Boiling off
A changing climate of skepticism: The factors shaping climate change coverage in the US press
Hannah Schmid-Petri et al.
Public Understanding of Science, forthcoming
Abstract:
Skepticism toward climate change has a long tradition in the United States. We focus on mass media as the conveyors of the image of climate change and ask: Is climate change skepticism still a characteristic of US print media coverage? If so, to what degree and in what form? And which factors might pave the way for skeptics entering mass media debates? We conducted a quantitative content analysis of US print media during one year (1 June 2012 to 31 May 2013). Our results show that the debate has changed: fundamental forms of climate change skepticism (such as denial of anthropogenic causes) have been abandoned in the coverage, being replaced by more subtle forms (such as the goal to avoid binding regulations). We find no evidence for the norm of journalistic balance, nor do our data support the idea that it is the conservative press that boosts skepticism.
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Aaron McCright et al.
Topics in Cognitive Science, forthcoming
Abstract:
Prior research on the influence of various ways of framing anthropogenic climate change (ACC) do not account for the organized ACC denial in the U.S. media and popular culture, and thus may overestimate these frames' influence in the general public. We conducted an experiment to examine how Americans' ACC views are influenced by four promising frames for urging action on ACC (economic opportunity, national security, Christian stewardship, and public health) — when these frames appear with an ACC denial counter-frame. This is the first direct test of how exposure to an ACC denial message influences Americans' ACC views. Overall, these four positive frames have little to no effect on ACC beliefs. But exposure to an ACC denial counter-frame does significantly reduce respondents' belief in the reality of ACC, belief about the veracity of climate science, awareness of the consequences of ACC, and support for aggressively attempting to reduce our nation's GHG emissions in the near future. Furthermore, as expected by the Anti-Reflexivity Thesis, exposure to the ACC denial counter-frame has a disproportionate influence on the ACC views of conservatives (than on those of moderates and liberals), effectively activating conservatives' underlying propensity for anti-reflexivity.
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Mark Romeo Hoffarth & Gordon Hodson
Journal of Environmental Psychology, March 2016, Pages 40–49
Abstract:
Political polarization has been observed on climate change issues, with right-wing adherents more likely to deny climate change and oppose policies aimed at mitigation. Most theory and political discourse frames this divide as being driven by support for economy-driven environmental exploitation on the right. However, consistent with rhetoric characterizing environmentalists as “Communist watermelons” (i.e. green on the outside, red on the inside), we test an intergroup explanation for political polarization on climate change attitudes, with the perception that environmentalists are a threat to society also underlying right-wing climate change denial. In an American community sample (N = 384), environmentalist threat consistently, strongly, and uniquely accounted for the link between right-wing ideology and opposition to environmentalist policies and climate change denial, over and above views that the environment exists for economic exploitation and other relevant beliefs about the environment. Implications for encouraging climate change mitigation among right-wing adherents are discussed.
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From Cradle to Junkyard: Assessing the Life Cycle Greenhouse Gas Benefits of Electric Vehicles
James Archsmith, Alissa Kendall & David Rapson
Research in Transportation Economics, October 2015, Pages 72–90
Abstract:
U.S. programs subsidize electric vehicles (EVs) in part to reduce greenhouse gas (GHG) emissions. We model a suite of life cycle GHG emissions considerations to estimate the GHG abatement potential from switching from an internal combustion engine vehicle (ICE) to an EV in the continental U.S. The GHG intensity of EVs hinges on the electricity and ambient temperature when charged and operated. Both have high spatial and temporal heterogeneity, yet are typically modeled inadequately or overlooked entirely. We calculate marginal emissions, including renewables, for electricity by region and test forecasted grid composition to estimate future performance. Location and timing of charging are important GHG determinants, but temperature effects on EV performance can be equally important. On average, EVs slightly reduce GHGs relative to ICEs, but there are many regions where EVs provide a decisive benefit and others where EVs are significantly worse. The forecasted grid shifts from coal towards renewables, improving EV performance; the GHG benefit per EV in western states is roughly $425 today and $2400 in 2040.
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Long-term response of oceans to CO2 removal from the atmosphere
Sabine Mathesius et al.
Nature Climate Change, December 2015, Pages 1107–1113
Abstract:
Carbon dioxide removal (CDR) from the atmosphere has been proposed as a measure for mitigating global warming and ocean acidification. To assess the extent to which CDR might eliminate the long-term consequences of anthropogenic CO2 emissions in the marine environment, we simulate the effect of two massive CDR interventions with CO2 extraction rates of 5 GtC yr−1 and 25 GtC yr−1, respectively, while CO2 emissions follow the extended RCP8.5 pathway. We falsify two hypotheses: the first being that CDR can restore pre-industrial conditions in the ocean by reducing the atmospheric CO2 concentration back to its pre-industrial level, and the second being that high CO2 emissions rates (RCP8.5) followed by CDR have long-term oceanic consequences that are similar to those of low emissions rates (RCP2.6). Focusing on pH, temperature and dissolved oxygen, we find that even after several centuries of CDR deployment, past CO2 emissions would leave a substantial legacy in the marine environment.
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Rebecca Bromley-Trujillo, James Stoutenborough & Arnold Vedlitz
Climatic Change, December 2015, Pages 607-619
Abstract:
Public discourse on climate change often refers to possible bias among climate scientists as a rationale for limited climate policy action by the United States. Part of this discussion is the association of scientists with environmental interest groups and whether such affiliations facilitate the perception that climate scientists lack objectivity. While surveys suggest that some climate scientists disapprove of affiliations with interest groups, recent research indicates that climate scientists are quite likely to be involved with environmental organizations. This paper compares the affiliations of scientists and the general public to discern whether scientists are uniquely likely to affiliate with interest groups or they simply share characteristics common to the public who also affiliate with these organizations. Our findings suggest that climate scientists are no more likely to donate money, but are less likely to sign a petition or attend a demonstration, when controlling for other factors. These results strengthen our understanding of the affiliations between scientists and interest groups and hold implications for the accuracy of popular perceptions of climate scientists.
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John Wiener, Roger Pulwarty & David Ware
Weather and Climate Extremes, forthcoming
Abstract:
The drought of the 1950 s was among the most widespread, severe and sustained ever experienced in the United States. For several states, the severity of the 1950 s drought exceeded that of the 1930 s “Dust Bowl”. The 1950 s were characterized by low rainfall amounts and by excessively high temperatures. The climatological aspects of the drought subsided in most areas with the spring rains of 1957. A careful review of official reports over this period reveals limited acknowledgment of the drought of the 1950 s. The 1950 s drought was no secret, but it did not receive a great deal of news coverage; later droughts of lower severity and shorter duration, such as 1976-77, 1988, 2002-2004, 2011-2012 and the ongoing drought in California (2011-2015), garnered much greater national focus. In this paper, the question why such a major geophysical variation appears to have elicited little major national policy response, including the apparent lack of significant media concern is addressed. In framing the discussion this study assesses, the evolution of and impacts during the 1950 s to establish their national and regional policy contexts, technological improvements and financial changes prior to and during the event, and on and off-farm responses in terms of the socioeconomic impacts. An overview of key developments and concerns in agriculture since the early 20th Century that sets the context for the 1950 s, then move to the farm itself as a unit of analysis. This approach shows not only how the situation may have appeared to those outside the afflicted areas, but also how decisions were guided by agricultural economics affecting farmers at the time, and the strong influence of broader historical trends in which the 1950 s were embedded. The paper provides the relevant agricultural statistics and uncovers the political and public perceptions moving through the drought years. Overproduction was the fundamental, almost paradoxical problem facing American agriculture at the time. The paper concludes with a discussion of how the implications of this event and the attendant responses might provide guidance to future assessments of extremes such as severe drought in the context of a changing climate.
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Climate change as a migration driver from rural and urban Mexico
Raphael Nawrotzki et al.
Environmental Research Letters, November 2015
Abstract:
Studies investigating migration as a response to climate variability have largely focused on rural locations to the exclusion of urban areas. This lack of urban focus is unfortunate given the sheer numbers of urban residents and continuing high levels of urbanization. To begin filling this empirical gap, this study investigates climate change impacts on US-bound migration from rural and urban Mexico, 1986–1999. We employ geostatistical interpolation methods to construct two climate change indices, capturing warm and wet spell duration, based on daily temperature and precipitation readings for 214 weather stations across Mexico. In combination with detailed migration histories obtained from the Mexican Migration Project, we model the influence of climate change on household-level migration from 68 rural and 49 urban municipalities. Results from multilevel event-history models reveal that a temperature warming and excessive precipitation significantly increased international migration during the study period. However, climate change impacts on international migration is only observed for rural areas. Interactions reveal a causal pathway in which temperature (but not precipitation) influences migration patterns through employment in the agricultural sector. As such, climate-related international migration may decline with continued urbanization and the resulting reductions in direct dependence of households on rural agriculture.
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Adaptation to Climate Change: Evidence from US Agriculture
Marshall Burke & Kyle Emerick
American Economic Journal: Economic Policy, forthcoming
Abstract:
Understanding the potential impacts of climate change on economic outcomes requires knowing how agents might adapt to a changing climate. We exploit large variation in recent temperature and precipitation trends to identify adaptation to climate change in US agriculture, and use this information to generate new estimates of the potential impact of future climate change on agricultural outcomes. Longer-run adaptations appear to have mitigated less than half – and more likely none – of the large negative short-run impacts of extreme heat on productivity. Limited recent adaptation implies substantial losses under future climate change in the absence of countervailing investments.
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US major crops' uncertain climate change risks and greenhouse gas mitigation benefits
Ian Sue Wing et al.
Environmental Research Letters, November 2015
Abstract:
We estimate the costs of climate change to US agriculture, and associated potential benefits of abating greenhouse gas emissions. Five major crops' yield responses to climatic variation are modeled empirically, and the results combined with climate projections for a no-policy, high-warming future, as well as moderate and stringent mitigation scenarios. Unabated warming reduces yields of wheat and soybeans by 2050, and cotton by 2100, but moderate warming increases yields of all crops except wheat. Yield changes are monetized using the results of economic simulations within an integrated climate-economy modeling framework. Uncontrolled warming's economic effects on major crops are slightly positive — annual benefits <$4 B. These are amplified by emission reductions, but subject to diminishing returns — by 2100 reaching $17 B under moderate mitigation, but only $7 B with stringent mitigation. Costs and benefits are sensitive to irreducible uncertainty about the fertilization effects of elevated atmospheric carbon dioxide, without which unabated warming incurs net costs of up to $18 B, generating benefits to moderate (stringent) mitigation as large as $26 B ($20 B).
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Roberto Mera et al.
Climatic Change, December 2015, Pages 427-438
Abstract:
Probabilistic event attribution (PEA) is an important tool for assessing the contribution of climate change to extreme weather events. Here, PEA is applied to explore the climate attribution of recent extreme heat events in California’s Central Valley. Heat waves have become progressively more severe due to increasing relative humidity and nighttime temperatures, which increases the health risks of exposed communities, especially Latino farmworkers and other socioeconomically disadvantaged communities. Using a superensemble of simulations with the Hadley Centre Regional Model (HadRM3P), we find that (1) simulations of the hottest summer days during the 2000s were twice as likely to occur using observed levels of greenhouse gases than in a counterfactual world without major human activities, suggesting a strong relationship between heat extremes and the increase in human emissions of greenhouse gases, (2) detrimental impacts of heat on public health-relevant variables, such as the number of days above 40 °C, can be quantified and attributed to human activities using PEA, and (3) PEA can serve as a tool for addressing climate justice concerns of populations within developed nations who are disproportionately exposed to climate risks.
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The energy and emissions footprint of water supply for Southern California
A.J. Fang, Joshua Newell & Joshua Cousins
Environmental Research Letters, November 2015
Abstract:
Due to climate change and ongoing drought, California and much of the American West face critical water supply challenges. California's water supply infrastructure sprawls for thousands of miles, from the Colorado River to the Sacramento Delta. Bringing water to growing urban centers in Southern California is especially energy intensive, pushing local utilities to balance water security with factors such as the cost and carbon footprint of the various supply sources. To enhance water security, cities are expanding efforts to increase local water supply. But do these local sources have a smaller carbon footprint than imported sources? To answer this question and others related to the urban water–energy nexus, this study uses spatially explicit life cycle assessment to estimate the energy and emissions intensity of water supply for two utilities in Southern California: Los Angeles Department of Water and Power, which serves Los Angeles, and the Inland Empire Utility Agency, which serves the San Bernardino region. This study differs from previous research in two significant ways: (1) emissions factors are based not on regional averages but on the specific electric utility and generation sources supplying energy throughout transport, treatment, and distribution phases of the water supply chain; (2) upstream (non-combustion) emissions associated with the energy sources are included. This approach reveals that in case of water supply to Los Angeles, local recycled water has a higher carbon footprint than water imported from the Colorado River. In addition, by excluding upstream emissions, the carbon footprint of water supply is potentially underestimated by up to 30%. These results have wide-ranging implications for how carbon footprints are traditionally calculated at local and regional levels. Reducing the emissions intensity of local water supply hinges on transitioning the energy used to treat and distribute water away from fossil fuel, sources such as coal.
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Extratropical Cyclones in Idealized Simulations of Changed Climates
Stephan Pfahl, Paul O’Gorman & Martin Singh
Journal of Climate, December 2015, Pages 9373–9392
Abstract:
Cyclones are a key element of extratropical weather and frequently lead to extreme events like wind storms and heavy precipitation. Understanding potential changes of cyclone frequency and intensity is thus essential for a proper assessment of climate change impacts. Here the behavior of extratropical cyclones under strongly varying climate conditions is investigated using idealized climate model simulations in an aquaplanet setup. A cyclone tracking algorithm is applied to assess various statistics of cyclone properties such as intensity, size, lifetime, displacement velocity, and deepening rates. In addition, a composite analysis of intense cyclones is performed. In general, the structure of extratropical cyclones in the idealized simulations is very robust, and changes in major cyclone characteristics are relatively small. Median cyclone intensity, measured in terms of minimum sea level pressure and lower-tropospheric relative vorticity, has a maximum in simulations with global mean temperature slightly warmer than present-day Earth, broadly consistent with the behavior of the eddy kinetic energy analyzed in previous studies. Maximum deepening rates along cyclone tracks behave similarly and are in agreement with linear quasigeostrophic growth rates if the effect of latent heat release on the stratification is taken into account. In contrast to moderate cyclones, the relative vorticity of intense cyclones continues to increase with warming to substantially higher temperatures, and this is associated with enhanced lower-tropospheric potential vorticity anomalies likely caused by increased diabatic heating. Moist processes may, therefore, lead to the further strengthening of intense cyclones in warmer climates even if cyclones weaken on average.
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Top ten European heatwaves since 1950 and their occurrence in the coming decades
Simone Russo, Jana Sillmann & Erich Fischer
Environmental Research Letters, December 2015
Abstract:
The Russian heatwave in 2010 killed tens of thousands of people, and was by far the worst event in Europe since at least 1950, according to recent studies and a novel universal heatwave index capturing both the duration and magnitude of heatwaves. Here, by taking an improved version of this index, namely the heat wave magnitude index daily, we rank the top ten European heatwaves that occurred in the period 1950–2014, and show the spatial distribution of the magnitude of the most recent heatwave in summer 2015. We demonstrate that all these events had a strong impact reported in historical newspapers. We further reveal that the 1972 heatwave in Finland had a comparable spatial extent and magnitude as the European heatwave of 2003, considered the second strongest heatwave of the observational era. In the next two decades (2021–2040), regional climate projections suggest that Europe experiences an enhanced probability for heatwaves comparable to or greater than the magnitude, extent and duration of the Russian heatwave in 2010. We demonstrate that the probability of experiencing a major European heatwave in the coming decades is higher in RCP8.5 than RCP4.5 even though global mean temperature projections do not differ substantially. This calls for a proactive vulnerability assessment in Europe in support of formulating heatwave adaptation strategies to reduce the adverse impacts of heatwaves.
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Ocean acidification and global warming impair shark hunting behaviour and growth
Jennifer Pistevos et al.
Scientific Reports, November 2015
Abstract:
Alterations in predation pressure can have large effects on trophically-structured systems. Modification of predator behaviour via ocean warming has been assessed by laboratory experimentation and metabolic theory. However, the influence of ocean acidification with ocean warming remains largely unexplored for mesopredators, including experimental assessments that incorporate key components of the assemblages in which animals naturally live. We employ a combination of long-term laboratory and mesocosm experiments containing natural prey and habitat to assess how warming and acidification affect the development, growth, and hunting behaviour in sharks. Although embryonic development was faster due to temperature, elevated temperature and CO2 had detrimental effects on sharks by not only increasing energetic demands, but also by decreasing metabolic efficiency and reducing their ability to locate food through olfaction. The combination of these effects led to considerable reductions in growth rates of sharks held in natural mesocosms with elevated CO2, either alone or in combination with higher temperature. Our results suggest a more complex reality for predators, where ocean acidification reduces their ability to effectively hunt and exert strong top-down control over food webs.
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Potential sea-level rise from Antarctic ice-sheet instability constrained by observations
Catherine Ritz et al.
Nature, 3 December 2015, Pages 115–118
Abstract:
Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B, although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.