Global warming mitigation strategies

According to a Perspective, human efforts toward carbon net neutrality and the reduction of non-CO2 pollutants by 2020 is estimated to result in a 50% probability of remaining below 1.5 °C  increase in global average temperature since preindustrial times; further, removal of 1 trillion tons of atmospheric CO2 before 2100 through carbon extraction and sequestration might be needed to increase the probability to 95%, thus limiting CO2 emissions during the span from preindustrial times to 2100 to 2.2 trillion tons and generating a cooling trend at 2100.

Article #16-18481: “Well below 2°C: Mitigation strategies for avoiding dangerous to catastrophic climate changes,” by Yangyang Xu and Veerabhadran Ramanathan.

 

Number of Amazonian tree species

A taxonomically verified checklist of all published Amazonian plant species identified 6,727 tree species, indicating that the total number of Amazonian tree species is at the low end of model estimates and providing a foundation for future research on the ecology and evolution of one of the most species-rich regions on Earth.

Article #17-06756: "Amazon plant diversity revealed by a taxonomically verified species list," by Domingos Cardoso et al.

Misperception of racial economic equality

A series of studies including 1,377 White and Black Americans from the top and bottom of the national income distribution reports that study participants generally overestimated society's progress toward racial economic equality, and that the accuracy with which White Americans estimated Black-White economic equality increased if participants were primed to imagine a United States where race-based discrimination existed, compared with when participants were not primed, suggesting the existence of unfounded optimism regarding societal race-based economic equality in American society.

Article #17-07719: "Americans misperceive racial economic equality," by Michael W. Kraus, Julian M. Rucker, and Jennifer A. Richeson.

Vulnerability of vertebrates

An analysis of 27,647 vertebrate species finds an association between body size and extinction risk, and indicates that the lightest and heaviest vertebrate species experience the highest risks of extinction, and that the heaviest vertebrates are most at risk of direct killing by humans, whereas the lightest vertebrates are most at risk of habitat degradation, suggesting that anthropogenic activities could reduce the size distribution of the world's vertebrates.

Article #17-02078: "Extinction risk is most acute for the world's largest and smallest vertebrates," by William J. Ripple et al.

Color naming across languages

A study finds that linguistic descriptions of colors are related to the usefulness of colors in individual cultures. The question of whether color categories are universal or shaped by culture remains unsettled. Bevil Conway, Edward Gibson, and colleagues analyzed color-naming data from 110 languages, and found that colors generally considered "warm," such as red, yellow, and orange, were easier to precisely communicate than colors generally considered "cool," such as blue and green, across all languages. The authors also conducted color-naming studies with more than 200 people, ages 16-78, who speak English, Bolivian-Spanish, or Tsimane', a language spoken by the nonindustrialized, indigenous Amazonian Tsimane' people. The authors found that the Tsimane' were less likely than the English or Spanish speakers to use color terms when describing familiar objects, and that the Tsimane' system of colors was less informative than those of the other cultures, suggesting that differences in color categorization between languages may reflect differences in the usefulness of color to individual cultures. The Tsimane' increased their use of color vocabulary when describing artificially colored objects, compared with natural ones, suggesting that industrialization promotes color usefulness. According to the authors, the study provides insights into the variability in the number of color terms across languages.

Article #16-19666: "Color naming across languages reflects color use," by Edward Gibson et al.

Multi-drug-resistant organisms in nursing homes

Based on a study of 234 nursing home residents, on average 74 years of age, a study finds that the use of antibiotics was linked to the primary colonization of multi-drug-resistant organisms (MDROs), which in turn increased the potential for colonization and infection by other MDROs, suggesting that interactions among MDROs should be considered when designing strategies to reduce their spread.

Article #17-10235: “Network of microbial and antibiotic interactions drive colonization and infection with multidrug-resistant organisms,” by Joyce Wang, Betsy Foxman, Lona Mody, and Evan S. Snitkin.

Global shift in plant water use efficiency

A modeling study suggests that the decrease in the carbon isotopic ratio (13C/12C) of atmospheric carbon dioxide (CO2) over the past few decades has been slower than that predicted based on fossil-fuel derived CO2 emissions, suggesting a shift in plant leaf traits in response to increased atmospheric CO2 that reflects increased efficiency of water use by plants relative to the past.

Article #16-19240: "Atmospheric evidence for a global secular increase in carbon isotopic discrimination of land photosynthesis," by Ralph F. Keeling et al.

Coral resilience on Great Barrier Reef

A comparison of modern and dead coral assemblages found that the mortality of branching Acropora corals on the central Great Barrier Reef is frequently linked to discrete disturbances during the early to mid-20th century, and that Acropora corals represented less than 5% of living corals on the reef surface from the late 1990s to 2014, suggesting that the resilience of this formerly dominant reef-building coral has decreased at a regional scale.

Article #17-05351: "U-Th dating reveals regional-scale decline of branching Acropora corals on the Great Barrier Reef over the past century," by Tara R. Clark et al.

Synchronous eruptions and deglaciation in Southern Hemisphere

Analyses of Antarctic ice cores indicate that an approximately 192-year series of halogen-rich volcanic eruptions occurred approximately 17,700 years ago and can be attributed to Mount Takahe in West Antarctica; the authors suggest that the halogen may have depleted stratospheric ozone concentrations over Antarctica, triggering a nearly synchronous deglaciation in the Southern Hemisphere that has been previously documented in paleoclimate records.

Article #17-05595: "Synchronous volcanic eruptions and abrupt climate change ?17.7 ka plausibly linked by stratospheric ozone depletion," by Joseph R. McConnell et al.

Corn supply chains in the United States

Researchers report a transportation model that tracks the distribution of corn from the county of production in the United States to primary processing of corn-fed animals and ethanol products; the study estimates the environmental impacts of corn production in all contiguous US counties and for various corn supply networks, and finds that the environmental impacts of corn production differ across industry and firm-level supply chains.

Article #17-03793: "Subnational mobility and consumption-based environmental accounting of US corn in animal protein and ethanol supply chains," by Timothy M. Smith et al.

Coastal flood risk and rising sea levels

A flood hazard assessment that accounts for the compounding impacts of both rising river flow and ocean water levels predicts shorter intervals between floods for three US coastal cities than an assessment that considers only one driving factor for flooding, and further analyses indicates that compound effects are likely to increase coastal flood risk as sea levels rise in the future, according to a study.

Article #16-20325: "Compounding effects of sea level rise and fluvial flooding," by Hamed R. Moftakhari, Gianfausto Salvadori, Amir AghaKouchak, Brett F. Sanders, and Richard A. Matthew.

Forest mortality risk and climate change

A soil-plant-atmosphere model for 2050-2069 predicts that changes in precipitation and air temperature are likely to lead to increased plant mortality risk within 13 temperate and tropical forest biomes across the globe; however, increases in specific humidity and carbon dioxide concentrations are likely to partially offset the rising mortality risk, according to a study.

Article #17-04811: "Increasing atmospheric humidity and CO2 concentration alleviate forest mortality risk," by Yanlan Liu et al.

European electricity consumption under climate change

A study estimates future electricity consumption across Europe under projected climate change. To examine the future of Europe's electricity consumption patterns under anthropogenic climate change, Leonie Wenz and colleagues analyzed high-frequency temperature and electricity use data from 35 European countries between 2006 and 2012, and projected the countries' electricity consumption for the period from 2013 to 2099. The authors found that at the country level daily peak electricity use was generally low when daily maximum temperatures were approximately 22 °C, and increased if daily maximum temperatures either rose or fell. To make electricity use projections, the authors assumed that rising temperatures are likely to lead Europeans living in currently cool climates to adapt to higher temperatures through practices such as installing air conditioners. Based on current electricity use patterns from European countries with warm climates, the authors predict that average daily peak usage and electricity consumption are likely to decrease in Northern Europe and largely increase in Southern and Western Europe under future warming. Furthermore, the authors found that consumption in many European countries is likely to peak in summer instead of winter by the end of the century. According to the authors, the projected seasonal and geographic shifts in consumption patterns are likely to affect transmission infrastructure, peak-generating capacity, and storage requirements.

Article #17-04339: "North-south polarization of European electricity consumption under future warming," by Leonie Wenz, Anders Levermann, and Maximilian Auffhammer.

Soil carbon loss since advent of farming

A global soil model based on historical land use data estimates that agricultural land use has resulted in the loss of 133 Pg of carbon from the top 2 meters of soil over the past 12,000 years, and indicates hotspots of soil carbon loss that are often associated with major cropping or grazing regions, suggesting the existence of identifiable regions that could be targeted for soil carbon restoration.

Article #17-06103: "Soil carbon debt of 12,000 years of human land use," by Jonathan Sanderman, Tomislav Hengl, and Gregory J. Fiske.

Forest fire activity in southern South America

Tree-ring fire scars from 1,767 trees in southern South America reveal a coupling of drought that is driven by the Southern Annular Mode--the north-south movement of winds that circle Antarctica--and regional fire activity at yearly and multidecadal timescales from 1665-1995, suggesting that under current and projected climate conditions in southern South America, SAM-mediated droughts are likely to drive widespread wildfire activity in the 21st century, according to a study.

Article #17-05168: "Southern Annular Mode drives multicentury wildfire activity in southern South America," by Andrés Holz et al.

Agricultural yields and rising temperatures

Researchers report links between rising temperatures and global yields of major crops. Humans rely on wheat, rice, maize, and soybeans for two-thirds of their caloric intake. The effect of climate change on the yields of the four crops remains uncertain. Senthold Asseng and colleagues assessed the impact of increasing temperatures on wheat, rice, maize, and soybean yields by performing a meta-analysis of more than 70 studies. The meta-analysis included studies that incorporated analytical methods such as process-based model simulations of yield response to temperature changes at the global and local scale, statistical regression models based on historical weather and yield data, and artificial field warming experiments. All four methods suggest that increasing temperatures are likely to have a negative effect on the global yields of wheat, rice, and maize. Without carbon dioxide fertilization, farming adaptations, or genetic improvement, each degree Celsius increase in global mean temperature is estimated to reduce average global yields of wheat by 6.0%, rice by 3.2%, and maize by 7.4%.  Estimates of soybean yields did not change significantly. The estimated effect of rising temperatures on yield varied greatly across crops and geographical areas, with yields increasing for some crops at some locations. According to the authors, the analyses provide insights into the development of crop-specific and region-specific adaptation strategies for ensuring global food security.

Article #17-01762: "Temperature increase reduces global yields of major crops in four independent estimates," by Chuang Zhao et al.

Climate and feeding behavior in lake trout

An 11-year study of lake trout (Salvelinus namaycush), a cold-water fish, conducted at the Canadian International Institute for Sustainable Development Experimental Lakes Area found that during warmer years lake trout had reduced access to shallow water habitats, leading to a diet of relatively smaller prey and reduced growth, compared with cooler years, suggesting a link between climate change and top predators' feeding behavior and energy acquisition.

Article #17-02584: "Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator," by Matthew M. Guzzo, Paul Blanchfield, and Michael Rennie.

Volcanic degassing and oxygen rise

A study of basalt cores from Hawaii’s Mauna Kea volcano finds that Mauna Kea magmas that had experienced the least amount of volcanic degassing were more oxidized than midocean ridge basalt magmas, and that degassing reduced the oxidation state of Mauna Kea magmas; modeling suggests that, if the Mauna Kea degassing trend were broadly applied to basaltic systems, degassing basalts would not explain the rise of oxygen at the end of the Archean eon.

Article #16-19527: “Redox variations in Mauna Kea lavas, the oxygen fugacity of the Hawaiian plume, and the role of volcanic gases in Earth’s oxygenation,” by Maryjo Brounce, Edward Stolper, and John Eiler.

Cool roofs in Southern California

Weather and air quality models for California’s South Coast Air Basin indicate that widespread installation of roofing materials with enhanced solar reflectance that are in line with building energy efficiency standards could decrease daily maximum temperatures, but such installations could have previously unrecognized negative implications for fine atmospheric particulate matter and ozone concentrations, findings that could inform building efficiency standards.

Article #17-03560: “Air-quality implications of widespread adoption of cool roofs on ozone and particulate matter in southern California,” by Scott A. Epstein et al.

Maize domestication in Central America

A study examines maize domestication in the Honduran highlands. Archeological and genetic evidence indicates that the domestication of maize (Zea mays ssp. mays) began in the Balsas region of Mexico by approximately 9,000 years ago. However, when maize became a staple grain in the Americas remains unclear. Douglas Kennett and colleagues report morphological characteristics of maize cobs found in the El Gigante rockshelter in western Honduras, which is outside the natural geographic range of Zea mays ssp. parviglumis, the wild predecessor of maize. Radiocarbon dates from 88 El Gigante botanical samples suggest that the rockshelter was used intermittently during the last 11,000 years. Direct radiocarbon dating of 37 cobs revealed that maize was abundant in deposits largely during two time periods: 4,340-4,020 years ago and 2,350-980 years ago. The earliest cobs had 10-14 rows, and the maize dating between 2,350 and 980 years ago exhibited increased cob and kernel size, compared with the older cobs. The data indicate that productive varieties of maize existed in Central America by approximately 4,300 years ago. Reproductive isolation outside the range of the wild predecessor may have aided the development of productive staple maize varieties, according to the authors.

Article #17-05052: “High-precision chronology for Central American maize diversification from El Gigante rockshelter, Honduras,” by Douglas J. Kennett et al.