Reviews & Analysis

The SSP–RCP scenario framework has been an important component of physical, social and integrated climate change research for the past decade. This Perspective reviews the successes of the framework and the challenges it faces, and provides suggestions for improvement moving forward.

Body sizes have been declining in response to climate change, but an expected relationship between size and the hot temperatures organisms can tolerate has eluded detection. Now, research shows how body size and the duration of exposure to hot temperatures interact to determine the onset and consequences of thermal stress.

The shift to data-driven urban climate governance alters accountability. This Review examines critically the drivers of the shift—standardization, transparency and capacity building—and how best to achieve equitable climate mitigation outcomes within this context.

The Arctic is warming and undergoing rapid ice loss. This Perspective considers how changes in sea ice will impact the biogeochemistry and associated ecosystems of the region while calling for more observations to improve our understanding of this complex system.

Increasing fire frequency and severity may shift boreal forests from carbon sinks to carbon sources and amplify climate warming. Analysis indicates that fuel characteristics are important drivers of wildfire carbon emissions across a broad range of North America’s boreal forest.

Agricultural systems are vulnerable to climate change, and global reservoirs of plant genetic diversity are proving to be a valuable means of crop adaptation. A study now shows that production of sweet potato is at risk from extreme heat events, but a few tolerant cultivars can still thrive and potentially provide climate resilience.

Dust and black carbon deposition in high-mountain Asia darkens snow and ice, increases sunlight absorption and causes melt — a reinforcing feedback. Now research shows the increasing importance of dust over black carbon at higher altitude, and the sensitivity of aerosol transport and delivery to Arctic sea-ice melt.

Winter conditions have typically been downplayed or oversimplified in past estimations of terrestrial Arctic vegetation shifts in relation to climate change. A study now demonstrates the importance of fine-scale variation in winter temperature in explaining the composition and diversity of Arctic plant communities.

While large-scale climate-associated changes are becoming increasingly visible, our understanding of changes in the microbial world remains limited. Now a study takes advantage of a tropical microecosystem to disentangle the direct and indirect impacts of increased temperatures on the microbiomes of animals.

Ongoing Arctic changes are impacting phytoplankton. This Review considers recent primary productivity trends and the environmental drivers, as well as how these are changing, that drive phytoplankton diversity in the region.

Raising the cost of carbon is critical for effective climate policy, but is politically challenging because the public are averse to costs. Conventional wisdom suggests this could be addressed by giving the public time to adjust by gradually increasing costs. However, new research shows that the public actually prefers a constant cost curve.

Theory and observation suggest that populations of long-lived organisms fare worse than short-lived counterparts when submitted to increased mortality. Now, research shows that longevity affords the prospect of reducing mortality by breeding less under stress.

As road transport emissions are set to grow, stronger policy mixes are needed to reach mitigation goals. This Perspective considers the evidence for several policy types—strong regulation, pricing and reduced travel—and the best combination to reduce emissions for passenger and freight vehicles.

Gravity-based estimates of mass change have been extended by the recently launched GRACE Follow-On Satellites. The satellite record, combined with regional climate models, reveals that the Greenland Ice Sheet had lower mass loss in 2017–2018, only to return to a record-breaking mass loss in the summer of 2019.

The response of coastal groundwater to sea-level rise is largely unknown. Groundwater modelling along the California coast — accounting for complex topography and its interaction with rivers, streams and tributaries — shows that the area at risk from rising groundwater tables extends beyond that inundated by sea-level rise alone.

More intense precipitation is an expected consequence of anthropogenic climate change. Now research quantifies the effect of more concentrated rainfall on American agriculture.

In recent decades, the Arctic has warmed at over twice the global rate. This Perspective places these trends into the context of abrupt Dansgaard–Oeschger warming events in the palaeoclimate record, arguing that the contemporary Arctic is undergoing comparably abrupt climate change.

International trade plays an important role in ensuring the resilience of the global food system. Now research suggests a further reduction in trade barriers could alleviate the impacts of climate change on hunger risk.

Climate change will lead to geographic shifts in global habitats, forcing plant populations to migrate or perish. Model-based analysis for wind-dispersed plants under future climate conditions show the importance of considering both ‘where to go’, in terms of the desired temperature, and ‘how to get there’, in terms of wind speed and direction.

Over the last two decades, many countries have passed laws addressing climate change and related areas. Research now shows that these laws make a difference to emission outcomes, but the pathways of impact require further research.