Meltdown
Global rules mask the mitigation challenge facing developing countries
Xuemei Jiang, Glen Peters & Christopher Green
Earth's Future, forthcoming
Abstract:
Focusing on global mitigation pathways masks key aspects of technical, political, and social feasibility, which play out at the country level. We illustrate the dilemma between a “carbon law” (halving emissions every decade) at the global level and the nationally determined contributions (NDCs) submitted at the country level. Our results suggest that even if the US, EU, China and India could strengthen their NDCs by 2050, the rest of the world (RoW) is required to immediately change from their current course to a very rapid decrease in emissions reaching almost zero emissions by 2030, to achieve the Paris 2015 goal. The greatest mitigation challenges lie in the developing world. Real progress toward the Paris Agreement goal awaits an effective commitment by leading countries to undertake breakthrough research and development of low‐, zero‐ or even negative‐carbon‐emissions energy technologies that can be deployed at scale in the developing world.
Is Temperature Exogenous? The Impact of Civil Conflict on the Instrumental Climate Record in Sub‐Saharan Africa
Kenneth Schultz & Justin Mankin
American Journal of Political Science, forthcoming
Abstract:
Research into the effects of climate on political and economic outcomes assumes that short‐term variation in weather is exogenous to the phenomena being studied. However, weather data are derived from stations operated by national governments, whose political capacity and stability affect the quality and continuity of coverage. We show that civil conflict risk in sub‐Saharan Africa is negatively correlated with the number and density of weather stations contributing to a country's temperature record. This effect is both cross‐sectional — countries with higher average conflict risk tend to have poorer coverage — and cross‐temporal — civil conflict leads to loss of weather stations. Poor coverage induces a small downward bias in one widely used temperature data set, due to its interpolation method, and increases measurement error, potentially attenuating estimates of the temperature–conflict relationship. Combining multiple observational data sets to reduce measurement error almost doubles the estimated effect of temperature anomalies on civil conflict risk.
Hot temperatures and even hotter tempers: Sociological mediators in the relationship between global climate change and homicide
Christopher Barlett et al.
Psychology of Violence, forthcoming
Method: Data from the World Bank were accumulated between 1961 and 2015 on the aforementioned variables. Ambient temperature (1961–1989), number of extreme weather events (1990–2009), access to clean drinking water (2010), food production (2010), and homicide rates (2011–2015) were analyzed.
Results: Correlational analyses showed that ambient temperature across the world positively predicted the number of extreme weather events and homicide rates but negatively correlated with access to clean drinking water. Path modeling showed support for our primary thesis that ambient temperatures positively predicted extreme weather events, which, in turn, negatively predicted access to clean drinking water to positively predict homicide rates. Mediation tests confirmed these relationships.
Climate Sensitivity and Predictable Returns
Alok Kumar, Wei Xin & Chendi Zhang
University of Miami Working Paper, February 2019
Abstract:
The paper finds that firms' exposure to temperature changes predicts stock returns. We use the sensitivity of stock returns to abnormal temperature changes to measure firm-level climate sensitivity. Stocks with higher climate sensitivity forecast lower stock returns. A trading strategy that exploits the return predictability generates risk-adjusted returns of 3.6% per year from 1931 to 2017. Further, climate sensitivity also predicts lower firm profits. Our results are robust to controlling for macroeconomics conditions and asymmetric return sensitivity to temperature changes. Overall, these findings are consistent with stock markets underreacting to firms' climate sensitivity.
The Macroeconomic Effects of 2017 Through 2025 Federal Fuel Economy and Greenhouse Gas Emissions Standards
Sanya Carley et al.
Journal of Policy Analysis and Management, forthcoming
Abstract:
In the absence of a national carbon price, the federal Corporate Average Fuel Economy standards and the related greenhouse gas emissions (GHG) standards are the primary mechanisms through which the U.S. reduces transportation GHG emissions. In 2012, these standards were set to rise for light‐duty vehicles between 2017 and 2025, eventually achieving a target of 54.5 miles per gallon in 2025. Since 2012, conditions have changed: forecasts of future gasoline prices have dropped dramatically, consumers have demanded larger vehicles, and the cost of compliance appears to be larger than previously thought. In this article, we analyze the possible macroeconomic effects of the standards with both 2012 inputs and updated inputs to reflect these new market developments. The results reveal that the short‐term effects of the federal standards will be negative, but the long‐term effects will be positive, using both 2012 and updated inputs. The transition from annual negative employment impacts to positive impacts occurs between 2023 and 2026, depending on which set of assumptions are used. Possible revisions to the standards that freeze them at 2020 levels or decrease their stringency reduce short‐term negative impacts but also reduce long‐term positive impacts. We conclude with a discussion of policy implications as they relate to the current energy and climate policy conditions.
The Kyoto protocol: Empirical evidence of a hidden success
Nada Maamoun
Journal of Environmental Economics and Management, forthcoming
Abstract:
How effective was the Kyoto protocol? International Environmental Agreements (IEA) have been on the rise over the past four decades; however, thus far their effectiveness is controversial. In view of the conflicting results found in the related literature, this paper addresses its effectiveness by utilizing for the first time the generalized synthetic control method (GSCM) to compare the emissions of the industrialized countries with a “No- Kyoto” counterfactual scenario that represents the expected emissions in the absence of the protocol. This method facilitates a robust comparison between treated and control countries as done by Almer and Winkler (2017) and account for the multiple treated units as done by Grunewald and Martinez-Zarzoso (2016), so as to capture the collective nature of the protocol. Results show that the protocol was successful in reducing the emissions of the ratifying countries approximately by 7% below the emissions expected under a “No-Kyoto” scenario, confirming the importance of accounting for the collective nature of the agreement.
Climate Change and Occupational Health: Are There Limits to Our Ability to Adapt?
Marcus Dillender
Journal of Human Resources, forthcoming
Abstract:
This study considers the relationship between temperature and occupational health. The results indicate that both high and low temperatures increase injury rates and that high temperatures have more severe adverse effects in warmer climates, which suggests that avoiding the adverse effects of high temperatures may be easier for workers when hot days are rarer. While research on the effect of temperature on mortality finds substantial capacity for adaptation with current technology, the results presented here suggest that outdoor workers face challenges in adapting to high temperatures.
Halving warming with idealized solar geoengineering moderates key climate hazards
Peter Irvine et al.
Nature Climate Change, April 2019, Pages 295–299
Abstract:
Solar geoengineering (SG) has the potential to restore average surface temperatures by increasing planetary albedo, but this could reduce precipitation. Thus, although SG might reduce globally aggregated risks, it may increase climate risks for some regions. Here, using the high-resolution forecast-oriented low ocean resolution (HiFLOR) model — which resolves tropical cyclones and has an improved representation of present-day precipitation extremes — alongside 12 models from the Geoengineering Model Intercomparison Project (GeoMIP), we analyse the fraction of locations that see their local climate change exacerbated or moderated by SG. Rather than restoring temperatures, we assume that SG is applied to halve the warming produced by doubling CO2 (half-SG). In HiFLOR, half-SG offsets most of the CO2-induced increase of simulated tropical cyclone intensity. Moreover, neither temperature, water availability, extreme temperature nor extreme precipitation are exacerbated under half-SG when averaged over any Intergovernmental Panel on Climate Change (IPCC) Special Report on Extremes (SREX) region. Indeed, for both extreme precipitation and water availability, less than 0.4% of the ice-free land surface sees exacerbation. Thus, while concerns about the inequality of solar geoengineering impacts are appropriate, the quantitative extent of inequality may be overstated.
Effects of fossil fuel and total anthropogenic emission removal on public health and climate
Jos Lelieveld et al.
Proceedings of the National Academy of Sciences, 9 April 2019, Pages 7192-7197
Abstract:
Anthropogenic greenhouse gases and aerosols are associated with climate change and human health risks. We used a global model to estimate the climate and public health outcomes attributable to fossil fuel use, indicating the potential benefits of a phaseout. We show that it can avoid an excess mortality rate of 3.61 (2.96–4.21) million per year from outdoor air pollution worldwide. This could be up to 5.55 (4.52–6.52) million per year by additionally controlling nonfossil anthropogenic sources. Globally, fossil-fuel-related emissions account for about 65% of the excess mortality, and 70% of the climate cooling by anthropogenic aerosols. The chemical influence of air pollution on aeolian dust contributes to the aerosol cooling. Because aerosols affect the hydrologic cycle, removing the anthropogenic emissions in the model increases rainfall by 10–70% over densely populated regions in India and 10–30% over northern China, and by 10–40% over Central America, West Africa, and the drought-prone Sahel, thus contributing to water and food security. Since aerosols mask the anthropogenic rise in global temperature, removing fossil-fuel-generated particles liberates 0.51(±0.03) °C and all pollution particles 0.73(±0.03) °C warming, reaching around 2 °C over North America and Northeast Asia. The steep temperature increase from removing aerosols can be moderated to about 0.36(±0.06) °C globally by the simultaneous reduction of tropospheric ozone and methane. We conclude that a rapid phaseout of fossil-fuel-related emissions and major reductions of other anthropogenic sources are needed to save millions of lives, restore aerosol-perturbed rainfall patterns, and limit global warming to 2 °C.
Public support for carbon dioxide removal strategies: The role of tampering with nature perceptions
Kimberly Wolske et al.
Climatic Change, March 2019, Pages 345–361
Abstract:
Carbon dioxide removal (CDR) describes a suite of controversial approaches to mitigating climate change that involve removing existing carbon dioxide from the atmosphere. Through an online survey experiment with US adults (N = 980), we examine three factors that may shape public support for different types of CDR strategies: (1) perceptions that CDR tampers with nature, (2) individual-level variation in the degree to which people are uncomfortable with activities that tamper with nature, and (3) information about the risks and benefits associated with each CDR strategy. Using a moderated mediation analysis, we find that support for different CDR strategies is, in part, a function of how much each strategy is perceived to tamper with nature. Support for bioenergy with carbon capture and storage (BECCS) and direct air capture (DAC) was lower than support for afforestation and reforestation (AR), as BECCS and DAC were perceived to tamper with nature more. These effects were particularly strong among individuals generally opposed to the idea of humans interfering with natural processes. Moreover, we find evidence that describing the risks and benefits of each CDR strategy dampens support; for AR and BECCS, this effect was again mediated through perceptions of tampering, while for DAC, the effect of describing these tradeoffs appeared to operate independently of perceived tampering. We conclude that policymakers and science communicators need to be mindful of how CDR strategies are described to the public, as perceptions of tampering with nature may be an important driver of their acceptance.
Comparative net energy analysis of renewable electricity and carbon capture and storage
Sgouris Sgouridis et al.
Nature Energy, forthcoming
Abstract:
Carbon capture and storage (CCS) for fossil-fuel power plants is perceived as a critical technology for climate mitigation. Nevertheless, limited installed capacity to date raises concerns about the ability of CCS to scale sufficiently. Conversely, scalable renewable electricity installations — solar and wind — are already deployed at scale and have demonstrated a rapid expansion potential. Here we show that power-sector CO2 emission reductions accomplished by investing in renewable technologies generally provide a better energetic return than CCS. We estimate the electrical energy return on energy invested ratio of CCS projects, accounting for their operational and infrastructural energy penalties, to range between 6.6:1 and 21.3:1 for 90% capture ratio and 85% capacity factor. These values compare unfavourably with dispatchable scalable renewable electricity with storage, which ranges from 9:1 to 30+:1 under realistic configurations. Therefore, renewables plus storage provide a more energetically effective approach to climate mitigation than constructing CCS fossil-fuel power stations.
The Impact of Global Warming on Rural-Urban Migrations: Evidence from Global Big Data
Giovanni Peri & Akira Sasahara
NBER Working Paper, April 2019
Abstract:
This paper examines the impact of temperature changes on rural-urban migration using a 56km×56km grid cell level dataset covering the whole world at 10-year frequency during the period 1970-2000. We find that rising temperatures reduce rural-urban migration in poor countries and increase such migration in middle-income countries. These asymmetric migration responses are consistent with a simple model where rural-urban earnings differentials and liquidity constraints interact to determine rural-to-urban migration flows. We also confirm these temperature effects using country-level observations constructed by aggregating the grid cell level data. We project that expected warming in the next century will encourage further urbanization in middle-income countries such as Argentina, but it will slow down urban transition in poor countries like Malawi and Niger.
Robust abatement pathways to tolerable climate futures require immediate global action
J.R. Lamontagne et al.
Nature Climate Change, April 2019, Pages 290–294
Abstract:
Disentangling the relative importance of climate change abatement policies from the human–Earth system (HES) uncertainties that determine their performance is challenging because the two are inexorably linked, and the nature of this linkage is dynamic, interactive and metric specific. Here, we demonstrate an approach to quantify the individual and joint roles that diverse HES uncertainties and our choices in abatement policy play in determining future climate and economic conditions, as simulated by an improved version of the Dynamic Integrated model of Climate and the Economy. Despite wide-ranging HES uncertainties, the growth rate of global abatement (a societal choice) is the primary driver of long-term warming. It is not a question of whether we can limit warming but whether we choose to do so. Our results elucidate important long-term HES dynamics that are often masked by common time-aggregated metrics. Aggressive near-term abatement will be very costly and do little to impact near-term warming. Conversely, the warming that will be experienced by future generations will mostly be driven by earlier abatement actions. We quantify probabilistic abatement pathways to tolerable climate/economic outcomes, conditional on the climate sensitivity to the atmospheric CO2 concentration. Even under optimistic assumptions about the climate sensitivity, pathways to a tolerable climate/economic future are rapidly narrowing.
How Global Warming Changes the Difficulty of Synoptic Weather Forecasting
S. Scher & G. Messori
Geophysical Research Letters, 16 March 2019, Pages 2931-2939
Abstract:
Global warming projections point to a wide range of impacts on the climate system, including changes in storm track activity and more frequent and intense extreme weather events. Little is however known on whether and how global warming may affect the atmosphere's predictability and thus our ability to produce accurate weather forecasts. Here, we combine a state‐of‐the‐art climate and a state‐of‐the‐art ensemble weather prediction model to show that, in a business‐as‐usual 21st century setting, global warming could significantly change the predictability of the atmosphere, defined here via the expected error of weather predictions. Predictability of synoptic weather situations could significantly increase, especially in the Northern Hemisphere. This can be explained by a decrease in the meridional temperature gradient. Contrarily, summertime predictability of weekly rainfall sums might significantly decrease in most regions.
Mid-latitude net precipitation decreased with Arctic warming during the Holocene
Cody Routson et al.
Nature, April 2019, Pages 83–87
Abstract:
The latitudinal temperature gradient between the Equator and the poles influences atmospheric stability, the strength of the jet stream and extratropical cyclones. Recent global warming is weakening the annual surface gradient in the Northern Hemisphere by preferentially warming the high latitudes; however, the implications of these changes for mid-latitude climate remain uncertain. Here we show that a weaker latitudinal temperature gradient — that is, warming of the Arctic with respect to the Equator — during the early to middle part of the Holocene coincided with substantial decreases in mid-latitude net precipitation (precipitation minus evapotranspiration, at 30° N to 50° N). We quantify the evolution of the gradient and of mid-latitude moisture both in a new compilation of Holocene palaeoclimate records spanning from 10° S to 90° N and in an ensemble of mid-Holocene climate model simulations. The observed pattern is consistent with the hypothesis that a weaker temperature gradient led to weaker mid-latitude westerly flow, weaker cyclones and decreased net terrestrial mid-latitude precipitation. Currently, the northern high latitudes are warming at rates nearly double the global average, decreasing the Equator-to-pole temperature gradient to values comparable with those in the early to middle Holocene. If the patterns observed during the Holocene hold for current anthropogenically forced warming, the weaker latitudinal temperature gradient will lead to considerable reductions in mid-latitude water resources.
Localized Changes in Heatwave Properties across the USA
Javad Shafiei Shiva, David Chandler & Kenneth Kunkel
Earth's Future, March 2019, Pages 300-319
Abstract:
Heatwaves are an important type of extreme climate event and directly result in more than 130 deaths per year across the USA. Heatwaves have been described by several attributes and combinations which constitute various event typologies. Attributes of heatwaves from ten cities are analyzed over the period 1950‐2016 to understand how these attributes determine variability in local heatwaves and how climate change affects heatwaves across the USA. This study uses eight definitions to differentiate heatwaves and tests for temporal trends in key properties of heatwaves over the period 1950‐2016. At least five harmful attributes of heatwaves have increased simultaneously for Dallas, Miami, New York, Phoenix, and Portland. Miami showed the greatest change in heatwave season length, frequency, and timing over the study period. Surprisingly, the greatest mean heatwave intensities above daily thresholds were for Bismarck, ND (+8.2 °C) and Syracuse, NY (+6.5 °C). Similar results across Baltimore, MD, Colorado Springs, CO, Dallas, TX, Des Moines, IA, Miami, FL, New York, NY, Phoenix, AZ, and Portland, OR, are presented to clarify the many quantitative differences in heatwave attributes and variance in quantification approaches across climates. This work explores the nexus of quantitative description and social construction of heatwaves through the lens of the various regional metrics to describe heatwaves. Ultimately, this assessment will guide the development of various strategies to help communities understand and prepare for heat resilience based on local heatwave components.
Arc-continent collisions in the tropics set Earth’s climate state
Francis Macdonald et al.
Science, 12 April 2019, Pages 181-184
Abstract:
On multimillion-year time scales, Earth has experienced warm ice-free and cold glacial climates, but it is unknown whether transitions between these background climate states were the result of changes in carbon dioxide sources or sinks. Low-latitude arc-continent collisions are hypothesized to drive cooling by exhuming and eroding mafic and ultramafic rocks in the warm, wet tropics, thereby increasing Earth’s potential to sequester carbon through chemical weathering. To better constrain global weatherability through time, the paleogeographic position of all major Phanerozoic arc-continent collisions was reconstructed and compared to the latitudinal distribution of ice sheets. This analysis reveals a strong correlation between the extent of glaciation and arc-continent collisions in the tropics. Earth’s climate state is set primarily by global weatherability, which changes with the latitudinal distribution of arc-continent collisions.