can easily gauge by te of a puddle on asummer’s day. Even someterranean  in a t  continually replenis occurred a little under six millionyears ago and provoked o science as ty Crisis.  continental movement closed trait of Gibraltar. As terraneandried, its evaporated contents fell as freser rain into oting tiness—indeed, making t dilute enougo freeze over larger areas than normal.

    t and puso an iceage. So at least theory goes.

    is certainly true, as far as ell, is t a little c, as le furted us.

    Oceans are t’s surface beeorologistsincreasingly treat oceans and atmospem, tle of our attention er is marvelous at ransporting . Every day,tream carries an amount of  to Europe equivalent to tput of coalfor ten years, h Canadaand Russia.

    But er also est days. For t reason tends to be a lag in tronomical start of aseason and tual feeling t t season arted. So spring may officially start in t it doesn’t feel like it in most places until April at t.

    t one uniform mass of er. temperature, salinity,depty, and so on s on  around, s climate. tlantic, for instance, is saltier too. tier er is t is, and dense er sinks. it its extra burden of salt, tlantic currents o tic,  deprivingEurope of all t kindly  of  transfer on Eart is knoion, s far belo detected by tist-adventurer Count von Rumford in 1797.

    2  surface ers, as t to ty of Europe, groo greatdeptrip back to tarctica,t up in tarctic Circumpolar Current,  can take 1,500 years for er to travel from term