Sea Ice Triggered the Little Ice Age

Related Articles

Related Articles

A new study finds a trigger for the Little Ice Age that cooled Europe from the 1300s through mid-1800s, and supports surprising model results suggesting that under the right conditions sudden climate changes can occur spontaneously, without external forcing.

The study, published in Science Advances, reports a comprehensive reconstruction of sea ice transported from the Arctic Ocean through the Fram Strait, by Greenland, and into the North Atlantic Ocean over the last 1400 years. The reconstruction suggests that the Little Ice Age–which was not a true ice age but a regional cooling centered on Europe–was triggered by an exceptionally large outflow of sea ice from the Arctic Ocean into the North Atlantic in the 1300s.

While previous experiments using numerical climate models showed that increased sea ice was necessary to explain long-lasting climate anomalies like the Little Ice Age, physical evidence was missing. This study digs into the geological record for confirmation of model results.

 

Researchers pulled together records from marine sediment cores drilled from the ocean floor from the Arctic Ocean to the North Atlantic to get a detailed look at sea ice throughout the region over the last 1400 years.

“We decided to put together different strands of evidence to try to reconstruct spatially and temporally what the sea ice was during the past one and a half thousand years, and then just see what we found,” said Martin Miles, an INSTAAR researcher who also holds an appointment with NORCE Norwegian Research Centre and Bjerknes Centre for Climate Research in Norway.

The cores included compounds produced by algae that live in sea ice, the shells of single-celled organisms that live in different water temperatures, and debris that sea ice picks up and transports over long distances. The cores were detailed enough to detect abrupt (decadal scale) changes in sea ice and ocean conditions over time.

The records indicate an abrupt increase in Arctic sea ice exported to the North Atlantic starting around 1300, peaking in midcentury, and ending abruptly in the late 1300s.

“I’ve always been fascinated by not just looking at sea ice as a passive indicator of climate change, but how it interacts with or could actually lead to changes in the climate system on long timescales,” said Miles. “And the perfect example of that could be the Little Ice Age.”

“This specific investigation was inspired by an INSTAAR colleague, Giff Miller, as well as by some of the paleoclimate reconstructions of my INSTAAR colleagues Anne Jennings, John Andrews, and Astrid Ogilvie,” added Miles. Miller authored the first paper to suggest that sea ice played an essential role in sustaining the Little Ice Age.

Scientists have argued about the causes of the Little Ice Age for decades, with many suggesting that explosive volcanic eruptions must be essential for initiating the cooling period and allowing it to persist over centuries. One the hand, the new reconstruction provides robust evidence of a massive sea-ice anomaly that could have been triggered by increased explosive volcanism. One the other hand, the same evidence supports an intriguing alternate explanation.

Climate models called “control models” are run to understand how the climate system works through time without being influenced by outside forces like volcanic activity or greenhouse gas emissions. A set of recent control model experiments included results that portrayed sudden cold events that lasted several decades. The model results seemed too extreme to be realistic–so-called Ugly Duckling simulations–and researchers were concerned that they were showing problems with the models.

Miles’ study found that there may be nothing wrong with those models at all.

“We actually find that number one, we do have physical, geological evidence that these several decade-long cold sea ice excursions in the same region can, in fact do, occur,” he said. In the case of the Little Ice Age, “what we reconstructed in space and time was strikingly similar to the development in an Ugly Duckling model simulation, in which a spontaneous cold event lasted about a century. It involved unusual winds, sea ice export, and a lot more ice east of Greenland, just as we found in here.” The provocative results show that external forcing from volcanoes or other causes may not be necessary for large swings in climate to occur. Miles continued, “These results strongly suggest…that these things can occur out of the blue due to internal variability in the climate system.”

The marine cores also show a sustained, far-flung pulse of sea ice near the Norse colonies on Greenland coincident with their disappearance in the 15th century. A debate has raged over why the colonies vanished, usually agreeing only that a cooling climate pushed hard on their resilience. Miles and his colleagues would like to factor in the oceanic changes nearby: very large amounts of sea ice and cold polar waters, year after year for nearly a century.

“This massive belt of ice that comes streaming out of the Arctic–in the past and even today–goes all the way around Cape Farewell to around where these colonies were,” Miles said. He would like to look more closely into oceanic conditions along with researchers who study the social sciences in relation to climate.

UNIVERSITY OF COLORADO AT BOULDER

Header Image Credit – Public Domain

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Camulodunum – The First Capital of Britannia

Camulodunum was a Roman city and the first capital of the Roman province of Britannia, in what is now the present-day city of Colchester in Essex, England.

African Crocodiles Lived in Spain Six Million Years Ago

Millions of years ago, several species of crocodiles of different genera and characteristics inhabited Europe and sometimes even coexisted.

Bat-Winged Dinosaurs That Could Glide

Despite having bat-like wings, two small dinosaurs, Yi and Ambopteryx, struggled to fly, only managing to glide clumsily between the trees where they lived, according to a new study led by an international team of researchers, including McGill University Professor Hans Larsson.

Ancient Maya Built Sophisticated Water Filters

Ancient Maya in the once-bustling city of Tikal built sophisticated water filters using natural materials they imported from miles away, according to the University of Cincinnati.

New Clues Revealed About Clovis People

There is much debate surrounding the age of the Clovis - a prehistoric culture named for stone tools found near Clovis, New Mexico in the early 1930s - who once occupied North America during the end of the last Ice Age.

Cognitive Elements of Language Have Existed for 40 Million Years

Humans are not the only beings that can identify rules in complex language-like constructions - monkeys and great apes can do so, too, a study at the University of Zurich has shown.

Bronze Age Herders Were Less Mobile Than Previously Thought

Bronze Age pastoralists in what is now southern Russia apparently covered shorter distances than previously thought.

Legio IX Hispana – The Lost Roman Legion

One of the most debated mysteries from the Roman period involves the disappearance of the Legio IX Hispana, a legion of the Imperial Roman Army that supposedly vanished sometime after AD 120.

Popular stories

Legio IX Hispana – The Lost Roman Legion

One of the most debated mysteries from the Roman period involves the disappearance of the Legio IX Hispana, a legion of the Imperial Roman Army that supposedly vanished sometime after AD 120.

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.