Quantifying the ocean's effect on Europe's climate
Europe's moderate climate is strongly influenced by the North Atlantic thermohaline ocean circulation (THC) that transports heat from the tropics to the shores of Europe. In 2005, research suggested that the THC may be slowing down, which could have dramatic effects on climate, in particular in Northern Europe. Further investigation was needed. For four years, “Thermohaline Overturning: At Risk?” (THOR), a project under the FP7, explored the dynamics of this circulation. Coordinated by Prof. Detlef Quadfasel at the University of Hamburg, THOR comprised a consortium of 21 scientific groups from 9 European countries. Together, they studied the stability of this oceanic circulation and quantified its impact on the regional climate.
THOR's scientists employed innovative tools for ocean observations and a suite of models from leading European climate research institutions to define the present state of the Atlantic circulation, explore its natural changes or variability and predict its future development. Forecasting the state of the global ocean and atmosphere on a time scale of a decade was one of the main goals of THOR. The research showed that good ocean state estimates, such as those based on continuous measurements, are a prerequisite for skilful predictions, but the largest errors arise from model uncertainties.
Thankfully, the results of THOR showed that there was no need for panic as the earlier research had claimed since the ocean circulation was found to be more stable than expected.
“The conclusions made previously were based on only a few measurements and didn't show the entire picture. There simply weren't enough data points,” says Quadfasel.
“We are now certain that a failure of the THC will not happen within a few years and it probably won't happen in the next decades either,” explains Quadfasel.
With the innovative tools developed under THOR, scientists can now separate man-made changes from natural variability and better predict the influence and potential effects of increased greenhouse gas concentrations in the atmosphere, volcanism, and changes in solar intensity.
Despite the lack of “Apocalypse Now” from THOR's findings, experts agree that it is crucial to continue the surveillance through adequate observation and modelling systems in order to allow skilful climate predictions on seasonal to decadal time scales. Forecast services derived from such predictions to different economic sectors (agriculture, water management, health etc) are very beneficial to their planning and preparedness and will allow society to elaborate adaptation strategies to climate variability and change. THOR’s scientists will therefore continue their research in a follow-up project, NACLIM, which is also financed by the FP7 and was launched in November 2012.
With €9.2 million in funding under the FP7, THOR was a truly European project, bringing together expertise and intellectual resources from a number of different institutions. The progress achieved in understanding European climate variability was only possible through this Europe-wide and interdisciplinary cooperation.