During your
last read you have found out that Ocean Circulation may answer your question of
how rapid climate changes can occur.In the next few sessions an important and famous scientist will help us understand how Ocean
Circulation and Climate are interconnected.
Nothing in
nature is static. Everything moves, forms and reforms constantly throughout the
geological timescale. Constant movement is also found in the world’s oceans.
Due to wind, rain and evaporation (e.g. Richter & Xie, 2010; Clark et al., 2002) water is being moved in, out and within each
large mass of water. In certain location this movement becomes directed and
forms large ocean currents flowing past landmasses and through continent
openings. This whole system consisting of many directed flows of current is referred
to as ocean circulation.
In 1982, a scientist by the name of W.S.
Broecker published his first idea of what the global ocean circulation may be
like. He thought of ocean circulation as a conveyor belt transporting water
along a route through all world oceans and back to its original position. This
means that oceans throughout the earth are interconnected. Thus, changing the
climate in one place will automatically influence the whole Earth.
The Great Ocean Conveyor Belt, taken from W.S. Broecker's "The biggest chill" (1982)
However, as
young critical scientists you have to ask Mr. Broecker one particular question to verify his hypothesis: what are the important factors that drive and influence the ocean conveyor belt?
If you have an idea, post your answer below.
Well - I have an idea. Feedbacks!!! Wooo!!! I think the phasing relationships between the hemispheres and the spatial extent of the climatic changes point to ocean-atmosphere feedback mechanisms. The Holocene illustrates this pretty well. It has been shown that Holocene abrupt changes show an anti-phase behaviour in parts of the Southern Ocean (Antarctica) to the D-O events in Greenland (Alley et al, 2005). The Byrd and GISP 2 cores support the idea of interhemispheric coupling through atmosphere and ocean teleconnections. I find Broecker's work interesting, especially his claim of the link between SST increase in the South Atlantic and deep water formation in the Southern Ocean (Broecker, 1998).
ReplyDeleteOther feedbacks e.g. sea-ice and freshwater forcing are important too! Well, I think Broecker touched on this in his 2006 paper. He suggested that the extent of sea-ice is a major control of the conveyor circulation, in particular the THC (Broecker, 2006). The bi-polar see-saw mechanism proposed by Knutti et al (2004) is also soo awesome!
Also, will you be covering the possibility of thresholds in the thermohaline circulation and hysteresis of the Atlantic meridional overturning circulation??? Thresholds are a thought-provoking area of research!
I am looking forward to reading your future posts!! :)
See you soon!
That is not bad. However, are feedbacks really what DRIVES ocean circulation?
ReplyDeleteI would have said that ocean circulation can be part of the whole feedback mechanism. But it is not driven by it.
Have a look at the latest posts and tell me what you think... ;)