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An Earth system model estimates that natural halogens, of marine biotic and abiotic origin, remove about 13% of present-day global tropospheric O₃. Projections suggest this ratio is stable through 2100, with high spatial heterogeneity, despite increasing natural halogens.

Short-lived halogens have a substantial indirect cooling effect on climate and this cooling effect has increased since pre-industrial times owing to anthropogenic amplification of natural halogen emissions.

A Review of the impacts of short-lived halogens on air quality and climate identifies gaps in our knowledge of short-lived halogen emissions, chemistry, and the environmental and climate impacts.

In contrast to the overall recovery of stratospheric ozone, ozone depletion in the tropical lower stratosphere has been ongoing over recent years. Here the authors show that currently unregulated halogenated ozone-depleting very short-lived substances play a key role in this ongoing depletion.

Reduction of gaseous Hg(II) compounds drives atmospheric mercury wet and dry deposition to Earth surface ecosystems. Global Hg models assume this reduction takes place in clouds. Here the authors report a new gas-phase Hg photochemical mechanism that changes atmospheric mercury lifetime and its deposition to the surface.

Pattern-based detection and attribution methods that make use of trend pattern information as a function of month and height provide evidence that reduction of ozone-depleting substances has resulted in the beginning of Antarctic ozone recovery.

Methane is a powerful greenhouse gas and previous studies focus on its sources with less attention on the loss. Here the authors show that reactive halogen species, not considered in climate projections, significantly reduces the methane loss, increasing its lifetime, burden, and radiative forcing.

Methane, a powerful greenhouse gas, has comparable anthropogenic and natural sources, complicating emission control. Increasing reactive chlorine has been proposed for mitigation. This study assesses the global environmental impacts of such proposal.

The Antarctic ozone hole has had far-reaching impacts, but effects on geochemical cycles in polar regions is still unknown. Iodine records from the interior of Antarctica provide evidence for human alteration of the natural geochemical cycle of this essential element.

Climate change can exert a significant effect on the ozone recovery. Here, the authors show that the Arctic polar vortex shift associated with Arctic sea-ice loss could slow down ozone recovery over the Eurasian continent.

High ozone and low water structures in the tropical western Pacific are commonly attributed to transport from the stratosphere or mid-latitudes. Here, Anderson et al. show these structures actually result from ozone production in biomass burning plumes and large-scale descent of air within the tropics.

Despite its chemical importance, the evolution of atmospheric iodine concentrations over time is unknown. Here, the authors show that North Atlantic atmospheric iodine levels have tripled since 1950, and propose ozone pollution and enhanced biological production Arctic sea ice thinning as a primary driver.

The strength of the global meridional overturning circulation in the stratosphere is uncertain. An analysis of satellite data, reanalyses and model simulations reveals a strength of 6.3–7.6 × 10⁹ kg s⁻¹, but no convergence at higher altitudes.

Large amounts of water vapour released to the stratosphere during the 2022 Hunga-Tonga hydromagmatic volcanic eruption led to decreased sulfur dioxide aerosol lifetime, increased sulfate particle size and a doubling of stratospheric aerosol optical depth, according to numerical simulations.