Taking the heat
Long-Term Ambient Temperature and Externalizing Behaviors in Adolescents
Diana Younan et al.
American Journal of Epidemiology, forthcoming
Abstract:
The climate-violence relationship has been debated for decades, and yet most of the supportive evidence came from ecological or cross-sectional analyses with very limited long-term exposure data. We conducted an individual-level, longitudinal study to investigate the association between ambient temperature and externalizing behaviors of urban-dwelling adolescents. Participants (n = 1,287) of the Risk Factors for Antisocial Behavior Study were examined in 2000–2012 (aged 9–18 years) with repeated assessments of their externalizing behaviors (aggression; delinquency). Ambient temperature data were obtained from the local Meteorological Information System. In adjusted multi-level models, aggressive behaviors significantly increased with rising average temperatures (per 1°C-increment) in preceding 1–3 years (β = 0.23, 95% CI: 0.00, 0.46; β = 0.35, 95% CI: 0.06, 0.63; β = 0.41, 95% CI: 0.08, 0.74; respectively), equivalent to 1.5–3 years of delay in age-related behavioral maturation. These associations were slightly stronger among girls and families of lower socioeconomic status, but greatly diminished in neighborhoods with higher greenspace. No significant associations were found with delinquency. Our study provides the first individual-level epidemiologic evidence supporting the adverse association of long-term ambient temperature and aggression. Similar approaches to studying meteorology and violent crimes may further inform scientific debates on climate change and collective violence.
Heat and Learning
Joshua Goodman et al.
NBER Working Paper, May 2018
Abstract:
We provide the first evidence that cumulative heat exposure inhibits cognitive skill development and that school air conditioning can mitigate this effect. Student fixed effects models using 10 million PSAT-takers show that hotter school days in the year prior to the test reduce learning, with extreme heat being particularly damaging and larger effects for low income and minority students. Weekend and summer heat has little impact and the effect is not explained by pollution or local economic shocks, suggesting heat directly reduces the productivity of learning inputs. New data providing the first measures of school-level air conditioning penetration across the US suggest such infrastructure almost entirely offsets these effects. Without air conditioning, each 1°F increase in school year temperature reduces the amount learned that year by one percent. Our estimates imply that the benefits of school air conditioning likely outweigh the costs in most of the US, particularly given future predicted climate change.
Experimental effects of climate messages vary geographically
Baobao Zhang et al.
Nature Climate Change, May 2018, Pages 370–374
Abstract:
Social science scholars routinely evaluate the efficacy of diverse climate frames using local convenience or nationally representative samples. For example, previous research has focused on communicating the scientific consensus on climate change, which has been identified as a ‘gateway’ cognition to other key beliefs about the issue. Importantly, although these efforts reveal average public responsiveness to particular climate frames, they do not describe variation in message effectiveness at the spatial and political scales relevant for climate policymaking. Here we use a small-area estimation method to map geographical variation in public responsiveness to information about the scientific consensus as part of a large-scale randomized national experiment (n = 6,301). Our survey experiment finds that, on average, public perception of the consensus increases by 16 percentage points after message exposure. However, substantial spatial variation exists across the United States at state and local scales. Crucially, responsiveness is highest in more conservative parts of the country, leading to national convergence in perceptions of the climate science consensus across diverse political geographies. These findings not only advance a geographical understanding of how the public engages with information about scientific agreement, but will also prove useful for policymakers, practitioners and scientists engaged in climate change mitigation and adaptation.
Increasing precipitation volatility in twenty-first-century California
Daniel Swain et al.
Nature Climate Change, May 2018, Pages 427–433
Abstract:
Mediterranean climate regimes are particularly susceptible to rapid shifts between drought and flood—of which, California’s rapid transition from record multi-year dryness between 2012 and 2016 to extreme wetness during the 2016–2017 winter provides a dramatic example. Projected future changes in such dry-to-wet events, however, remain inadequately quantified, which we investigate here using the Community Earth System Model Large Ensemble of climate model simulations. Anthropogenic forcing is found to yield large twenty-first-century increases in the frequency of wet extremes, including a more than threefold increase in sub-seasonal events comparable to California’s ‘Great Flood of 1862’. Smaller but statistically robust increases in dry extremes are also apparent. As a consequence, a 25% to 100% increase in extreme dry-to-wet precipitation events is projected, despite only modest changes in mean precipitation. Such hydrological cycle intensification would seriously challenge California’s existing water storage, conveyance and flood control infrastructure.
Antibiotic resistance increases with local temperature
Derek MacFadden et al.
Nature Climate Change, June 2018, Pages 510–514
Abstract:
Bacteria that cause infections in humans can develop or acquire resistance to antibiotics commonly used against them. Antimicrobial resistance (in bacteria and other microbes) causes significant morbidity worldwide, and some estimates indicate the attributable mortality could reach up to 10 million by 2050. Antibiotic resistance in bacteria is believed to develop largely under the selective pressure of antibiotic use; however, other factors may contribute to population level increases in antibiotic resistance. We explored the role of climate (temperature) and additional factors on the distribution of antibiotic resistance across the United States, and here we show that increasing local temperature as well as population density are associated with increasing antibiotic resistance (percent resistant) in common pathogens. We found that an increase in temperature of 10 °C across regions was associated with an increases in antibiotic resistance of 4.2%, 2.2%, and 2.7% for the common pathogens Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The associations between temperature and antibiotic resistance in this ecological study are consistent across most classes of antibiotics and pathogens and may be strengthening over time. These findings suggest that current forecasts of the burden of antibiotic resistance could be significant underestimates in the face of a growing population and climate change.
Global Melting? The Economics of Disintegration of the Greenland Ice Sheet
William Nordhaus
NBER Working Paper, May 2018
Abstract:
Concerns about the impact on large-scale earth systems have taken center stage in the scientific and economic analysis of climate change. The present study analyzes the economic impact of a potential disintegration of the Greenland Ice Sheet (GIS). The method is to combine a small geophysical model of the GIS with the DICE integrated assessment model. The result shows that the GIS is likely to disappear over the next millennium or so without climate policy, but an active climate policy may prevent the GIS from crossing the threshold of irreversibility. Additionally, the study estimates the impact of the GIS on the social cost of carbon (SCC) and finds that adding GIS dynamics would add less than 5% to the SCC under alternative discount rates and estimates of the GIS dynamics. Simulations of geo-engineering options indicate that the dynamics of disintegration and rebuilding are extremely asymmetric, implying that GIS disintegration should be treated as irreversible.
Clean vehicles as an enabler for a clean electricity grid
Jonathan Coignard et al.
Environmental Research Letters, May 2018
Abstract:
California has issued ambitious targets to decarbonize transportation through the deployment of electric vehicles (EVs), and to decarbonize the electricity grid through the expansion of both renewable generation and energy storage. These parallel efforts can provide an untapped synergistic opportunity for clean transportation to be an enabler for a clean electricity grid. To quantify this potential, we forecast the hourly system-wide balancing problems arising out to 2025 as more renewables are deployed and load continues to grow. We then quantify the system-wide balancing benefits from EVs modulating the charging or discharging of their batteries to mitigate renewable intermittency, without compromising the mobility needs of drivers. Our results show that with its EV deployment target and with only one-way charging control of EVs, California can achieve much of the same benefit of its Storage Mandate for mitigating renewable intermittency, but at a small fraction of the cost. Moreover, EVs provide many times these benefits if two-way charging control becomes widely available. Thus, EVs support the state's renewable integration targets while avoiding much of the tremendous capital investment of stationary storage that can instead be applied towards further deployment of clean vehicles.
Hurricane Harvey links to Ocean Heat Content and Climate Change Adaptation
Kevin Trenberth et al.
Earth's Future, forthcoming
Abstract:
While hurricanes occur naturally, human‐caused climate change is supercharging them and exacerbating the risk of major damage. Here, using ocean and atmosphere observations, we demonstrate links between increased upper ocean heat content due to global warming with the extreme rainfalls from recent hurricanes. Hurricane Harvey provides an excellent case study as it was isolated in space and time. We show that prior to the beginning of northern summer of 2017, ocean heat content was the highest on record both globally and in the Gulf of Mexico, but the latter sharply decreased with hurricane Harvey via ocean evaporative cooling. The lost ocean heat was realized in the atmosphere as moisture, and then as latent heat in record‐breaking heavy rainfalls. Accordingly, record high ocean heat values not only increased the fuel available to sustain and intensify Harvey, but also increased its flooding rains on land. Harvey could not have produced so much rain without human‐induced climate change. Results have implications for the role of hurricanes in climate. Proactive planning for the consequences of human‐caused climate change is not happening in many vulnerable areas, making the disasters much worse.
Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries
Chunwu Zhu et al.
Science Advances, May 2018
Abstract:
Declines of protein and minerals essential for humans, including iron and zinc, have been reported for crops in response to rising atmospheric carbon dioxide concentration, [CO2]. For the current century, estimates of the potential human health impact of these declines range from 138 million to 1.4 billion, depending on the nutrient. However, changes in plant-based vitamin content in response to [CO2] have not been elucidated. Inclusion of vitamin information would substantially improve estimates of health risks. Among crop species, rice is the primary food source for more than 2 billion people. We used multiyear, multilocation in situ FACE (free-air CO2 enrichment) experiments for 18 genetically diverse rice lines, including Japonica, Indica, and hybrids currently grown throughout Asia. We report for the first time the integrated nutritional impact of those changes (protein, micronutrients, and vitamins) for the 10 countries that consume the most rice as part of their daily caloric supply. Whereas our results confirm the declines in protein, iron, and zinc, we also find consistent declines in vitamins B1, B2, B5, and B9 and, conversely, an increase in vitamin E. A strong correlation between the impacts of elevated [CO2] on vitamin content based on the molecular fraction of nitrogen within the vitamin was observed. Finally, potential health risks associated with anticipated CO2-induced deficits of protein, minerals, and vitamins in rice were correlated to the lowest overall gross domestic product per capita for the highest rice-consuming countries, suggesting potential consequences for a global population of approximately 600 million.
Concurrent increases in wet and dry extremes projected in Texas and combined effects on groundwater
Jin-Ho Yoon et al.
Environmental Research Letters, May 2018
Abstract:
The US state of Texas has experienced consecutive flooding events since spring 2015 with devastating consequences, yet these happened only a few years after the record drought of 2011. Identifying the effect of climate variability on regional water cycle extremes, such as the predicted occurrence of La Niña in winter 2017–2018 and its association with drought in Texas, remains a challenge. The present analyses use large-ensemble simulations to project the future of water cycle extremes in Texas and assess their connection with the changing El Niño–Southern Oscillation (ENSO) teleconnection under global warming. Large-ensemble simulations indicate that both intense drought and excessive precipitation are projected to increase towards the middle of the 21st century, associated with a strengthened effect from ENSO. Despite the precipitation increase projected for the southern Great Plains, groundwater storage is likely to decrease in the long run with diminishing groundwater recharge; this is due to the concurrent increases and strengthening in drought offsetting the effect of added rains. This projection provides implications to short-term climate anomaly in the face of the La Niña and to long-term water resources planning.