Oceans key to global cli­mate

Down to Earth - - SCIENCE -

MOST OF the de­bate on cli­mate change fo­cuses on green­house gases re­leased into the at­mos­phere. But it has emerged that ocean cir­cu­la­tion has an equally im­por­tant role. It was be­lieved that the se­vere cool­ing the earth un­der­went 2.7 mil­lion years ago was caused by changes in car­bon diox­ide (CO ) lev­els.

2 But analy­ses of ocean sed­i­ments (2.5 mil­lionto 3.3 mil­lion-year-old) sug­gest the cool­ing hap­pened due to the emer­gence of sub­sur­face ocean cur­rents. Th­ese cur­rents ab­sorb heat and CO from winds blow­ing close to the

2 ocean sur­face in the At­lantic and re­lease them in the Pa­cific. Sci­ence, Oc­to­ber 23 (on­line)

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