Cool It
Leah Stokes
American Journal of Political Science, forthcoming
Abstract:
Retrospective voting studies typically examine policies where the public has common interests. By contrast, climate policy has broad public support but concentrated opposition in communities where costs are imposed. This spatial distribution of weak supporters and strong local opponents mirrors opposition to other policies with diffuse public benefits and concentrated local costs. I use a natural experiment to investigate whether citizens living in proximity to wind energy projects retrospectively punished an incumbent government because of its climate policy. Using both fixed effects and instrumental variable estimators, I identify electoral losses for the incumbent party ranging from 4 to 10%, with the effect persisting 3 km from wind turbines. There is also evidence that voters are informed, only punishing the government responsible for the policy. I conclude that the spatial distribution of citizens' policy preferences can affect democratic accountability through ‘spatially distorted signalling’, which can exacerbate political barriers to addressing climate change.
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More than Markets: A Comparative Study of Nine Conservative Parties on Climate Change
Sondre Båtstrand
Politics & Policy, August 2015, Pages 538–561
Abstract:
Cross-national comparisons of proposed policies of individual parties are an underdeveloped part of the literature on environmental politics in general and climate politics in particular. Although conservative parties are portrayed as skeptical toward adopting climate measures or even supposed to ignore climate change, this study of nine conservative electoral manifestoes nevertheless finds that most of them support climate measures, even in the form of state interventions in the market economy. Market measures are not as dominating as could be expected, but a clear finding is that available fossil reserves seem to have an influence on conservative climate politics. The U.S. Republican Party is an anomaly in denying anthropogenic climate change. Conservative parties as such are not in opposition to climate policies, but the pro-business position is evident in that conservative parties do not challenge coal or petroleum in countries with large reserves of these resources.
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Salience of Carbon Taxes in the Gasoline Market
Nicholas Rivers & Brandon Schaufele
Journal of Environmental Economics and Management, November 2015, Pages 23–36
Abstract:
We demonstrate that the carbon tax imposed by the Canadian province of British Columbia caused a decline in short-run gasoline demand that is significantly greater than would be expected from an equivalent increase in the market price of gasoline. That the carbon tax is more salient, or yields a larger change in demand than equivalent market price movements, is robust to a range of specifications. As a result of the large consumer response to the tax, we calculate that during its first four years, the tax reduced carbon dioxide emissions from gasoline consumption by 2.4 million tonnes.
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Storms and Jobs: The Effect of Hurricanes on Individuals' Employment and Earnings over the Long Term
Jeffrey Groen, Mark Kutzbach & Anne Elise Polivka
U.S. Census Bureau Working Paper, August 2015
Abstract:
We study the responsiveness of individuals’ employment and earnings to the damages and disruption caused by Hurricanes Katrina and Rita, which struck the U.S. Gulf Coast in 2005. Our analysis is based on individual-level survey and administrative data that tracks workers over time, both in the immediate aftermath of the storm and over a seven-year period. For individuals who were employed at the time of the storm, we estimate models that compare the evolution of earnings for individuals who resided in storm-affected areas and individuals who resided in a set of control counties with pre-storm characteristics similar to those of the storm-affected areas prior to the storm. We find that, on average, the storms reduced the earnings of affected individuals during the first year after the storm. These losses reflect various aspects of the short-run disruption caused by the hurricanes, including job separations, migration to other areas, and business contractions. Starting in the third year after the storms, however, we estimate that the storms increased the quarterly earnings of affected individuals. We provide evidence that the long-term earnings gains experienced by affected individuals were the result of differences in wage growth between the affected areas and the control areas, due to reduced labor supply and increased labor demand, especially in sectors related to rebuilding. Despite short-term earnings losses due to an increased rate of non-employment, we find a net increase in average quarterly earnings among affected individuals over the entire post-storm period. However, subgroups with large and persistent earnings losses after the storms had a net decrease in average quarterly earnings over the seven-year period due to the storms.
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Joint projections of US East Coast sea level and storm surge
Christopher Little et al.
Nature Climate Change, forthcoming
Abstract:
Future coastal flood risk will be strongly influenced by sea-level rise (SLR) and changes in the frequency and intensity of tropical cyclones. These two factors are generally considered independently. Here, we assess twenty-first century changes in the coastal hazard for the US East Coast using a flood index (FI) that accounts for changes in flood duration and magnitude driven by SLR and changes in power dissipation index (PDI, an integrated measure of tropical cyclone intensity, frequency and duration). Sea-level rise and PDI are derived from representative concentration pathway (RCP) simulations of 15 atmosphere–ocean general circulation models (AOGCMs). By 2080–2099, projected changes in the FI relative to 1986–2005 are substantial and positively skewed: a 10th–90th percentile range 4–75 times higher for RCP 2.6 and 35–350 times higher for RCP 8.5. High-end FI projections are driven by three AOGCMs that project the largest increases in SLR, PDI and upper ocean temperatures. Changes in PDI are particularly influential if their intra-model correlation with SLR is included, increasing the RCP 8.5 90th percentile FI by a further 25%. Sea-level rise from other, possibly correlated, climate processes (for example, ice sheet and glacier mass changes) will further increase coastal flood risk and should be accounted for in comprehensive assessments.
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Bala Rajaratnam et al.
Climatic Change, forthcoming
Abstract:
The reported “hiatus” in the warming of the global climate system during this century has been the subject of intense scientific and public debate, with implications ranging from scientific understanding of the global climate sensitivity to the rate in which greenhouse gas emissions would need to be curbed in order to meet the United Nations global warming target. A number of scientific hypotheses have been put forward to explain the hiatus, including both physical climate processes and data artifacts. However, despite the intense focus on the hiatus in both the scientific and public arenas, rigorous statistical assessment of the uniqueness of the recent temperature time-series within the context of the long-term record has been limited. We apply a rigorous, comprehensive statistical analysis of global temperature data that goes beyond simple linear models to account for temporal dependence and selection effects. We use this framework to test whether the recent period has demonstrated i) a hiatus in the trend in global temperatures, ii) a temperature trend that is statistically distinct from trends prior to the hiatus period, iii) a “stalling” of the global mean temperature, and iv) a change in the distribution of the year-to-year temperature increases. We find compelling evidence that recent claims of a “hiatus” in global warming lack sound scientific basis. Our analysis reveals that there is no hiatus in the increase in the global mean temperature, no statistically significant difference in trends, no stalling of the global mean temperature, and no change in year-to-year temperature increases.
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Substantial increase in concurrent droughts and heatwaves in the United States
Omid Mazdiyasni & Amir AghaKouchak
Proceedings of the National Academy of Sciences, 15 September 2015, Pages 11484–11489
Abstract:
A combination of climate events (e.g., low precipitation and high temperatures) may cause a significant impact on the ecosystem and society, although individual events involved may not be severe extremes themselves. Analyzing historical changes in concurrent climate extremes is critical to preparing for and mitigating the negative effects of climatic change and variability. This study focuses on the changes in concurrences of heatwaves and meteorological droughts from 1960 to 2010. Despite an apparent hiatus in rising temperature and no significant trend in droughts, we show a substantial increase in concurrent droughts and heatwaves across most parts of the United States, and a statistically significant shift in the distribution of concurrent extremes. Although commonly used trend analysis methods do not show any trend in concurrent droughts and heatwaves, a unique statistical approach discussed in this study exhibits a statistically significant change in the distribution of the data.
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Causes of the 2011–14 California Drought
Richard Seager et al.
Journal of Climate, September 2015, Pages 6997–7024
Abstract:
The causes of the California drought during November–April winters of 2011/12–2013/14 are analyzed using observations and ensemble simulations with seven atmosphere models forced by observed SSTs. Historically, dry California winters are most commonly associated with a ridge off the west coast but no obvious SST forcing. Wet winters are most commonly associated with a trough off the west coast and an El Niño event. These attributes of dry and wet winters are captured by many of the seven models. According to the models, SST forcing can explain up to a third of California winter precipitation variance. SST forcing was key to sustaining a high pressure ridge over the west coast and suppressing precipitation during the three winters. In 2011/12 this was a response to a La Niña event, whereas in 2012/13 and 2013/14 it appears related to a warm west–cool east tropical Pacific SST pattern. All models contain a mode of variability linking such tropical Pacific SST anomalies to a wave train with a ridge off the North American west coast. This mode explains less variance than ENSO and Pacific decadal variability, and its importance in 2012/13 and 2013/14 was unusual. The models from phase 5 of CMIP (CMIP5) project rising greenhouse gases to cause changes in California all-winter precipitation that are very small compared to recent drought anomalies. However, a long-term warming trend likely contributed to surface moisture deficits during the drought. As such, the precipitation deficit during the drought was dominated by natural variability, a conclusion framed by discussion of differences between observed and modeled tropical SST trends.
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Climate constraints on the carbon intensity of economic growth
Julie Rozenberg et al.
Environmental Research Letters, September 2015
Abstract:
Development and climate goals together constrain the carbon intensity of production. Using a simple and transparent model that represents committed CO2 emissions (future emissions expected to come from existing capital), we explore the carbon intensity of production related to new capital required for different temperature targets across several thousand scenarios. Future pathways consistent with the 2 °C target which allow for continued gross domestic product growth require early action to reduce carbon intensity of new production, and either (i) a short lifetime of energy and industry capital (e.g. early retrofit of coal power plants), or (ii) large negative emissions after 2050 (i.e. rapid development and dissemination of carbon capture and sequestration). To achieve the 2 °C target, half of the scenarios indicate a carbon intensity of new production between 33 and 73 g CO2/$—much lower than the global average today, at 360 g CO2/$. The average lifespan of energy capital (especially power plants), and industry capital, are critical because they commit emissions far into the future and reduce the budget for new capital emissions. Each year of lifetime added to existing, carbon intensive capital, decreases the carbon intensity of new production required to meet a 2 °C carbon budget by 1.0–1.5 g CO2/$, and each year of delaying the start of mitigation decreases the required CO2 intensity of new production by 20–50 g CO2/$. Constraints on the carbon intensity of new production under a 3 °C target are considerably relaxed relative to the 2 °C target, but remain daunting in comparison to the carbon intensity of the global economy today.
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Autonomous taxis could greatly reduce greenhouse-gas emissions of US light-duty vehicles
Jeffery Greenblatt & Samveg Saxena
Nature Climate Change, September 2015, Pages 860–863
Abstract:
Autonomous vehicles (AVs) are conveyances to move passengers or freight without human intervention. AVs are potentially disruptive both technologically and socially, with claimed benefits including increased safety, road utilization, driver productivity and energy savings. Here we estimate 2014 and 2030 greenhouse-gas (GHG) emissions and costs of autonomous taxis (ATs), a class of fully autonomous shared AVs likely to gain rapid early market share, through three synergistic effects: (1) future decreases in electricity GHG emissions intensity, (2) smaller vehicle sizes resulting from trip-specific AT deployment, and (3) higher annual vehicle-miles travelled (VMT), increasing high-efficiency (especially battery-electric) vehicle cost-effectiveness. Combined, these factors could result in decreased US per-mile GHG emissions in 2030 per AT deployed of 87–94% below current conventionally driven vehicles (CDVs), and 63–82% below projected 2030 hybrid vehicles, without including other energy-saving benefits of AVs. With these substantial GHG savings, ATs could enable GHG reductions even if total VMT, average speed and vehicle size increased substantially. Oil consumption would also be reduced by nearly 100%.
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Extinction Events Can Accelerate Evolution
Joel Lehman & Risto Miikkulainen
PLoS ONE, August 2015
Abstract:
Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific in the long term.
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Landing on empty: Estimating the benefits from reducing fuel uplift in US Civil Aviation
Megan Ryerson et al.
Environmental Research Letters, September 2015
Abstract:
Airlines and Air Navigation Service Providers are united in their goal to reduce fuel consumption. While changes to flight operations and technology investments are the focus of a number of studies, our study is among the first to investigate an untapped source of aviation fuel consumption: excess contingency fuel loading. Given the downside risk of fuel exhaustion of diverting to an alternate airport, airline dispatchers may load excess fuel onto an aircraft. Such conservatism comes at a cost of consuming excess fuel, as fuel consumed is a function of, among other factors, aircraft weight. The aim of this paper is to quantify, on a per-flight basis, the fuel burned due to carrying fuel beyond what is needed for foreseeable contingencies, and thereby motivate research, federal guidance, and investments that allow airline dispatchers to reduce fuel uplift while maintaining near zero risks of fuel exhaustion. We merge large publicly available aviation and weather databases with a detailed dataset from a major US airline. Upon estimating factors that capture the quantity fuel consumed due to carrying a pound of weight for a range of aircraft types, we calculate the cost and greenhouse gas emissions from carrying unused fuel on arrival and additional contingency fuel above a conservative buffer for foreseeable contingencies. We establish that the major US carrier does indeed load fuel conservatively. We find that 4.48% of the fuel consumed by an average flight is due to carrying unused fuel and 1.04% of the fuel consumed by an average flight is due to carrying additional contingency fuel above a reasonable buffer. We find that simple changes in flight dispatching that maintain a statistically minimal risk of fuel exhaustion could result in yearly savings of 338 million lbs of CO2, the equivalent to the fuel consumed from 4760 flights on midsized commercial aircraft. Moreover, policy changes regarding maximum fuel loads or investments that reduce uncertainty or increase the ability to plan flights under uncertainty could yield far greater benefits.
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Detection and Analysis of an Amplified Warming of the Sahara Desert
Kerry Cook & Edward Vizy
Journal of Climate, August 2015, Pages 6560–6580
Abstract:
Evaluation of three reanalyses (ERA-Interim, NCEP-2, and MERRA) and two observational datasets [CRU and Global Historical Climatology Network (GHCN)] for 1979–2012 demonstrates that the surface temperature of the Sahara Desert has increased at a rate that is 2–4 times greater than that of the tropical-mean temperature over the 34-yr time period. While the response to enhanced greenhouse gas forcing over most of the globe involves the full depth of the atmosphere, with increases in longwave back radiation increasing latent heat fluxes, the dryness of the Sahara surface precludes this response. Changes in the surface heat balance over the Sahara during the analysis period are primarily in the upward and downward longwave fluxes. As a result, the warming is concentrated near the surface, and a desert amplification of the warming occurs. The desert amplification is analogous to the polar amplification of the global warming signal, which is concentrated at the surface, in part, because of the vertical stability of the Arctic atmosphere. Accompanying the amplified surface warming of the Sahara is a strengthening of both the summertime heat low and the African easterly jet and a weakening of the wintertime anticyclone and the low-level Harmattan winds. Potential implications of the desert amplification include decreases in mineral dust aerosols globally, decreases in wintertime cold air surge activity, and increases in Sahel rainfall.
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Sander van der Linden
Personality and Individual Differences, December 2015, Pages 171–173
Abstract:
Although public endorsement of conspiracy theories is growing, the potentially negative societal consequences of widespread conspiracy ideation remain unclear. While past studies have mainly examined the personality correlates of conspiracy ideation, this study examines the conspiracy-effect; the extent to which exposure to an actual conspiracy theory influences pro-social and environmental decision-making. Participants (N = 316) were randomly assigned to one of three conditions; (a) a brief conspiracy video about global warming, (b) an inspirational pro-climate video or (c) a control group. Results indicate that those participants who were exposed to the conspiracy video were significantly less likely to think that there is widespread scientific agreement on human-caused climate change, less likely to sign a petition to help reduce global warming and less likely to donate or volunteer for a charity in the next six months. These results strongly point to the socio-cognitive potency of conspiracies and highlight that exposure to popular conspiracy theories can have negative and undesirable societal consequences.
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Projected impacts of climate change on wind energy density in the United States
Dana Johnson & Robert Erhardt
Renewable Energy, January 2016, Pages 66–73
Abstract:
Wind-generated electricity is a growing renewable energy resource. Because wind results from the uneven heating (and resulting pressure gradients) of the Earth, future wind resources may be affected by anticipated climate change. Many studies have used global and regional climate models to predict trends in the future wind resource over the continental United States. While some of these studies identified regions that are expected to gain wind energy, their results often come with a high degree of uncertainty, and lack of agreement across different climate models. In this paper we focus on wind energy density as a measure of the available wind resource over the continental United States. We estimate the change in wind energy density from the period 1968–2000 to the period 2038–2070 by using output from four regional climate models from the North American Regional Climate Change Assessment Program (NARCCAP). We find strong agreement across all 4 models that the wind energy resource is expected to increase in parts of Kansas, Oklahoma, and northern Texas – a region already in possession of both large scale generating capacity and political support for wind energy.
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The effectiveness of net negative carbon dioxide emissions in reversing anthropogenic climate change
Katarzyna Tokarska & Kirsten Zickfeld
Environmental Research Letters, September 2015
Abstract:
Artificial removal of CO2 from the atmosphere (also referred to as negative emissions) has been proposed as a means to restore the climate system to a desirable state, should the impacts of climate change become 'dangerous'. Here we explore whether negative emissions are indeed effective in reversing climate change on human timescales, given the potentially counteracting effect of natural carbon sinks and the inertia of the climate system. We designed a range of CO2 emission scenarios, which follow a gradual transition to a zero-carbon energy system and entail implementation of various amounts of net-negative emissions at technologically plausible rates. These scenarios are used to force an Earth System Model of intermediate complexity. Results suggest that while it is possible to revert to a desired level of warming (e.g. 2 °C above pre-industrial) after different levels of overshoot, thermosteric sea level rise is not reversible for at least several centuries, even under assumption of large amounts of negative CO2 emissions. During the net-negative emission phase, artificial CO2 removal is opposed by CO2 outgassing from natural carbon sinks, with the efficiency of CO2 removal — here defined as the drop in atmospheric CO2 per unit negative emission — decreasing with the total amount of negative emissions.
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Robust global ocean cooling trend for the pre-industrial Common Era
Helen McGregor et al.
Nature Geoscience, September 2015, Pages 671–677
Abstract:
The oceans mediate the response of global climate to natural and anthropogenic forcings. Yet for the past 2,000 years — a key interval for understanding the present and future climate response to these forcings — global sea surface temperature changes and the underlying driving mechanisms are poorly constrained. Here we present a global synthesis of sea surface temperatures for the Common Era (CE) derived from 57 individual marine reconstructions that meet strict quality control criteria. We observe a cooling trend from 1 to 1800 CE that is robust against explicit tests for potential biases in the reconstructions. Between 801 and 1800 CE, the surface cooling trend is qualitatively consistent with an independent synthesis of terrestrial temperature reconstructions, and with a sea surface temperature composite derived from an ensemble of climate model simulations using best estimates of past external radiative forcings. Climate simulations using single and cumulative forcings suggest that the ocean surface cooling trend from 801 to 1800 CE is not primarily a response to orbital forcing but arises from a high frequency of explosive volcanism. Our results show that repeated clusters of volcanic eruptions can induce a net negative radiative forcing that results in a centennial and global scale cooling trend via a decline in mixed-layer oceanic heat content.