Wetter subtropics in a warmer world

A modeling study suggests that weak atmospheric circulation resulting from weak north-south sea surface temperature gradients could explain why the subtropics were wet during the warm Pliocene Epoch, whereas global warming prediction scenarios, which contain comparatively strong atmospheric circulation, predicted subtropical aridification, highlighting the importance of accurately predicting how sea surface temperature gradients might change under global warming scenarios.

Article #17-03421: "Wetter subtropics in a warmer world: Contrasting past and future hydrological cycles," by Natalie J. Burls and Alexey V. Fedorov.

Declining albatross populations

A study from 1972 to 2012 of more than 36,000 albatrosses on Bird Island, South Georgia found that bycatch in fisheries was associated with reduced juvenile and adult survival rates for wandering and black-browed albatrosses and that ongoing changes in climate, such as increased sea surface temperatures and winds, hindered population recovery; further, post-El Niño food shortages were associated with exacerbated negative impact of bycatch for grey-headed albatrosses, indicating the need for a wider adoption of best-practice bycatch mitigation methods and compliance monitoring.

Article #16-18819: "Additive effects of climate and fisheries drive ongoing declines in multiple albatross species," by Deborah Pardo et al.

California land use and climate change mitigation

A study quantifying the potential climate benefits of ecosystem management, restoration, and conservation in California estimates that improving land use across approximately 125,000 hectares every year could negate the temperature rise associated with up to 147 million metric tons of carbon dioxide by 2030 and could contribute up to 17.4% of the emission reductions required to meet California's 2030 climate mitigation target, suggesting that reducing land-based emissions can contribute to climate change mitigation.

Article #17-07811: "Ecosystem management and land conservation can substantially contribute to California's climate mitigation goals," by D. Richard Cameron, David C. Marvin, Jonathan M. Remucal, and Michelle C. Passero.

Climate and nesting in California birds

A study examines links between rising temperatures and nesting in Californian birds. Species respond to climate change by shifting their geographical ranges poleward or upward to remain in their preferred temperature zones, or by shifting the timing of life history events to mirror changes in resource availability. Jacob Socolar and colleagues examined the relationship between temperature and breeding dates for 150 bird species in California's Coast Range and 160 bird species in California's Sierra Nevada. Pairing bird data collected from 1911-1940 with 2003-2010 resurveys performed at the same sites, the authors found that breeding dates for California birds have advanced by approximately 5-12 days. The shift in nesting dates reduced average temperatures during nesting by more than 1 °C--approximately the same magnitude that average regional temperatures have warmed over the same period. Using national nest monitoring data, the authors found that in the early summer across North America, warm temperatures are associated with high nest success in the cold parts of the birds' ranges and low nest success in the warm parts of the birds' ranges. By nesting earlier, California birds are nesting at temperatures similar to those at which they nested a century ago, thus reducing the need for range shifts, according to the authors.

Article #17-05897: "Phenological shifts conserve thermal niches in North American birds and reshape expectations for climate-driven range shifts," by Jacob B. Socolar, Peter N. Epanchin, Steven R. Beissinger, and Morgan W. Tingley.

Assessing Hurricane Harvey-related rainfall in Texas

A study suggests that the annual probability of rainfalls of Hurricane Harvey's magnitude in Texas might increase from 1% during the period from 1981 to 2000 to 18% during the period from 2081 to 2100. Hurricane Harvey produced rainfall averaging approximately 840 mm in the greater Houston metropolitan area. To assess the future likelihood of hurricane-induced rainfall of Harvey's magnitude, Kerry Emanuel embedded a high-resolution, specialized computational hurricane model into coarse-resolution global climate analyses and models. Based on three gridded climate analyses for 1981-2000, the author predicted that Houston would experience a rainfall in excess of 500 mm approximately once every 2000 years; Texas was predicted to experience a rainfall of this magnitude approximately once every 100 years. Six global climate models running Representative Concentration Pathway 8.5, which is a business-as-usual greenhouse gas emissions scenario, predicts that rainfalls greater than 500 mm could occur about once every 100 years by the end of the century in Houston and about once every 5.5 years by the end of the century in Texas. Assuming a linear increase in the frequency of hurricane rains, the models suggest that the current return rate for a rainfall in excess of 500 mm is approximately 325 years for Houston and approximately 16 years for Texas, according to the author.

Article #17-16222: "Assessing the present and future probability of Hurricane Harvey's rainfall," by Kerry Emanuel.

Genomic history of Italian brown bears

Apennine bears are a critically endangered population of approximately 50 Italian brown bears that live in the central Apennine Mountains. Apennine bears (Ursus arctos marsicanus) are separated from other bear populations by several hundred kilometers. Andrea Benazzo et al. (pp. E9589–E9597) explored genomic variation and evolutionary divergence in Apennine bears. The authors sequenced the full genomes of six Apennine bears and six other European brown bears. The authors estimate that Apennine bears were separated from other brown bears during the Neolithic Period, resulting in a 40-fold decline in the Apennine population; Apennine bears may have become isolated due to human expansion and land clearing, the authors suggest. The genetic analysis indicates that Apennine bears are highly inbred with a complete loss of variation in the mitochondrial genome and along long stretches of the nuclear genome. Random drift appears to have fixed several deleterious mutations, but also led to unique features such as small size, distinctive cranial morphology, and reduced aggressiveness, compared with other bears. In combination with a lack of competitors, a nearly vegetarian diet, and low aggressiveness, peaks of high variation in genes associated with the immune and olfactory systems may have helped Apennine bears avoid extinction, according to the authors.

Climate change and Mediterranean fir forests

Based on climate simulations using a business-as-usual emissions scenario, the Mediterranean climate during the late 21st century is predicted to be similar to the driest and hottest periods of the late 20th century that caused forest mortality, according to a study; tree growth estimates based on tree ring data indicate that in response to the changing climate, the growth of some Mediterranean fir species could decrease by 30%, whereas others in moist refugia may benefit from warmer and longer growing seasons, providing insights for the conservation of relict fir populations.

Article #17-08109: "Climate extremes and predicted warming threaten Mediterranean Holocene firs forests refugia," by Raúl Sánchez-Salguero et al.

Epidemics and climate

Reconstruction of climatic patterns, disasters, and human epidemics for large parts of China from AD 1-1911 indicates that long periods of cold and dry conditions were associated with the prevalence of epidemics, likely a result of locust outbreaks and famines; however, the relationship between temperature and epidemics was inconsistent across short time scales, highlighting the scale-dependent impacts of climate change on disease prevalence, according to a study.

Article #17-06470: "Scale-dependent climatic drivers of human epidemics in ancient China," by Huidong Tian et al.

Changing Arctic fish communities

An analysis of 52 fish species in the Barents Sea finds that fish species typical of the boreal region, which are large-bodied species that tend to consume other fish, are replacing Arctic fish species, which are small-bodied species that tend to consume invertebrates at the seabed, findings with potential impacts on Arctic oceanic foodwebs, according to a study.

Article #17-06080: “Climate-driven changes in functional biogeography of Arctic marine fish communities,” by André Frainer et al.

Wave energy and rising sea levels

Geological field surveys and wave models suggest that because sea levels were higher during the Last Interglacial than in modern times waves generated by hurricanes may have been able to transport the massive boulders that rest on a cliff in North Eleuthera in the Bahamas to their current positions during the Last Interglacial, suggesting that rising sea levels could increase the wave-induced erosional energy against cliffs and coastal barriers, according to a study.

Article #17-12433: "Giant boulders and Last Interglacial storm intensity in the North Atlantic," by Alessio Rovere et al.

Population, wellbeing, and climate change mitigation

A study examines the association between climate mitigation decisions and the number of individuals predicted to be affected by climate change in the future. Little is known about the relationship between population growth and the value of reducing greenhouse gas emissions. Noah Scovronick and colleagues used a climate-economic model to study the links between population growth, population ethics, and climate policy. The model suggests that the social cost of carbon dioxide--a measure of the cost of climate change--increases with population growth, increasing more rapidly if humanity's goal is to maximize the total stock of wellbeing--as reflected by happiness, health, and wealth--within a population as opposed to the average level of people's wellbeing. The model indicates that substantial savings in climate mitigation costs can occur annually if society achieves minimal population growth as opposed to intermediate population growth. However, decisions regarding population and climate policy are likely to depend on the ethical approach to valuing population that is adopted, according to the authors.

Article #16-18308: "Impact of population growth and population ethics on climate change mitigation policy," by Noah Scovronick et al.

Tropical thunderstorm potential

Researchers used 12 global warming simulations running the RCP 8.5 emissions scenario to model the amount of daily energy available to thunderstorms during 1981-2000 and during 2081-2100, focusing on the 5% of days with the most potential energy; the models suggest that the average amount of potential energy available on the highest-energy days, and hence the number of damaging thunderstorms, will likely increase over time in the tropics and subtropics.

Article #17-07603: "Increasing potential for intense tropical and subtropical thunderstorms under global warming," by Martin S. Singh, Zhiming Kuang, Eric D. Maloney, Walter M. Hannah, and Brandon O. Wolding.

Nitrous oxide emissions and climate change

Six years of atmospheric sampling in the US Corn Belt revealed that concentrations of nitrous oxide--a greenhouse gas with a global warming potential 300 times that of carbon dioxide--vary considerably year to year, likely the result of temperature and precipitation perturbations; atmospheric modeling indicates that regional nitrous oxide emissions are likely to increase with a warmer and wetter climate, posing a challenge to meeting the climate change mitigation goals outlined at the Paris 2015 Climate Conference, according to a study.

Article #17-04552: "Nitrous oxide emissions are enhanced in a warmer and wetter world," by Timothy J. Griffis et al.

Waiting periods and gun deaths

A study examines links between waiting-period laws for handguns and gun deaths in the United States. Each year, more than 33,000 gun-related deaths occur in the United States. Waiting period laws have the potential to deter gun violence by delaying the acquisition of a firearm. Michael Luca, Deepak Malhotra, and Christopher Poliquin compared the changes in the number of firearm-related deaths in states that enacted handgun waiting periods to the changes in the number of firearm-related deaths in states without waiting period laws from 1970 to 2014; 44 states, including Washington, DC, had waiting periods at some point during this period. The authors find that waiting periods were associated with approximately 36 fewer gun homicides per year in a state with an average number of gun deaths. Waiting periods also were associated with 22-35 fewer gun suicides per year in a state with an average number of gun deaths. Furthermore, the authors conducted a supplemental analysis of the period from 1990 to 1998, during which a federal law--The Brady Act--required 19 states to adopt new handgun waiting periods. The authors found that waiting periods enacted during this time were associated with approximately 39 fewer gun homicides and approximately 17 fewer gun suicides per year for a state with an average number of gun deaths. The authors suggest that the 17 states, including Washington, DC, that had waiting periods as of 2014, likely avoid approximately 750 gun homicides per year with waiting period laws, and that passing waiting period laws in the remaining states might prevent more than 900 additional US gun homicides per year.

Article #16-19896: "Handgun waiting periods reduce gun deaths," by Michael Luca et al.

Climate change and land stewardship

A study suggests that increased land stewardship may be a cost-effective tool for mitigating climate change. Improved stewardship of the land can help limit global warming to below 2 °C above pre-industrial levels, the climate change mitigation goal outlined at the Paris 2015 Climate Conference. Bronson Griscom and colleagues analyzed 20 conservation, restoration, and land management actions, referred to as natural climate solutions (NCS), which can increase carbon storage or avert greenhouse gas emissions across the world's forests, wetlands, grasslands, and agricultural lands. The model projects that the implementation of NCS could negate the temperature rise associated with up to 23.8 Pg of carbon dioxide per year by 2030. The model includes a buffer for food security, fiber security, and biodiversity conservation. The predicted offset in temperature rise is more than 30% higher than previous studies due to the inclusion of additional types of NCS. The authors indicate that NCS could provide 37% of the cost-effective carbon dioxide mitigation needed through 2030, resulting in more than a 66% chance of holding warming below 2 °C. According to the authors, many of the suggested NCS might provide governments, the private sector, and local stakeholders actionable stewardship options to combat climate change, and offer ecosystem services such as improved water filtration, flood buffering, and soil health.

Article #17-10465: "Natural climate solutions," by Bronson W. Griscom et al.

Wolves, dogs, and cooperation

A study suggests that intraspecific cooperation, or cooperation among members of the same species, comes more naturally to wolves than to dogs. Previous studies suggest that domestication may have led dogs to evolve tolerance and cooperation. However, wolves display a greater variety of cooperative behaviors than dogs, including group hunting, pup rearing, and territorial defense. To compare cooperative traits of dogs and wolves, Sarah Marshall-Pescini and colleagues tested how similarly raised wolves and dogs performed at a cooperative rope-pulling test, in which two animals could access food only if both pulled on separate rope ends simultaneously. Regardless of whether the animals had prior training on the apparatus, the wolves outperformed the dogs, with dog pairs succeeding at two of 472 attempts and wolf pairs succeeding at 100 of 416 attempts. Cooperation in wolves was strongest among partners of similar rank and with close social bonds. Furthermore, wolves were more likely to simultaneously manipulate the apparatus than dogs, an action that appeared to help the wolves grasp the necessary coordinated behavior. The authors suggest that dogs may avoid simultaneously pulling on the ropes to avoid conflict over a coveted resource. Rather than supporting the hypothesis that dogs evolved greater cooperative inclinations than wolves, the study suggests that the different social behaviors of the two species influence their capacity for cooperation and communication, according to the authors.

Article #17-09027: "Importance of a species' socioecology: Wolves outperform dogs in a conspecific cooperation task," by Sarah Marshall-Pescini, Jonas F. L. Schwarz, Inga Kostelnik, Zsófia Virányi, and Friederike Range.

Coal and potential global glaciation

Climate model simulations indicate that global glaciation could have occurred during the early Permian, which directly followed the formation of the bulk of Earth's coal deposits, if atmospheric carbon dioxide concentrations had decreased to approximately 37.5 ppm; the study suggests that the formation of Earth's coal deposits may have almost led to a global glaciation during the early Permian.

Article #17-12062: "Formation of most of our coal brought Earth close to global glaciation," by Georg Feulner.

Open-ocean wind farms

A study suggests that wind farms in open ocean environments may be able to sustain higher electricity generation rates than wind farms on land. Wind turbines on wind farms continuously convert kinetic energy from surface winds into electricity. By removing kinetic energy from wind, turbines reduce wind speed, constraining the rate of electricity generation in wind farms. Several past studies indicate that the rate of electricity generation for large wind farms on land may be limited to approximately 1.5 watts per square meter. Anna Possner and Ken Caldeira modeled the electricity generation rates of potential wind farms in open-ocean environments. The authors identified the North Atlantic as a region where annual electricity generation rates could average more than 6 watts per square meter, despite seasonal fluctuations. Furthermore, the simulations suggest that, in certain areas of the ocean, atmospheric circulation patterns over the ocean allow wind farms to tap into the kinetic energy reservoir of the entire overlying troposphere, as opposed to the limited kinetic energy available at the ocean surface, thereby sustaining rates of wind power generation three times higher than those observed on land. According to the authors, if commercial-scale open-ocean wind turbines could be produced, open-ocean wind farms that are spread across approximately 3 million square kilometers could meet the current annual global energy demand of 18 terawatts.

Article #17-05710: "Geophysical potential for wind energy over the open oceans," by Anna Possner and Ken Caldeira.

Black carbon deposits on birds

Using bird specimens from museums, researchers estimate black carbon aerosol concentrations during the early industrial period, according to a study. Combustion of organic matter, such as coal, generates atmospheric black carbon, which contributes to anthropogenic climate change. Estimates of early industrial emissions of black carbon are inexact, partly because black carbon sampling was uncommon prior to the mid-1950s. Using photometric reflectance data from museum specimens of birds collected from 1880 to 2015, Shane DuBay and Carl Fuldner measured the relative concentration of atmospheric black carbon deposited on more than 1,000 birds, capturing concentrations from the year each bird was collected. The birds were originally collected within the US Manufacturing Belt, which was historically reliant on coal-burning industries and includes Chicago, Detroit, and Pittsburgh. The authors found that regional black carbon concentrations peaked during the first decade of the 20th century and were linked with coal consumption through midcentury. After 1960, black carbon concentrations and coal consumption became decoupled, likely due to more efficient coal burning, increased availability of other fuels, and regulations on coal consumption. Furthermore, the authors found that black carbon concentrations were higher than previous estimates for 1880-1910, but were consistent with previous estimates after 1910. According to the authors, the past climate-forcing effects of black carbon may be underestimated.

Article #17-10239: "Bird specimens track 135 years of atmospheric black carbon and environmental policy," by Shane G. DuBay and Carl C. Fuldner.

Slow-growing subseafloor microbes

Researchers incubated Miocene-aged coal and shale samples collected from 2 kilometers below the seafloor near Japan and found that the microbial community in the samples could metabolize methylated substrates at 45 °C and doubled at a rate that ranged from several months to more than 100 years, representing a population of extremely slow-growing heterotrophs that can use a range of carbon and nitrogen sources.

Article #17-07525: “Methyl-compound use and slow growth characterize microbial life in 2-km-deep subseafloor coal and shale beds,” by Elizabeth Trembath-Reichert et al.