David Fields of the Monterey Bay Aquarium Research Institute has a paper in tomorrow’s Science (press release here) suggesting an interesting anthropogenic warming fingerprint: plankton in varves on the ocean floor. Both warm- and cold-water forams can be found, and the relative abundances of the various types works as a climate proxy.
Fields sees the “regime shift” of the mid-1970s (most famously called the Pacific Decadal Oscillation), and suggests that the patterns in the sediments from the late 20th century are unprecedented in the 1,400-year record. In other words, 20th century warming is fundamentally different than variations seen during that period, with “a deep, penetrative warming not observed in previous centuries.”
(Hat tip me.)
Uh-oh, does the graph of this bear any resemblance to a well-known sporting implement? The press release even makes an analogy to tree ring records. It’ll be interesting to see how much of a trace there is of the MWP and LIA, although the release seems to make it clear that the MWP is at least of less amplitude than the current warming. This new paper is just in time for the AR4, too. If I were one of them denialists I’d probably suspect some kind of conspiracy.
I’m really looking forward to seeing the details, but from the description the paper may shed light on whether the PDO is even a distinct climate cycle. Even if it is, it appears that the amplitude of that mid-’70s positive phase shift would have been greatly enhanced by AGW.
BTW, probably you saw this when it came out a few months ago, but foraminifers as climate proxies are very prominent lately: See http://www.sciencemag.org/cgi/content/abstract/310/5750/1009?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Lea&searchid=1136496270736_14806&FIRSTINDEX=0&journalcode=sci, a paper with some really large implications, and other articles by Lea and various co-authors. (I found the little tease about EPICA at the end of the full article a little amusing. Gee, do you suppose Lea knows something?). It’s hard for me know for sure with my limited journal subs, but Science in particular seems to be giving such papers a lot of play. One gets the impression that the AR4 is going to feature the hell out of this stuff.
I’d suggest all of this as a subject for an exciting in-depth article for you were it not for the small problem of the public finding such things boring as hell (pun intended).