the ice age? Researchers now know – but blame ‘carbon’

Ice core sample [image credit: Discovering Antarctica]

But they ignore the fact that historical changes in carbon dioxide levels always followed changes in temperatures, so could not be the cause of such changes. The article below asserts the opposite, and talks about ‘better understanding’ while promoting a greenhouse climate theory that says one minor trace gas is all that matters.
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A University of Arizona-led team has nailed down the temperature of the last ice age—the Last Glacial Maximum of 20,000 years ago—to about 46 degrees Fahrenheit (7.8 C), says Phys.org.

Their findings allow climate scientists to better understand the relationship between today’s rising levels of atmospheric carbon dioxide—a major greenhouse gas—and average global temperature.

The Last Glacial Maximum, or LGM, was a frigid period when huge glaciers covered about half of North America, Europe and South America and many parts of Asia, while flora and fauna that were adapted to the cold thrived.

“We have a lot of data about this time period because it has been studied for so long,” said Jessica Tierney, associate professor in the UArizona Department of Geosciences. “But one question science has long wanted answers to is simple: How cold was the ice age?”

What causes an ice age to end?

Greenland ice sheet (east coast) [image credit: Hannes Grobe @ Wikipedia]

Of course the other question about the start of an ice age still remains.

New University of Melbourne research has revealed that ice ages over the last million years ended when the tilt angle of the Earth’s axis was approaching higher values, reports Phys.org.

During these times, longer and stronger summers melted the large Northern Hemisphere ice sheets, propelling the Earth’s climate into a warm ‘interglacial’ state, like the one we’ve experienced over the last 11,000 years.

The study by Ph.D. candidate, Petra Bajo, and colleagues also showed that summer energy levels at the time these ‘ice-age terminations’ were triggered controlled how long it took for the ice sheets to collapse, with higher energy levels producing fast collapse.

Researchers are still trying to understand how often these periods happen and how soon we can expect another one.

‘Melting Greenland’ likely to add up to half an inch to global sea levels by 2098

image credit https://visitgreenland.com/

Mike Waite left the following comment over at Paul Homewood’s excellent not a lot of people know that blog yesterday:

There is an interesting paper by MacGuth et al (2013) which supports you :

From their summary:

-“We calculate the future sea-level rise contribution from the surface mass balance of all of

Greenland’s glaciers and ice caps (GICs, ca. 90 000 km2) using a simplified energy balance

model which is driven by three future climate scenarios from the regional climate models

HIRHAM5, RACMO2 and MAR. Glacier extent and surface elevation are modified during the

mass balance model runs according to a glacier retreat parameterization. Mass balance and glacier surface change are both calculated on a 250 m resolution digital elevation model yielding a high level of detail and ensuring that important feedback mechanisms are

considered. The mass loss of all GICs by 2098 is calculated to be

2016 +/- 129 Gt (HIRHAM5 forcing),

2584 +/-109 Gt (RACMO2)

and 3907+/- 108 Gt (MAR). This corresponds to a total contribution to sea-level rise of

5:8 +/- 0:4,

7:4 +/- 0:3

and 11:2 +/- 0:3 mm, respectively. “-

The future sea-level rise contribution of Greenland’s glaciers and ice caps

H Machguth1,2, P Rastner1, T Bolch1,3, N M¨olg1, L Sandberg Sørensen4,

G Aðalgeirsdottir5, J H van Angelen6, M R van den Broeke6 and

X Fettweis7

Online at stacks.iop.org/ERL/8/025005

Even if subsequent calculations modified these figures they are unlikely to be an order of magnitude higher and the sea level rise to 2098 calculated here is at most 11mm (not cm or feet or metres).

Can’t someone take these activists, sit them in a quet room and just read the literature to them since they seem incapable of such study themselves.

Earth’s oldest asteroid crater found in Australia

Credit: earth.com

Theories abound, but the inevitable carbon dioxide one pops up at the end.

Scientists have identified the world’s oldest asteroid crater in Australia, adding it may explain how the planet was lifted from an ice age, reports BBC News.

The asteroid hit Yarrabubba in Western Australia about 2.2 billion years ago – making the crater about half the age of Earth, researchers say.

Their conclusion was reached by testing minerals found in rocks at the site.

The scientists say the find is exciting because it could account for a warming event during that era.

How did life survive in the Snowball Earth? Scientists might have cracked the mystery

The researchers do admit that ‘Snowball Earth is just a hypothesis’, but that period seems to have been an era of the most extreme long-term cold spell(s) ever detected on Earth.

There is very little life in Arctic tundras and glaciers. However that was the situation in a big portion of the world during Ice Ages, says Technology.org.

How did life survive these difficult periods? How didn’t everything just die, being cut off from any kind of sources of nutrition and oxygen?

Scientists examined the chemistry of the iron formations in Australia, Namibia, and California to get a window into the environmental conditions during the ice age. They selected rocks left there by the ice age, because they are representative of the conditions during that difficult period for life.

By analysing these rocks scientists from the McGill University were able to estimate the amount of oxygen in the oceans around 700 million years ago.

Changes in high-altitude winds over the South Pacific produce long-term effects

‘Long-term’ here means really long-term. The 21k year precession period quoted looks like that of the perihelion.

In the past million years, the high-altitude winds of the southern westerly wind belt, which spans nearly half the globe, didn’t behave as uniformly over the Southern Pacific as previously assumed.

Instead, they varied cyclically over periods of ca. 21,000 years, reports ScienceDaily.

A new study has now confirmed close ties between the climate of the mid and high latitudes and that of the tropics in the South Pacific, which has consequences for the carbon budget of the Pacific Southern Ocean and the stability of the West Antarctic Ice Sheet.

Ancient air challenges carbon dioxide explanation for a shift in glacial cycles

A reconstruction of the Anglian ice sheet in Precambrian North London (credit: BBC / The Natural History Museum, London)

This might rattle a few cages in climate-land.

An analysis of air up to 2 million years old, trapped in Antarctic ice, shows that a major shift in the periodicity of glacial cycles was probably not caused by a long-term decline in atmospheric levels of carbon dioxide, writes Eric W. Wolff in Nature.
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During the past 2.6 million years, Earth’s climate has alternated between warm periods known as interglacials, when conditions were similar to those of today, and cold glacials, when ice sheets spread across North America and northern Europe.

Before about 1 million years ago, the warm periods recurred every 40,000 years, but after that, the return period lengthened to an average of about 100,000 years.

It has often been suggested that a decline in the atmospheric concentration of carbon dioxide was responsible for this fundamental change.

Explosion in Antarctic sea ice levels may cause another ice age

Ross Ice Shelf, Antarctica

Is there an element of circular reasoning here? Carbon dioxide levels have historically followed temperature changes, bringing any supposed causation into question.

Upside-down “rivers” of warm ocean water may be one of the causes of Antarctica’s ice shelves breaking up, leading to a rise in sea levels.

But a new study suggests an increase in sea ice may lead to a much more devastating change in the Earth’s climate — another ice age, reports Fox News.

Using computer simulations, the research suggests that an increase in sea ice could significantly alter the circulation of the ocean, ultimately leading to a reverse greenhouse effect as carbon dioxide levels in the ocean increase and levels in the air decrease.

“One key question in the field is still what caused the Earth to periodically cycle in and out of ice ages,” University of Chicago professor and the study’s co-author, Malte Jansen, said in a statement. “We are pretty confident that the carbon balance between the atmosphere and ocean must have changed, but we don’t quite know how or why.”

Prof. Ian Plimer: Earth is ‘not in a period of extinction’

‘Belief is in politics and religion, not science…follow the money’, says Professor Plimer.

Geologist and earth scientist Ian Plimer says the globe is not facing a climate emergency, telling Sky News Australia that “we are actually still living in an ice age.”

Professor Plimer’s comments come after Extinction Rebellion protesters have been calling on the government to declare a climate emergency – something the scientist said isn’t necessary.

“We live in horribly boring times,” he said.

Scientists Drill For “Oldest Ice On Earth” To Unlock Mystery Of Ancient Earth’s Changing Climate

Credit: British Antarctic Survey

The EPICA ice cores clearly showed CO2 lagging behind temperature increases – probably by centuries. But observed effects aren’t supposed to precede alleged causes.

European scientists from 10 countries have spent years scouring the Antarctic ice sheet with one ambition in mind: to drill for the oldest-ever ice core.

Now, they have zeroed in on just the spot says IFL Science.

The team have chosen Little Dome C – one of the coldest, most barren places on Earth. For the next five years, they will drill for a 1.5-million-year-old ice core – a frozen timepiece of Earth’s climatic past.