Comparative Analysis of Arctic and Antarctic Warming Acceleration Using ERA5 Reanalysis and Earth’s Energy Imbalance

Abstract

Global warming has exhibited distinct impacts on the Arctic and Antarctic for decades. Because of the significant geographic differences between the Arctic and Antarctic, the warming rates are different. However, it remains uncertain whether their long-term warming trends are accelerating at comparable rates. This study investigates the differences in global warming acceleration between the Arctic and Antarctic using ERA5 monthly reanalysis temperature data from 2000 to 2026 and examines their relationship with Earth's Energy Imbalance (EEI), a measure of whether the Earth is gaining more energy than it is losing. To ensure a consistent comparison of the two polar regions, monthly 2-meter air temperature data were averaged into annual mean temperatures, and linear regression was applied to quantify long-term warming trends. Changes in Earth's Energy Imbalance were evaluated using the NASA CERES EBAF Top-of-Atmosphere net radiation product from 2000 to 2026, while Arctic September sea ice extent was analyzed using the NSIDC Sea Ice Index Version 4 dataset from 2000 to 2025, because of the unavailability of the 2026 September sea-ice extent data.

The results show that the Arctic warmed at approximately 0.085 °C/year, almost twice the Antarctic warming rate of approximately 0.040 °C/year. Over the same period, Earth's Energy Imbalance increased by approximately 0.057 W/m²/year, which indicates a continued increase in the amount of energy maintained by the climate system. To contrast, Arctic September sea ice extent declined at an average rate of approximately 0.069 million km²/year, demonstrating a substantial long-term loss of sea ice. These findings suggest that increasing Earth's Energy Imbalance is closely associated with accelerated Arctic warming and continued sea ice decline, while Antarctic warming remains comparatively slower. This study improves our understanding of how the Arctic and Antarctic respond differently to climate change and provides insight into the factors that drive global warming acceleration in the polar regions.