A University of Washington study shows that existing models underestimate methane loss in the stratosphere and generate uncertainty in the global methane budget — a key metric for tracking climate change.

Kyoto, Japan -- Researchers at Kyoto University have proposed a new physical model that explores how disturbances in the ionosphere may exert electrostatic forces within the Earth’s crust and potentially contribute to the initiation of large earthquakes under specific conditions.

The study does not aim to predict earthquakes but rather presents a theoretical mechanism describing how ionospheric charge variations -- caused by intense solar activity such as solar flares -- could interact with pre-existing fragile structures in the Earth’s crust and influence fracture processes.

In the proposed model, fractured zones within the Earth’s crust are assumed to contain high-temperature, high-pressure water, potentially in a supercritical state. These zones behave electrically like capacitors and are capacitively coupled with both the ground surface and the lower ionosphere, forming a large-scale electrostatic system.

A temporary weakening of the atmosphere’s chemical capacity to break down methane, combined with elevated emissions from tropical wetlands, drove the sharp increase in atmospheric methane observed in 2020 to 2021, according to a new study. Methane (CH₄) is a significant contributor to atmospheric warming. In the early 2020s, the amount of atmospheric CH₄ grew faster than ever before observed, peaking at 16.2 parts per billion per year (ppb yr^-1), before declining to 8.6 ppb yr^-1 in 2023. It’s hypothesized that this surge was driven by a combination of increased natural emissions and a coincident decrease in the atmosphere’s oxidizing capacity, namely, fewer OH radicals available to chemically break down CH₄ in the atmosphere. However, the main drivers behind this event remain poorly understood, largely due to the difficulty in separating the impacts of changes in CH₄ emissions from changes in oxidizing capacity from OH radicals, particularly during the COVID period when OH precursor emissions were globally reduced. To resolve these uncertainties, Philippe Ciais and colleagues combined atmospheric models and a large suite of bottom-up inventories for various CH₄ sources to update the global and regional CH₄ budget for the period 2019 to 2023. Ciais et al. found that the rapid surge and subsequent decline in CH₄ growth between 2019 and 2023 were primarily driven by changes in the atmosphere’s ability to destroy CH₄, rather than by methane emissions alone. According to the findings, a global drop in OH radicals in 2020 to 2021 – followed by their recovery in 2022 to 2023 – explains about 80% of the year-to-year variation in CH₄ growth rate. The remaining share was largely due to increased CH₄ emissions from wetlands and inland waters, particularly in tropical wetlands in Africa, Asia, and the Arctic. In an accompanying Perspective, Euan Nisbet and Martin Manning discuss the study’s findings in greater detail.