Research Briefing in 2023

Aerial photographs collected during mapping expeditions of Greenland’s coastline represent the only robust, widespread observations of twentieth-century glacier change for this vast island. We use this unique dataset to document the response of Greenland’s peripheral glaciers to climate change over approximately 130 years, providing enhanced confidence that recent changes are exceptional on a century timescale.

Assessing progress and gaps in climate adaptation is a key policy concern, and also raises scientific challenges around which metrics should be used and who should assess progress. A structured expert judgement using local case studies shows that, for coastal areas, today’s global adaptation is halfway to achieving the full adaptation potential.

An insight into the global patterns of marine heatwaves from the surface to depths of 2,000 m reveals that subsurface events are more intense and long-lasting than surface ones. Biodiversity exposure to the effects of marine heatwaves is higher at depths of 50–250 m, suggesting that subsurface biodiversity could be at considerable risk.

A multi-model analysis shows that the incorporation of advances in damage functions — namely growth effects — substantially increases the social cost estimates of methane and nitrous oxide, although uncertainty remains.

Emission savings from three circular economy strategies aiming to close, slow and narrow China’s bulk material loops have been analysed using an integrated model. This analysis highlights that material recycling delivers substantial emission cuts, but demand reduction is equally crucial for decarbonizing bulk materials.

Weather station records are too short and sparse to effectively detect the signature of climate change in Antarctica. Using the isotopic composition of ice cores as a temperature proxy suggests that Antarctica is warming faster than the global average temperature and expectations from climate models for the region.

A network of more than 100 researchers tracked trees for up to 30 years in forest plots across South America, enabling estimation of the impacts of record temperatures and drought on carbon dynamics. The carbon sink in these forests ceased during the 2015–2016 El Niño, with drier forests losing the most carbon.

Arctic uplands consume atmospheric methane, but whereas methane emissions are reasonably well studied, Arctic soil methane uptake is poorly understood. High-resolution measurements show that the Arctic soil methane sink might currently be underestimated, and is driven by soil moisture and labile carbon availability, implying increased methane uptake with climate change.

Satellite-based analysis indicates that the relative change in cloud droplet number concentration with relative change in aerosol concentration is sublinear, contrary to common assumptions. The revised nonlinear method predicts that in heavily polluted regions the additional warming due to improvements in air quality will occur two to three decades later than predicted by the linear method.

The stability of the West Antarctic Ice Sheet is uncertain on a rapidly warming planet. Geoengineering through solar radiation modification could halt global warming and potentially delay the demise of the ice sheet. But in high-greenhouse-gas-emission scenarios, collapse of the ice sheet ensues despite such intervention.

A net-zero change in tree cover is often considered to have no impact on the biophysical effects of forests. Satellite observations now reveal an asymmetric influence of gross tree-cover gain versus loss on land surface temperature. Neglecting this influence might lead to biases in quantifying the biophysical effects of forests.

Nature-based solutions, such as urban green spaces, are shown to contribute to carbon emissions reduction and carbon sequestration, and also to have valuable indirect effects and behavioural impacts. Implementing such solutions could achieve carbon neutrality within the decade in several major cities in Europe.

We established a comprehensive assessment framework to explore the carbon dioxide (CO₂) emissions reduction potential from coal–biomass co-firing power plants with retrofitted carbon capture and storage (CBECCS) in China. Optimal spatiotemporal deployment of the CBECCS transition could achieve CO₂ mitigation of 1.6 Gt yr⁻¹ in 2040 and 41.2 Gt cumulatively over the period 2025–2060.

An integrated assessment model calibrated on past economic and climate development is used to estimate the historical time-series of the social costs of carbon from 1950 to 2018. The extent to which individual countries reduced global wealth through their fossil and industrial-process carbon dioxide emissions was then assessed.

The potential effect of globally expanding organic farming on cropland soil organic carbon stocks has been estimated using a modelling approach. The results reveal that large-scale expansion of organic farming could lead to a reduction in soil organic carbon stocks unless appropriate farming practices, such as increased cover cropping, are adopted.

Better adaptation methods are needed in the face of rapid climate change. A pilot process for inclusive adaptation planning reveals that empowering citizens to identify climate impacts, and to discuss interventions to adapt to them, leads to better awareness of and preparedness for future climate change events.

When the Arctic Ocean will become free of sea ice is uncertain in climate-model projections. If a mismatch between the observed and the modelled sensitivity of sea ice to changes in atmospheric circulation is properly accounted for, then projections show that ice loss is slower and the Arctic could be sea-ice-free a decade later.

The value of climate change mitigation largely depends on the social discount rate, which has almost exclusively been influenced by economists. A survey of expert philosophers shows that, as a group, they support the same social discount rate as economists, resulting in the same mitigation policy, but for different ethical and practical reasons.

Global runoff increases with carbon dioxide (CO₂) concentration because of the synergistic effects of physiological responses to CO₂ and the responses of vegetation and soil moisture to CO₂-induced climate change. These land surface changes are far more important than the direct effects of climate change on global runoff in a CO₂-warmed world.

Estimations of the risk from sea-level rise are often based on the amount of property inundated by water. However, risk measurements based on isolation — being cut-off from key services owing to road flooding — suggest that the impacts of sea-level rise could be more widespread and may begin earlier than anticipated.