Oxy­gen link to cli­mate change

New re­search sug­gests oxy­gen too plays a key role in cli­mate change

Down to Earth - - CONTENTS -

OXY­GEN IS not a green­house gas and that's why it has not been stud­ied in the con­text of cli­mate change. The pro­por­tion of at­mo­spheric oxy­gen has, how­ever, var­ied be­tween 10 per cent and 35 per cent over the past 541 mil­lion years.

Now, Christo­pher Poulsen and col­leagues at the Univer­sity of Michigan have de­vel­oped a model to show how these fluc­tu­a­tions im­pacted cli­mate. In pe­ri­ods when oxy­gen lev­els de­clined, the re­sult­ing drop in at­mo­spheric den­sity led to in­creased sur­face eva­po­ra­tion, which in turn led to pre­cip­i­ta­tion in­creases and warmer tem­per­a­tures. While not as crit­i­cal to cli­mate as heat­trap­ping car­bon diox­ide gas, oxy­gen plays a key role. Cur­rently, oxy­gen com­prises about 21 per cent of Earth's at­mos­phere by vol­ume. Science, June 11

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