Reviews & Analysis

The deepest reaches of the ocean are ventilated by sinking of cold and relatively saline seawater around Antarctica. Observations from the Australian sector of the Southern Ocean reveal a decline in sinking and abyssal ventilation, linked to dropping ocean salinity on the Antarctic shelf.

The ozone layer is slowly recovering due to the Montreal Protocol. The only exception is the ozone in the tropical lower stratosphere, which keeps decreasing. Now, a modelling study demonstrates that the tropical ozone loss is partly driven by ozone-depleting very short-lived substances that are not regulated by the Montreal Protocol.

At COP26 in Glasgow, major emitters significantly ratcheted up their climate commitments. Such increased ambition will substantially contribute to getting closer to the long-term goal of the Paris Agreement but more ambition is required, and mitigation might face different challenges in different regions.

Climate change mitigation politics is not delivering on climate targets. Recent research suggests that a general formal framework that represents the behaviour of citizens, consumers, firms and parties explains why.

The speed at which terrestrial organisms are shifting their ranges in response to climate is consistently lower than that predicted by models. However, the use of microclimate-based, rather than macroclimate-based, predictions virtually eliminates these discrepancies.

The rate of sea-level rise varies around the world, as do local infrastructure and standards for defending against the risks of flooding. Now research indicates that coastal communities can also have very different times left to act before defences fall short of those standards.

An immediate and rapid reduction in global emissions is required for many reasons. Integrated research supports the economic case for strong near-term climate action, even before accounting for expected negative impacts on biodiversity, health and tipping points.

Strong positive wetland methane climate feedbacks from global warming may occur but have not been accounted for in Earth system models. Now, model simulations show a substantial increase in methane emissions due to the stronger impact of warming over tropical wetlands.

Acclimation to climate change induces a reduction in the overall energetic cost for ectotherms, but most studies focus on a single species. Now, research shows that species competition can erode the energetic benefits of acclimation by affecting individual behaviour and energetics.

Modelled low-carbon pathways rarely incorporate processes reflecting social and political realities. Now two studies rise to this challenge by exploring the implications of a landmark initiative to phase out coal, showing that we need greater political ambition for faster transitions to keep a 1.5 °C outcome in sight.

Hybrid populations have long been perceived as a threat to distinct lineages and undervalued from a conservation perspective. Now, research suggests that hybrid populations may harbour gene combinations that improve their ability to cope with changing climate conditions.

Temperature affects both erosion and carbon cycling in the soil. Research now shows that under warming, the replacement of soil organic carbon lost by erosion increases but the preservation of deposited carbon decreases, with an overall rise in the cropland carbon sink.

Floating ice shelves that fringe Antarctica are at risk from warming ocean water and from above by warming air. Work now reveals that snow accumulation on ice shelves can minimize surface melt and ponding, but that future atmospheric warming will likely overpower this protection that snow provides, leaving ice shelves vulnerable to collapse.

A changing climate is altering vegetation phenology and probably impacts drought frequency and severity. Changes in vegetation phenology have some unexpected consequences on the trajectories of drought recovery.

Partisan politics is characterized by pejorative generalizations across opposition groups, but, similar to the groups being derogated, not all partisans are the same. Understanding the nature of partisan opposition to climate policy may help promote bipartisan projects to mitigate climate change.

Tipping elements are regions that are vulnerable to climate change and capable of sudden drastic changes. Now research establishes long-distance linkages between tipping elements, with the network analysis offering insights into their interactions on a global scale.