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.

A new report has set out how the UK might respond to major disruptions to food supplies triggered by events such as war, extreme weather or cyber-attacks – and what can be done now to prevent such disruptions from escalating into a crisis.

Involving 39 experts from institutions including Anglia Ruskin University (ARU) and the University of York, the study maps how shocks to the food system, such as sudden price hikes or food shortages, could intensify pressure on already vulnerable parts of the system, ultimately increasing strain, instability and the risk of social unrest.

Chemicals brought in to help protect our ozone layer have had the unintended consequences of spreading vast quantities of a potentially toxic ‘forever chemical’ around the globe, a new study shows.

New research led by the University of East Anglia (UEA) shows how many tropical cities are predicted to warm faster than expected under 2°C of global warming.

Cities are often warmer than rural areas due to a phenomenon known as the urban heat island, which can be influenced by various factors, such as regional climate and vegetation cover. This can lead to increased heat-related health risks for some urban populations.

Published in Proceedings of the National Academy of Sciences (PNAS), the study combined state-of-the-art climate change projections with machine learning models to show how these urban heat islands can be amplified in many tropical and subtropical cities under climate change - mostly in monsoon regions such as India, China and Western Africa.