Attribution

Analyses of a newly constructed record of column ozone together with an existing record suggest that two thirds of the ozone recovery due to the reduction of ozone depleting substances over the past 25 years is compensated by a dynamically-caused ozone loss.

Record-breaking rates of increasing atmospheric methane concentrations in 2020 and 2021 are alarming, but puzzling, in view of declining methane emissions from fossil fuel in 2020. The authors show that interannual variation of both positive and negative feedbacks contribute positively to the rising methane concentration.

A multi-year marine heat wave in the northeast Pacific warming pool, as the one that occurred from 2019 to 2021, would almost certainly not have occurred in the absence of anthropogenic global warming, according to a climate model-based attribution study.

Companies commonly use renewable energy certificates to report progress towards emission reduction targets. However, this use of certificates is unlikely to result in actual emission reductions, which undermines the credibility of corporate emission reduction claims and their alignment with the Paris Agreement goal.

Regional climate warming amplified the exceptional heatwave on the Antarctic Peninsula observed in February 2020, suggest analyses of atmospheric flow analogs.

Atmospheric aerosols alter Earth’s radiation balance and serve as cloud condensation nuclei, but their climate forcing potential is poorly understood. This Review describes the occurrence of aerosols in the atmosphere, assesses the known impact on climate and proposes approaches to further constrain their climate effects.