- Sea ice can act as a weather reversal agent on various timescale and spatial scales – it’s not just a passive responder to change.
- Rather than reacting to external pressures from volcanic eruptions or other factors, internal ice variability within the climate system has led to a small ice age “out of the blue.”
- The distant pulse of sea ice may have contributed to the demise of the Norse settlements in Greenland in the 14th and 15th centuries.
A new study finds a trigger for the Little Ice Age that cooled Europe in the mid-1800s, and supports surprising model results that suggest that sudden changes in the atmosphere under appropriate conditions can occur spontaneously, without external pressure.
Study published in Progress in science, There have been reports of sea ice transport through Greenland and from the Arctic Ocean to Greenland and over the last 1400 years in the Atlantic Ocean. Reconstruction suggests that the Little Ice Age – which was not a true ice age but a regional cooling centered on Europe – began in the 1300s due to the exceptionally large flow of sea ice from the Arctic Ocean to the North Atlantic.
The map shows Greenland and adjacent ocean currents. Colored circles show that some of the silt core used in the study was obtained from seafloor. A small historical map from the early 20th century shows the distribution of stories or sea ice from the Arctic Ocean, which flows down the east coast of Greenland. Credit: Miles et al., 2020.
While previous experiments using statistical climate models Dello showed that it was necessary to increase sea ice to explain long-running climate anomalies such as the Little Ice Age, physical evidence is missing. This study model digs into the geological record to confirm the results.
Researchers simultaneously pulled records of corals drilled from the ocean floor to the sea floor from the Arctic Ocean to the North Atlantic to get a detailed look at sea ice in the area over the last 1400 years.
“We decided to try to reconstruct what sea ice was during the last two and a half thousand years and try to temporarily reconstruct it, and then look at what we found,” said Martin Miles, a researcher at INSTAR. Has an appointment with the Research Center and the Berkenes Center for Environmental Research in Norway.
These cores consist of compounds formed by algae that live in sea ice, shells of single-celled organisms that live at different water temperatures, and pick up debris or sea ice and carry it over long distances. The cores were detailed enough to detect sudden (deckdale scale) changes in sea ice and ocean conditions over time.
Records show that in the North Atlantic, beginning around 1300, there was a sudden increase in exports of Arctic sea ice, peaking in the middle of the year and ending abruptly in the late 1300s.
Shows the reconstruction time range of changes in the occurrence of sea ice and polar waters in the past. The color of the curve corresponds to the locations on the map. Blue shading represents an increased period of sea ice in the 1300s. Credit: Miles et al., 2020.
“I don’t always see sea ice as a passive indicator of climate change, but I’m always fascinated by how it can change the climate system over a long period of time or how it really interacts with it,” Miles said. “And the perfect example might be the Little Ice Age.”
“This special investigation was inspired by some paleoclimate reconstructions by INSTAAR colleagues Giff Miller, as well as my INSTAAR colleagues Anne Jennings, John Andrews, and Astrid Ogilvy,” Miles added. Miller wrote on the first paper that sea ice would play an important role in sustaining a small ice age.
While many scientists have argued for decades about the causes of the Little Ice Age, many suggest that an erupting volcanic eruption must be necessary to initiate a period of cooling and allow it to continue for centuries. On the one hand, the new reconstruction provides strong evidence of sea-ice anomalies that can be caused by increasing volcanic eruptions. The same evidence, on the other hand, supports an interesting alternative explanation.
Instar Research Associate Martin Miles in the modern subarctic fjord setting. Credit: Martin Miles
Climate models known as “control models dales” are run to understand how the weather system works, without being influenced by external forces such as dello, volcanic activity or greenhouse gas emissions. A set of recent control model experiments included results that illustrated sudden cold events that lasted for decades. The results seemed too extreme for Dell’s results to look real – so-called ugly duckling simulations – and the researchers were concerned that they might show a problem in the models.
Miles ’study found that there could be nothing wrong with those models.
“We’ve really found that number one, we have physical, geological evidence that this many decades-long cold sea ice trip in the same region could, in fact, happen,” he said. In the case of the Little Ice Age, “what we rebuilt in space and time was similar to the development of the ugly duckling model simulation, in which a spontaneous freezing event lasted for almost a century. These included unusual winds, sea ice exports, and much more snow east of Greenland, as we found here. “Provocative results show that external pressure from volcanoes or other causes may not be necessary for large swings in the weather. Miles continues,” These results strongly suggest that રંગ may come out of the blue due to internal variability in the climate system. “
The Marine Corps also shows the continuous and distant pulse of sea ice near the Norse Coalition in Greenland coincidentally with their disappearance in the 15th century. The debate over why the settlements disappeared has sparked controversy, generally simply agreeing that the cold weather puts a strong strain on their resilience. Miles and his allies want to bring marine change closer: very large amounts of sea ice and cold polar water, for a century years later.
“This vast expanse of ice that comes out of the Arctic – in the past and even today – goes around Cape Farewell where these settlements used to be,” Mice said. He would like to take a closer look at marine conditions with researchers studying the social sciences in relation to climate.
Reference: Martin W. Miles, Camilla S. Anderson and Christian V. By Dilmer, 16 September 2020 “Evidence for the extreme export of Arctic sea ice that leads to the accidental beginning of the Little Ice Age”. Science progress.
DII: 10.1126 / sciadv.aba4320
Camilla S. of the Geological Survey of Denmark and Greenland. Anderson and Christian V. of MMT Sweden AB. Dilmer was a co-author of this study.
