Scientists suggest that these are the circumstances we may be approaching. During the Last Interglacial Period, global warming caused so much Arctic ice to melt that Atlantic currents collapsed.
According to a new study, crucial Atlantic Ocean currents collapsed shortly before the last ice age due to global warming.
The Nordic Seas—the Greenland, Iceland, and Norwegian seas—saw a severe cooling as a result of the weakened currents, while the surrounding oceans warmed. As the planet warms due to climate change and temperatures approach those of the pre-last ice age, scientists warn that we may be on the verge of experiencing the same thing once more.
Mohamed Ezat, an associate professor and paleoceanographer at The Arctic University of Norway, said in an email to Live Science, “Our study is indeed alarming regarding what we might be heading to.”
Between the two preceding ice ages, the Last Interglacial period (130,000 to 115,000 years ago) was a comparatively warm time in Earth’s history marked by smaller ice sheets, greater temperatures, and rising sea levels. With temperatures rising 1.8 to 3.6 degrees Fahrenheit (1 to 2 degrees Celsius) above preindustrial levels, climate scientists say the Last Interglacial offers a warning for the near future if nations don’t cut greenhouse gas emissions.
“The time period we investigated, the Last Interglacial, is an interesting and very timely period to study,” Ezat stated. “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.”
The Gulf Stream and the larger Atlantic Ocean current system known as the Atlantic Meridional Overturning Circulation (AMOC) depend heavily on Nordic Sea currents. With warm waters from the Southern Hemisphere riding northward on the ocean surface before cooling and sinking to the bottom in the North Atlantic to return south, the AMOC acts as a massive conveyor belt and is crucial for warming the Northern Hemisphere.
Because fresh water flowing into the North Atlantic dilutes surface waters and keeps them from sinking to the bottom to generate deep currents, melting ice in the Arctic can have a substantial effect on the AMOC. Global warming is causing the AMOC to slow down already, according to research, and scientists predict that the system may come to a complete stop in the ensuing decades.
The AMOC operates similarly to an enormous conveyor belt. NASA Goddard Space Flight Center Scientific Visualization Studio is the source of the image.
In an open letter to the Nordic Council of Ministers, an intergovernmental body that fosters collaboration among the Nordic nations, forty-four prominent climate scientists raised concerns about the AMOC earlier this month. Significant cooling in the Northern Hemisphere and disastrous changes in tropical monsoon patterns were among the dangers associated with an AMOC collapse, according to the letter.
There is significant uncertainty in estimating the timelines; however, climate models indicate that the AMOC may disappear before 2100. “Looking at the distant past of the Earth’s climate history in particular when it was warmer than today can reduce such uncertainties,” Ezat stated.
Ezat and his colleagues examined both fresh and pre-existing data from sediment cores from the Norwegian Sea for the new study. In order to reconstruct the distribution of sea ice, sea surface temperature, salinity, deep ocean convection, and meltwater sources during the Last Interglacial, they compared these data with comparable information found in North Atlantic strata.
The findings, which were released in the journal Nature Communications on October 27, indicate that during the Last Interglacial, deep-ocean current development in the Norwegian Sea was impeded by Arctic meltwater. This significantly slowed the AMOC’s southward movement, which in turn slowed the Northern Hemisphere’s heat-producing engine.
“In brief, we found cooling in the Nordic Seas that we were able to link to a warming global climate and enhanced melting of sea ice,” Ezat stated.
According to Ezat, the analysis shows what can happen to the AMOC soon. Scientists predict ice-free summers by 2050 as satellite observations reveal a sharp drop in Arctic sea ice during the previous 40 years. The AMOC will be significantly impacted by these.