Extinction risk under coloured environmental noise

Positively autocorrelated red environmental noise is characterized by a str ong dependence of expected sample variance on sample length. This dependenc e has to be taken into account when assessing extinction risk under red and white uncorrelated environmental noise. To facilitate a comparison between red and white noise, their expected variances can be scaled to be equal, b ut only at a chosen time scale. We show with a simple one-dimensional popul ation dynamics model that the different but equally reasonable choices of t he time scale yield qualitatively different results on the dependence of ex tinction risk on the colour of environmental noise: extinction risk might i ncrease as well as decrease when the temporal correlation of noise increase s.