Abrupt cooling in Europe
A new reconstruction of past climate change shows that a warm climate in northern Europe can be hit by a sudden cooling associated with an interruption of the North Atlantic Ocean circulation. An international team of researcher, including IBED researcher Dr Stephan Engels, investigated the development of northern European climate about 120 thousand years ago and recently published their findings in in Quaternary Science Reviews.
Warmth before an ice age
The warm period preceding the last ice age is called the Eemian and was characterized by warmer-than-present temperatures in large parts of the globe. The Eemian climate evolution can therefore serve as an analogue for a future warmer climate. The study of fossil remains from plants and insects preserved in geological deposits in Northern Finland revealed an abrupt climatic cooling event that happened in an otherwise warm climate. During this event the temperatures dropped 2-4 °C and remained low for a period of 500–1000 years. Comparison with seafloor sediment records from the Norwegian Sea and the North Atlantic indicates that the rapid cooling was associated with a sudden slowdown in North Atlantic deep water formation and a reduction in the northward extension of the Gulf Stream that transports heat to northern Europe.
The new evidence shows that the last time when temperatures were significantly warmer than today, climate instability occurred.
‘This may have been caused by meltwater coming from the Greenland Ice Sheet, disrupting the North Atlantic Ocean circulation. While the exact mechanism behind the sudden cooling still remains uncertain, the study illustrates the potential for major climatic instability in and around the North Atlantic region under future global warming’, says Karin Helmens at the Department of Physical Geography, Stockholm University.
The study was performed by an international research group led by Dr Karin Helmens from Stockholm University and Bolin Centre for Climate Research (Sweden). The group also includes scientists from the University of Helsinki (Finland), University of Bergen and Bjerknes Centre for Climate Research (Norway), and VU University Amsterdam and University of Amsterdam (The Netherlands).
Karin F. Helmens, J. Sakari Salonen, Anna Plikk, Stefan Engels, Minna Väliranta, Malin Kylander, Jo Brendryen, Hans Renssen (2015). Major Cooling Intersecting Peak Eemian Interglacial Warmth in Northern Europe. Quaternary Science Reviews. In press.