Quantifying the Thermodynamic Drivers of Recent Acceleration in Earth’s Energy Imbalance: A Radiative Transfer and Top-of-Atmosphere Flux Analysis

Abstract

Earth’s Energy Imbalance (EEI) serves as the primary physical metric for tracking the accumulation of thermal energy within the climate system. Recent satellite observations indicate a rapid, non-linear acceleration in this imbalance, presenting a vital problem in non-equilibrium thermodynamics. This paper isolates and quantifies the physical drivers underlying this recent radiation flux anomaly. Utilizing top-of-atmosphere (TOA) net radiation data from NASA's Clouds and the Earth’s Radiant Energy System (CERES) satellite constellation, we construct a conceptual framework to differentiate between longwave heat trapping from greenhouse gas accumulation and shortwave variations driven by cloud reflectivity feedbacks. Specifically, we investigate the aerosol indirect effect, evaluating how recent global reductions in industrial sulfur emissions from maritime shipping have modified cloud droplet formation, thinned cloud density, and lowered global reflectivity. By applying radiative transfer models and spectral fingerprinting, we map the observed flux anomalies against the thermal response of the troposphere-ocean boundary layer. Our modeling suggests that while greenhouse gases remain the foundational long-term driver of warming, a significant portion of the post-2020 acceleration is caused by a sudden reduction in sunlight reflection. This process effectively unmasks the latent heat trapping capacity of the atmosphere. These findings provide a rigorous, physics-based constraint on climate sensitivity metrics, offering a precise accounting of the planet's changing thermal equilibrium.