News & Views in 2020

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.

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.

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.

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.

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.

Warming can change the vegetation growing season, but the response of autumn phenology to warming remains uncertain. Now research shows warming can lead to autumn greening by delaying leaf senescence, but carbon uptake is constrained by radiation.

The Madden–Julian oscillation causes teleconnections that impact mid-latitudes. Now research predicts dramatic eastward shifts of these impacts in the Pacific–North America region as the climate warms, leading to higher winter rainfall variability along the US West Coast and California in particular.

Pacific Islands are already responding to the adverse effects of climate change, but it is unclear to what extent these responses effectively and sustainably improve local resilience. New research seeks to understand how local beneficiaries evaluate adaptation projects and what this teaches us for future adaptation.

Over the last half of the twentieth century, surface temperature over the South Pole was steady if not slightly cooling, suggesting the high Antarctic interior might be immune to warming. Research now shows a dramatic switch; in the past 30 years, the South Pole has been warming at over three times the global rate.

Migrants arriving in cities must overcome many challenges, including gaining acceptance from established residents. New research from Kenya and Vietnam shows urbanites accept climate hazards as being as legitimate as economic, political or social motivations for rural-to-urban migration.

Ocean acidification is changing the productivity and composition of phytoplankton communities at the base of the aquatic food web. Now a study shows that acidification impairs the swimming ability of flagellated microalgae, suggesting that their capacity to survive is threatened in a high CO₂ world.