If am assuming Mr. Rahmstorf is qualified enough to understand the data. And with this part "So far, the study finds, we’re looking at a circulation that’s about 15 to 20 percent weaker. That may not sound like much, but the paper suggests a weakening this strong has not happened at any time since the year 900. Moreover, this is already more weakening than scientifically expected — and could be the beginning of a further slowdown that could have great consequences" I believe there is certainly a need to worry about.