New research published in Scientific Reports in February indicates that a warm ocean surface water prevailed during the last ice age, sandwiched between two major ice sheets just south of Greenland.
Extreme climate changes in the past Ice core records show that Greenland went through 25 extreme and abrupt climate changes during the last ice age some 20.000 to 70.000 years ago. In less than 50 years the air temperatures over Greenland could increase by 10 to 15 °C.
However the warm periods were short; within a few centuries the frigid temperatures of the ice age returned. That kind of climate change would have been catastrophic for us today. (link)
Ice core records from Antarctica also show climate changes in the same period, but they are more gradual, with less severe temperature swings.
The Nature Scientific Report study shows that an area of the Nordic Seas, just south of Iceland, followed the Antarctic pattern of warming and cooling. Which is strange since it is so close to Greenland.
"We had expected to see sudden climate changes. But sediment core records from the area show that the climate changes here were actually gradual, and quite identical to Antarctic climate changes." says CAGE professor Tine Rasmussen, the principal author of the paper.
Gulf Stream holds the answers
Then, as now, the circulation of Atlantic Ocean, with currents such as the Gulf Stream, regulated transportation of heat to this area. Simply put, the surface currents transport heat from the southern and tropical Atlantic toward the North Atlantic.
" The Nordic seas between Norway and Greenland play a crucial role for the current patterns of the Atlantic Ocean. They act as a pump. Here the warm and salty surface water cools down during winter. It becomes heavy and is pumped down to the bottom before returning to the Atlantic, where it continues as a deep current all the way to the Antarctic region. " co-author Erik Thomsen from Aarhus University ( link) points out.
Without this pump, the north-south current system would slow down considerably. Changes in this circulation can have a profound impact on the global climate system.
During the ice ages this circulation was assumed to work as a seesaw in the playground - going up and down in opposite directions with an axis somewhere around the equator. The idea is that when it warmed in the north, it cooled in the south and vice versa. But Rasmussen and colleagues indicate another scenario.
Rewriting the seesaw hypothesis
During the coldest periods of the last ice age the Nordic seas were covered with a permanent layer of sea ice. The pump stopped transporting the heat northward. The heat accumulated in the southern oceans. However, the warming was not restricted to the south.
" Our results show that it continued all the way to Iceland. The warming was slow and gradual, and happened simultaneously in both hemispheres. Little by little the warm Atlantic water penetrated into the Nordic sea underneath the ice cover. It melted the ice from below. Once the ice was gone, the pump started up again, bringing additional warm water into the Nordic seas. And we got a warmer period for 50 years. " says Rasmussen.
Large ice sheets continued however, to cover the continents around the Nordic seas. In contact with the warm ocean water they started calving. This delivered icebergs and fresh water into the sea and caused a cooling down of the surface water. The seas were again frozen. And the pump slowed down.
The warm ocean blob of the ice ages rewrites the understanding of the ocean circulation systems, and how they affected the extreme climate changes of the past. The seesaw was actually more of a 'push and pull' system.
"There are no symmetrical processes in the north and the south - the climate changes were principally governed by simultaneous warming and the constant closing and re-opening of the sink pump in the Nordic seas" says Tine Rasmussen.
Maja Sojtaric | EurekAlert!
Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft
How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.
New Manufacturing Technologies for New Products
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
22.06.2017 | Life Sciences
22.06.2017 | Materials Sciences
22.06.2017 | Materials Sciences