Journal Article

A Simple Relationship Between the Magnitude and Spatial Extent of Global Surface Temperature Anomalies

Huybers, Peter, Fried, Caleb

2024

Overview

Preparing for climate change requires an understanding of the degree to which global warming has regional implications. Here we document a strong relationship between the magnitude and extent of warming and explain its origin using a simple model based on binomial statistics. Applied to HadCRUT5 instrumental observations, the model shows that 96% of interannual variability in the proportion of regions experiencing anomalous warmth over the last century can be explained on the basis of the magnitude of global mean surface temperature (GMST) anomalies. The model performs similarly well when applied to a variety of unforced and forced model simulations and represents a general thermodynamic link between global and local warming on annual timescales. Our model predicts that, independent of the baseline that is chosen, 95% of the globe is expected to experience above‐average annual temperatures at 0.7°C of GMST warming, and 99% at 1.0°C of warming. Plain Language Summary Whereas many studies focus on global mean surface temperature (GMST), it is also critical to understand the spatial patterns of this warming in preparing for a warmer world. Using a simple statistical model, we describe a strong relationship between GMST and the spatial extent of above‐average temperature anomalies each year. This relationship is shown to hold across various model simulations and historical temperature data, capturing both annual and decadal trends. We can use our model alongside projections to gain insight into the extent of warming variations. For instance, 1°C GMST warming from a given baseline climate generally corresponds to a world in which 99% of places across the globe will be anomalously warm every year. Key Points A simple statistical model relates the proportion of Earth's area that is anomalously warm to global mean surface temperature (GMST) The model predicts 96% of the interannual variance in the proportion of anomalous warmth between 1900 and 2021 on the basis of GMST 1.0°C of GMST warming corresponds to 99% of the globe being anomalously warm, independent of baseline

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Annual temperatures / Anomalies / Climate / Climate change / Global temperatures / Global warming / Historic temperatures / Interannual variability / Mathematical models / Mean / Statistical models / Surface temperature / Temperature / Temperature anomalies / Temperature data / Temperature requirements