Variability of extremes in the 21st century as deduced from AIRS data

The reduced growth rate of surface temperatures in the first decade and a half of the 21-st century has sometimes been misidentified as a hiatus in the global warming. Unfortunately, the radiative heating of the surface resulting from the steady 2 ppm-per-year increase of CO2 in the atmosphere has never stopped. The myth of the global warming hiatus has been fomented by various reasons, and one of them is the lack of attention to fundamentals of physics. A simple effect of the first law of thermodynamics is that the rate of change of temperature can be negligible but the rate of heating of the system still be large, if the heat capacity of the system is large. Unsurprisingly, by observing warming in ever deeper layers, we now have evidences that the "lost" heating has been actually accumulating in the oceans. The atmosphere, by contrast, have much smaller heat capacity and have to discharge excess heating on shorter temporal scales to maintain thermal equilibrium.

The data from the Atmospheric Infrared Sounder (AIRS) on Aqua satellite is well suited to explore the resulting extremes. AIRS data is available since 2002, and provides daily extrema of all major thermodynamic variables. We explore the variability of extremes of surface air temperatures and geopotential heights at 500 mb by decomposing them in principle components (PC). We show that extremes, similarly to mean values, are contributed by El Nino Southern Oscillation (ENSO). Even after removing the strongest ENSO-affected components, impacts on ENSO are still observed implying complex nonlinear feedbacks. Reconstruction from most significant PC only allows us to demonstrate robust global patterns of variability of extremes. Owing to AIRS data, we are able to explore the patterns separately for day and night conditions, and land and oceans.