‘Pink noise’ and climate change
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.