A group of colleagues have succeeded in producing the first continuous proxy record of sea level for the past 2000 years. According to this reconstruction, 20th-Century sea-level rise on the U.S. Atlantic coast is faster than at any time in the past two millennia.
Good data on past sea levels is hard to come by. Reconstructing the huge rise at the end of the last glacial (120 meters) is not too bad, because a few meters uncertainty in sea level or a few centuries in dating don’t matter all that much. But to trace the subtle variations of the last millennia requires more precise methods.
The international Aquarius/SAC-D satellite was successfully launched yesterday (thankfully!). Media coverage was good – except for the almost absolute avoidance of the term ‘salinity’ to describe the concentration of salts in the surface ocean that Aquarius will retrieve – oh well. But what is Aquarius going to see, and why is it important?
Two and a half years ago, a paper was published in Nature purporting to be a real prediction of how global temperatures would develop, based on a method for initialising the ocean state using temperature observations (Keenlyside et al, 2008) (K08). In the subsequent period, this paper has been highly cited, very often in a misleading way by contrarians (for instance, Lindzen misrepresents it on a regular basis). But what of the paper’s actual claims, how are they holding up?
Yesterday, the New York Times ran an excellent cover story on sea level rise, together with two full pages inside the paper, fancy graphs and great photographs (online version here). The author, Justin Gillis, researched the piece for months, visited Greenland and talked to most of the leading scientists in the field – many of which he cites in the article. The science presented is correct and up-to-date and the story is a gripping read. That’s how science journalism should be!
What is going on in Greenland? (c) The New York Times.
Guest Commentary by Chris Colose
One of the most intriguing and well-studied climatic events in the past is the Younger Dryas (YD), a rather abrupt climate change between ~12.9 and 11.6 thousand years ago. As the world was slowly warming and ice was retreating from the last glaciation, the YD effectively halted the transition to today’s relatively warm, interglacial conditions in many parts of the world. This event is associated with cold and dry conditions increasing with latitude in the North, temperature and precipitation influences on tropical and boreal wetlands, Siberian-like winters in much of the North Atlantic, weakening of monsoon intensity, and southward displacement of tropical rainfall patterns. RealClimate has previously discussed the YD (here and here) however there have been a number of developments in recent years which deserve further attention, particularly with respect to the spatial characteristics and causes of the YD.
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