Estimate of Critical Thresholds with Variance and Parabolic Approximations

It is wide scientific consensus that tipping points, in the form of rapid, large and irreversible changes in features of the climate system, are a possible scenario consequent to anthropogenic climate change. In literature there are several ways to detect the so-called Early-Warning-Signals, indicators (as increasing variance) that these changes are close to our current state and that the climate state is about to shift. We propose two novel indicators based on variance and parabolic approximations that expand the current theory to detect these EWSs. We show that the methods can produce estimations for the critical thresholds for particular systems. We finally show that our indicators predict close thresholds for the loss of ice of the Greenland ice sheet.