Global surface temperature trends and the effect of World War II

TL;DR

This study identifies a statistically significant temperature increase coinciding with World War II across multiple datasets, suggesting human activity during that period impacted global surface temperatures, with implications for understanding current climate trends.

Contribution

The paper introduces a parametric analysis revealing a WW2-related temperature bump in global temperature records, linking it to human activity and providing insights into background temperature behavior.

Findings

A temperature bump during WW2 with amplitude 0.339°C

Temperature returned to baseline quickly after WW2

Current temperature increase rate is much higher due to quadratic effects

Abstract

Using parametric analysis (curve fitting) we find a persistent temperature bump, coincident with World War II (WW2), in eight independent time series, four land- and four ocean-based. We fit the data with a Gaussian on a quadratic background. Six parameters (constant, linear and quadratic background terms and the amplitude, position and width of the Gaussian) are free to vary. The mean fitted Gaussian amplitude is 0.339$\pm$ 0.065$\,^\circ$C, non-zero by 5.2$\sigma$ and therefore not accidental. The area is 2.0$\pm$0.5$\,^\circ$C yr. Temperature recovered to baseline rather quickly. Rather than coincidence, or systematic measuring error synchronized with WW2, we conjecture the bump is due to human activity, including the greatly increased combustion (relative to that era) of fossil and other fuels. Background surface temperature behavior, a byproduct of our study but largely independent of the WW2 bump, is far more consequential nowadays. The linear term, 0.747$\pm$0.023$\,^\circ$C/century, agrees well with other findings, but the present-day rate of increase, $\approx$2.5$\,^\circ$C/century, is far greater because of the quadratic term.