Brochure from the Deutsches Klima-Konsortium and the German Marine Research Consortium
There has been lots of speculation about the Gulf Stream. But what kind of scientific evidence exists? Nine experts summarize this evidence in this brochure. One of the key messages: The Gulf Stream circulation will not collapse in the near future. But this is not a reason to be complacent.
The Gulf Stream circulation acts like an air conditioner for Europe: it flattens out temperature peaks and troughs. The system of currents provides an elementary contribution to the moderate climate of northern Europe because it transports warm water from the subtropics to the Arctic. This important role in our society has been treated in books and films, such as Roland Emmerich’s ice age scenario “The Day After Tomorrow”. Scientists do not fear such extreme cooling; a sudden failure of the Gulf Stream circulation is extremely unlikely according to current research. However, researchers expect a slowdown in the future. This sounds less spectacular, but it would have a significant impact: the rise in sea level could be increased in some regions, precipitation patterns would shift, and ecosystems and fish populations in the Atlantic would be affected.
The publication of the Deutsche Klima-Konsortium (DKK) and the Konsortiums Deutsche Meeresforschung (KDM; German Marine Research Consortium) explains the research behind these results and takes a look at the past, present, and future of the Gulf Stream circulation. It is available in English and German.
There can be no scientific information about a long-term weakening trend since 1900 because not enough observational data is available. In the past 20 years, researchers have been able to analyze the ocean more accurately thanks to state-of-the-art methods and technologies. However, this period is not sufficient to derive climatic trends. Instead, the researchers have found that the Gulf Stream circulation has been pretty stable over the past 20 years and showed a lot of natural fluctuations. This natural variability makes it even more difficult to prove any possible human influence on the Gulf Stream circulation.
This is no reason for complacency. The scientific consensus, derived from modeling, is that a significant weakening of the Gulf Stream circulation is expected by the end of this century. It is difficult to predict exactly how strong this weakening will be. Whether and how much the Gulf Stream circulation will change depends primarily on how the anthropogenic emissions of greenhouse gases will develop. If researchers use the worst-case scenario of the Intergovernmental Panel on Climate Change (IPCC) in their climate models, the Gulf Stream circulation decreases by an average of about 30% in all the models. This scenario assumes unchecked greenhouse gas emissions. But factors such as the melting of the ice in Greenland due to climate change have not yet been considered. Therefore, one of the key research questions is the influence of the Greenland meltwater on the Gulf Stream circulation. It could slow the overturning circulation if it reaches the regions where deep-water formation occurs – regions that are basically the drivers of the circulation.
The scientists work together in an interdisciplinary strategy group of the DKK and KDM that studies ocean and the climate. They perform their research at the member institutions of the two scientific associations: