‘Pink noise’ and cli­mate change

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A NEW study from Yale Univer­sity says that pink noise may be the key to sep­a­rat­ing nat­u­ral cli­mate vari­abil­ity from cli­mate change that is in­flu­enced by hu­man ac­tiv­ity.

Pink noise or 1/f noise is a ran­dom noise in which ev­ery oc­tave (halv­ing or dou­bling of fre­quency) con­tains the same amount of en­ergy as against the more fa­mil­iar white noise, which has equal in­ten­sity across fre­quen­cies. Since it is also in­versely pro­por­tional to the sig­nal fre­quency, pink noise has more low fre­quency com­po­nents, and it is called pink be­cause vis­i­ble light with such an en­ergy spec­trum will have this colour. Elec­tronic cur­rents, earth­quakes, star lu­mi­nosi­ties and brain sig­nals are known to ex­hibit a type of noise. The Yale re­searchers John Wet­t­laufer and Sahil Agar­wal and Woosok Moon of Stock­holm Univer­sity found pink noise in the evo­lu­tion of tem­per­a­ture and other cli­mate vari­ables on decadal time scales both be­fore and af­ter the In­dus­trial Revo­lu­tion.


The re­searchers showed that such noise is due to nat­u­ral pro­cesses un­re­lated to emis­sions pro­duced by humans. The find­ing may

of the short­est timescale (in years) at which pink noise be­hav­iour ap­pears.

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