Articles in 2020

Global emissions could decrease 3.9–5.6% over 5 years due to COVID-19, and the interconnected economy means lockdown-related declines reach beyond borders. As countries look to stimulate their economies, how fiscal incentives are allocated and invested will determine longer-term emission changes.

GHG mitigation is not likely to be detectable in global mean temperature before mid-century. However, a simple climate emulator and an Earth system model ensemble suggest that strong mitigation greatly decreases the likelihood of high rates of 20-year warming over the next two decades.

The strength of a positive Indian Ocean Dipole (pIOD) is set by sea surface temperature gradient across the equatorial Indian Ocean. Modelling shows warming will increase strong pIODs but decrease moderate pIODs, as faster surface warming in the west sets up conducive conditions for the strong events.

An increase in ocean transport from the North Atlantic into the Nordic Seas and Arctic Ocean is warming the region. Observations from 1993 to 2016 show a significant increase in heat transport after 2001, with the heat being transported over the Greenland–Scotland Ridge.

Analysis of ectotherm thermal death curves in the context of both challenge intensity and duration shows that smaller animals exhibit higher tolerance to acute stress, but lower tolerance to chronic stress. The size-dependent impact provides one explanation for warming-related reductions in animal size.

Global trade and transport depend on the resilience of the ports sector. Multi-hazard operational risks are estimated for 2,013 ports under historical climate and future warming; of the marine and atmospheric hazards considered, coastal flooding, wave overtopping and heat stress increase risk most.

Hydrological modelling is combined with soil moisture estimates to quantify climate change impacts on inland Ramsar wetlands. Net global changes are estimated to be modest, but individual sites with area reductions over 10% are projected to increase 19–243% by 2100, depending on emissions scenario.

The east–west gradient in equatorial Pacific sea surface temperature has strengthened, but models suggest the opposite in past and future climates. Model ensembles show that the observed trend can arise from internal variability but their gradient weakens in the long term, causing more climate warming.

Spring phenology is influenced by chilling, forcing and photoperiod cues; the phenological response to warming from anthropogenic climate change may be slowed by chilling or photoperiod. Plant species respond to all cues in experiments but under environmental conditions, forcing predominates.

The biological pump sequesters carbon to the deep ocean. Ocean acidification, through impacts on plankton and food-web structure, is shown to alter the carbon-to-nitrogen ratio of organic material export, with heterotrophic processes playing a key role.

Carbon emissions from fires are generally modelled and predicted from fire weather and climate. Fuel availability drives carbon emissions more strongly than fire weather in boreal forests, highlighting the importance of ecological dynamics for fire–climate feedbacks.

Mass field testing of heat tolerance in 1,973 cultivars of sweet potato (Ipomoea batatas) from 50 countries identifies tolerant cultivars and reveals tolerance-predictive traits for breeding consideration. The work highlights the role of intraspecific diversity for future crop resilience.

Dust deposition in high-mountain Asia lowers snow albedo and hastens melt. Satellite data and models show that dust arrives via transport in elevated aerosol layers and outweighs black carbon impacts at high altitudes, suggesting a growing importance of dust on snowmelt as snowlines rise with warming.

Education increases political polarization on climate change beliefs in the US. Here the authors find that this effect does not generalize to other contexts. Across 64 countries, education has positive effects on climate change beliefs, and interactions with ideology are more nuanced and contextual.

Electric vehicles (EV) are often considered as the best chance for reducing light-duty transport emissions. Analysis of US policies shows that required emission reductions exceed feasible EV deployment, and technology alongside behaviour change is needed.

Seawater properties—temperature, salinity and density—cause stratification of the water column, limiting vertical exchange. Considering down to 2,000 m, ocean stratification is shown to have increased ~5.3% since 1960, with ~71% of the change occurring in the upper 200 m primarily from warming.

Winter conditions are the strongest environmental variable relating to fine-scale patterns in tundra vegetation. Vascular plants, lichens and bryophytes nonetheless show complex responses across environmental gradients, highlighting the importance of local heterogeneity.

Replicated bromeliad microecosystems were used to examine warming-induced community shifts and changes to tadpole gut microbiome. Tadpole growth was more strongly associated with cascading effects of warming on gut dysbiosis than with direct warming effects or indirect effects on food resources.

High warming rates may exceed an organism’s ability to track their thermal habitats. The velocity of climate change in inland standing waters will increase markedly under future warming, making freshwater species particularly vulnerable because their habitat is fragmented in the landscape.

Introducing carbon prices is considered central to climate change mitigation. This study shows that publics prefer constant carbon cost schedules rather than those that gradually increase, even when average costs are the same, because of a desire to smooth consumption over time.