Climate change: across time and frequencies

Abstract

We use continuous wavelet tools to characterize the dynamics of climate change across time and frequencies. This approach allows us to capture the changing patterns in the relationship between global mean temperature anomalies and climate forcings. Using historical data from 1850 to 2022, we find that greenhouse gases, and CO$_2$ in particular, play a significant role in driving the very low frequency trending behaviour in temperatures, even after controlling for the effects of natural forcings. At shorter frequencies, the effect of forcings on temperatures switches on and off, most likely because of complex feedback mechanisms in Earth's climate system.