Articles in 2020

Snowmelt runoff is an important source of water for irrigating agricultural crops in high-mountain Asia, Central Asia, western Russia, western US and the southern Andes. Climate change places water resources in these basins at risk, indicating the need to adapt water management.

Costs of achieving climate targets are uncertain. A metamodel estimates the median costs of limiting warming to 2 °C and 1.5 °C to be US$15 trillion and US$30 trillion. Uncertainty in emissions reductions costs dominates at these levels; climate system uncertainty dominates at higher warming levels.

Nitrogen removal occurs primarily through microbially mediated denitrification, which produces the GHG N₂O, and anaerobic ammonium oxidation (anammox), which does not. Warming stimulates denitrification relative to annamox in subtropical sediments, indicating that warming could lead to greater N₂O production.

Concrete production emits high levels of GHGs. It also causes air pollution, with emissions of particulate matter as well as nitrogen and sulfur oxides, which together with GHG emissions cause climate and health damages nearing 75% of the industry value.

Over 60 years of hydrographic data from southeast of Bermuda show the temporal variability of North Atlantic subtropical mode water. Between 2010 and 2018, there was an 86–93% loss of thickness, suggesting weaker production of mode water that is expected to continue with warming.

Changes in the leaf area index alter the distribution of heat and moisture. The change in energy partitioning related to leaf area, increasing latent and decreasing sensible fluxes over the observational period 1982–2016, is moderated by plant functional type and background climate.

Northern peatlands are a significant carbon sink but are vulnerable to decomposition during drought and low water tables. Woody litter added to these ecosystems during high water table conditions leaches polyphenolics that protect carbon stores against decomposition, even during subsequent drought.

Climate change beliefs in the US are politically polarized. Using longitudinal survey data, this study finds that climate change beliefs are less stable over time for Republicans compared with Democrats, suggesting that public beliefs may eventually shift towards broader acceptance.

Exceptionally warm years in 2017–2019 have caused changes in the physical and biological characteristics of the Pacific Arctic Ocean. What these changes mean for the ecosystem and societal consequences will depend on if they are evidence of a transformation or anomalies in the system.

Climate change has led to earlier spring leaf-out in northern temperate and boreal regions. This advanced leaf-out causes warming in the Northern Hemisphere due to the combined effects of water vapour, cloud and snow-albedo feedbacks on the surface energy budget.

Global warming will affect food-web structure and species persistence, and real world data is needed for better prediction. Combining species counts and temperature data from rock pools with dynamic modelling predicts biodiversity increases in arctic to temperate regions and declines in the tropics.

Mountain forest drought can paradoxically increase evapotranspiration (green water), helping vegetation at the expense of runoff (blue water). This is quantified for the 2003 event in the European Alps, highlighting underappreciated vulnerability of blue-water resources to future warmer summers.

Changes in ocean temperature and pH will impact on species, as well as impacting on community interactions. Here warming and acidification cause a clam species to change their feeding mode, with cascading effects for the marine sedimentary food web.

An Earth system model estimates that natural halogens, of marine biotic and abiotic origin, remove about 13% of present-day global tropospheric O₃. Projections suggest this ratio is stable through 2100, with high spatial heterogeneity, despite increasing natural halogens.