Sink or Swim?

At the end of last week an interesting little article appeared on a number of news websites about a new report that had finally 'worked out' how much sea level had risen in the last two decades. At first this seemed like a bit of a non-story, there have been plenty of studies trying to quantify sea level rise before. However on a bit of further reading things get interesting because this is the first paper to be published combining data from ALL of the previous attempts to work out how much extra water has flowed into the oceans in the last few decades.

In theory this means that we should finally have a reliable record of previous anthropogenic sea level rise.

The graph above shows the paper's main conclusions. Both the Greenland and Antarctic ice sheets have been modeled separately and then combined to look at the overall picture. As you can see there is a very pronounced rise from the mid-nineties onwards following from a period of relative stability.

Of course the eagle eyed reader will noticed that this 'pronounced rise' is only about 11mm. Not only that but it can be argued that ice sheets and glaciers have been undergoing melting driven by human activity since before the start of the studies time period, so why does the data appear to only show a response from sea level in the late 1990s?

Still the finding have generated quite a bit of media interest (see the video below) and even if the results aren't exactly shocking they do demonstrate two things. Firstly the paper offers conclusive proof that sea level has been rising. Secondly the research itself shows that the scientific community can work together to produce reliable, informative pieces of literature. One of the main flaws in modern climate science has been its inability to work together  without producing confused and conservative conclusions. This then is a step in the right direction.

Don't take it all from me though, you can see a short video here of one of the academics behind the research and also read the paper itself.


Reference:

A Reconciled Estimate of Ice-Sheet Mass Balance. Shepherd et al. Science, Vol 338 no. 6111 pp.1183-1189. 2012.