For decades, scientists have kept track of how climate change has affected the Arctic sea ice, and how these changes affect the entire planet. In a new study, researchers search for what triggered the Little Ice Age that affected Europe from the 1300s to the 1800s.
The team's publication in the journal Science Advances describes conditions causing sudden climate change occurring spontaneously without an external force. The Little Ice Age is not like the prehistoric Ice Age, but rather, cooling the climate in Europe over nearly 500 years.
Using climate models, European researchers reconstructed the Arctic sea ice for the past 1400 years. The models suggest that the Little Ice Age was triggered by the flow of sea ice from the Arctic Ocean into the Atlantic Ocean by the 1300s.
Geological Evidence & Climate Models
The team also looked for geological records to support the climate models for physical evidence. To confirm the large flow of sea ice during the Little Ice Age, the team looked at records from marine sediment cores drilled from the ocean floors of both oceans. Martin Miles of the NORCE Norwegian Research Centre and Bjerknes Centre for Climate Research shared that the team put together different strands of evidence to try to reconstruct what the sea ice was for the past 1,400 years.
What they found in the sediment cores were compounds made by algae that live in sea ice and debris. The tiny organisms can adapt to changing temperatures when the sea ice moved south into the North Atlantic.
The cores also contained evidence of how the sea ice and ocean conditions changed over time. At the beginning of the 1300s, records showed a sudden increase of Arctic sea ice flowing into the North Atlantic and ended just as suddenly before the 1400s. Miles shared his fascination with looking at the sea ice was an indicator of climate change and "how it interacts with or could actually lead to changes in the climate system on long timescales."
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Spontaneous Climate Change
For years, scientists have debated about what triggered the Little Ice Age, like suggesting that the cooling period was caused by volcanic eruptions. This is the first paper with evidence suggesting the role of Arctic sea ice affecting the climate in Europe during that time.
The climate models or control models they used showed the climate system over time without external factors such as greenhouse gas emissions. The models are also known as Ugly Duckling simulations since they seem unrealistic and extreme.
Miles explained otherwise, saying that they found physical and geological evidence that these several decade-long cold sea ice excursions in the same region can and do occur without external factors. Similar to an Ugly Duckling model simulation, the team's climate model involved unusual winds, sea ice export, and a lot more ice east of Greenland. Their findings also suggest that these spontaneous occurrences can suddenly and unexpectedly happen due to internal variability in the climate system.
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