means a number of to different people, it appears. In November 2002, Carl unscpublis in Science, quot; Is tion?,quot; in  to signify at least seven different pion at tion driven by differences in density or buoyancy, quot;meridional overturning circulation of mass,quot; and soon)-to do ions and transfer of , tiously vague and embracingsense in w here.

    Nortlantic to t t and er te is enormous.

    (As for tion of   takes a drop ofer to get from one ocean to anot scientists can measure compoundsin ter like c  in t of measurements from different deptions t ter’s movement.)tion not only moves  around, but also o stir up nutrients asts rise and fall, making greater volumes of table for fisures. Unfortunately, it appears tion may also be very sensitive toco computer simulations, even a modest dilution of tcontent—from increased melting of t, for instance—could disrupt trously.

    t favor for us. tremendous volumes of carbon andprovide a means for it to be safely locked aies of our solar system is tt 25 percent more brigem was young.

    ted in a muc AubreyManning  it, “tely catastropon t it appears t our world ed.”

    So able and cool?

    Life does. trillions upon trillions of tiny marine organisms t most of us ure atmosp falls as rain and use it (in combination o make tiny s frombeing reevaporated into tmosp iny foraminiferans and coccolito ttomof to limestone. It is remarkable, ural feature like te Cliffs of Dover in England, to reflect t it ismade up of