Articles in 2020

Monitoring of snowshoe hare (Lepus americanus) cause-specific mortality and behaviour reveals increased risk of predation from coyote (Canis latrans) in shallow snow. This could disrupt the keystone Canada lynx (Lynx canadensis)–hare predator–prey cycle in North American boreal forests.

Using a meta-analysis approach, the authors find robust evidence that environmental factors play a role in explaining migration patterns across countries and over time, but the size of the effects depend on the economic and sociopolitical context, and the environmental factors considered.

The short observational record makes it difficult to gauge how unprecedented recent Arctic warming is. A multi-model large ensemble estimates a new Arctic climate has emerged for sea-ice extent. As the Arctic shifts from a primarily frozen state, temperature and precipitation follow within decades.

Multinational enterprises and their international supply chains can have large carbon footprints, but there is mitigation potential. Global carbon transfer through investment has declined in recent years, and this framework, assigning emissions to the investing country, would inform further action.

Many marine species have migrated towards the poles as water temperatures warm. In contrast, due to changes in the timing of spawning and transport, benthic invertebrates on the Northwest Atlantic continental shelf are pushed into warmer waters where mortality could be higher.

Warming is increasing glacial lakes, and scaling relations show a 48% increase in volume for 1990 to 2018. All measures—area, volume, number—increased, providing water storage but also representing a potential hazard with the risk of outburst floods.

Aerosol transport from South Asia to the Tibetan Plateau (TP) peaks in the pre-monsoon period, but the controlling dynamics remain unclear. Observational analysis shows that low February Arctic sea ice boosts the Asian subtropical jet in April, which can loft aerosols over the Himalayas onto the TP.

Gaps in geographic coverage of species abundance data, especially in the tropics, make determining species’ responses to climate change difficult. Modelling a dataset on global waterbird abundance shows abundance declines in the tropics and increases at higher latitudes when temperatures increase.

Cities have an important role in climate mitigation. Textual analysis techniques and regression modelling show the progress made by over 1,000 cities reporting in the European Covenant of Mayors initiative, active in climate action at the urban level.

Negative emissions technologies are a cornerstone of many mitigation scenarios that limit global warming under 2 °C. Depending on the conditions, bioenergy with carbon capture and storage can provide negative emissions but requires large amounts of land and should be deployed early and with limits.

Climate change impacts on population dynamics will depend on species’ life history strategies. In contrast to short-lived species, longer-lived tropical songbirds reduced reproduction during drought, leading to higher survival and mitigating the effect on long-term population growth.

Negative emissions technologies are essential in scenarios for meeting Paris climate targets. Modelling results show that direct air capture could play an important role with less demand for land yet high energy and water use compared with BECCS and afforestation.

Reforestation has been recently identified as a promising climate mitigation option. In Southeast Asia, 120 million ha of land are biophysically suitable for reforestation. However, financial, land-use and operational factors constrain mitigation potential to a fraction of its total possible value.

Climate change is driving changes in the species composition of plant communities. Analyses of the collection records of thousands of New World plant species reveal widespread increases in the relative abundances of heat-loving species but less consistent responses to changes in precipitation.

Climate models predict that by 2020, 20–55% of the three key ocean basins express an anthropogenic fingerprint of change. The well-ventilated Southern Ocean water masses are particularly sensitive, emerging as early as the 1980–1990s, consistent with observations of change over the past 30 years.

Wide-ranging estimates of the social cost of carbon limit its usefulness in setting carbon prices. Near-term to net zero is an alternative modelling approach that focuses on the prices, combined with other policies, needed to set an economy on a pathway consistent with a net-zero emissions target.

Sea-level rise raises water tables, causing flooding from below and saltwater intrusion. A modelling study predicts that coastal California groundwater flooding will expand 50–130 m inland with 1 m of sea-level rise, with areal flooding extent strongly dependent on topography and drainage capacity.

Arctic climate in the Last Interglacial (LIG)—a warm period 130,000–116,000 years ago—is poorly simulated by modern climate models. A model with improved sea-ice melt-pond physics reproduces LIG Arctic temperatures, suggests an ice-free Arctic during this period and predicts the same by 2035.

Multilevel network modelling shows that social network exposure promotes both adaptive and transformative responses to climate change among Papua New Guinean islanders. Different social–ecological network structures are associated with adaptation versus transformation.

Reduced GHG and air pollutant emissions during the COVID-19 lockdowns resulted in declines in NO_x emissions of up to 30%, causing short-term cooling, while ~20% SO₂ emissions decline countered this for overall minimal temperature effect.