More than 100,000 years ago, global temperatures soared and the Arctic ice melted to plunge Europe into a deep freeze, a new study has indicated.
The research, from the iC3 Polar Research Hub, showed that in the Last Interglacial period, a warming world changed crucial ocean currents and meant that Europe cooled rapidly.
However, the lead author behind the study has told Yahoo News that events 128,000 years ago have a clear – and concerning – parallel to the threat posed by climate change today.
Mohamed Ezat, a scientist at The Arctic University of Norway’s iC3 Polar Research Hub, said that a repeat of the situation could have a drastic impact on the climate in Britain and Europe.
“The time period we investigated, the Last Interglacial, is an interesting and very timely period to study because the global temperatures during that time were about one to two degrees Celsius higher than pre-industrial – today we are already 1C degree higher than pre-industrial.
“In this sense, it provides some kind of analogue to what we are heading towards the end of this century.”
The researchers warn that with Arctic ice set to disappear by 2050, our current warming period could also trigger rapid temperature change in Europe.
It follows other studies in recent years that have suggested temperatures in Europe could rapidly drop by 10 degrees if one ocean current, the Atlantic Meridional Overturning Circulation (AMOC), collapses and stops delivering warm water to Europe.
What did the research find?
The researchers analysed sediment from ‘cores’ taken from the Nordic Seas to understand conditions in the Last Interglacial period, between 130,000 and 115,000 years ago. Using biological, inorganic and organic geochemical tracers, the team were able to reconstruct how freshwater and seawater were circulated.
Ezat explained: “These sediment cores act like time capsules, preserving information about past ocean conditions.
“We found that about 128,000 years ago, enhanced melting of Arctic sea ice had a significant effect on the overturning circulation in the Nordic seas, which is an important component of the Atlantic Ocean circulation and climate.
“The freshwater from the ice melt ran into the Nordic seas and North Atlantic, which resulted in altering ocean density that eventually led to a reduction in the northward ocean heat by the Atlantic currents. In the early part of the Last Interglacial, over 100,000 years ago, global temperatures were warmer than present, ice volumes were smaller, and sea levels were significantly higher.”
The researchers found that this disrupted ocean currents, and warn that it could have parallels in our situation today.
Ezat said: “One clear reason for being worried is that we learned from looking at past climate change, including my recent study, that the AMOC could change dramatically on human-relevant time scales. And we know that a collapse or weakening of this system could result in major cooling in Northern Europe.”
What is happening to Arctic sea ice?
In the same way, as Arctic sea ice thinned over 100,000 years ago, Arctic ice is melting rapidly today.
Simulations by the European Space Agency’s Climate Change Initiative suggest that the Arctic will be ice-free by 2050.
The last 18 years have seen the lowest 18 Arctic sea ice extents since records began. Research by America’s National Snow and Ice Data Center this year found this year’s ice is the seventh-lowest in 46 years.
“Every year brings something new for the Arctic Ocean,” NSIDC senior research scientist Walt Meier said this year.
“This summer we saw very early ice loss in Hudson Bay, open water near the North Pole and a stubborn ice floe near the Bering Strait that persisted through the summer melt season. While it wasn’t a new record low, this year’s sea ice minimum is yet another example of a changed Arctic environment.”
What could happen to the AMOC and why does it matter?
If the AMOC abruptly stopped, as the ice cores from 100,000 years ago suggest it might, Europe, including the UK, would rapidly become cooler.
Temperatures could drop by up to 10 degrees and the coast of Scotland would be frozen in sea ice.
The AMOC is a ‘system of systems’, Ezat explained, but the prospect of it weakening and collapsing is alarming.
Ezat said: “One clear reason for being worried is that we learned from looking at past climate change, including my recent study, that the AMOC could change dramatically on human-relevant time scales. And we know that a collapse or weakening of this system could result in major cooling in Northern Europe.
“Also, it has serious global implications including possible disruptions of the seasonal monsoons. Changes in AMOC could also impact marine ecosystems and resources, including fishery.
“We know that severe weakening of the AMOC isn’t unlikely, and if it happens it will have serious implications to the high latitude regions and beyond.”
Much of the warming caused by man-made climate change is absorbed by the oceans, and over time, this could cause changes to currents such as the AMOC.
Some measurements suggest that the AMOC is already weakening, with some research suggesting it might hit a ‘tipping point’ where it rapidly changes.
