Raining down

Kevin Lewis

October 10, 2018

Precipitation reduction during Hurricane Harvey with simulated offshore wind farms
Yang Pan, Chi Yan & Cristina Archer
Environmental Research Letters, July 2018 


Hurricane Harvey brought to the Texas coast possibly the heaviest rain ever recorded in US history, which then caused flooding at unprecedented levels. Previous studies have shown that large arrays of hypothetical offshore wind farms can extract kinetic energy from a hurricane and thus reduce the wind and storm surge. This study quantitatively tests whether the hypothetical offshore turbines may also affect precipitation patterns. The Weather Research Forecast model is employed to model Harvey and the offshore wind farms are parameterized as elevated drag and turbulent kinetic energy sources. Model results indicate that the offshore wind farms have a strong impact on the distribution of accumulated precipitation, with an obvious decrease onshore downstream of the wind farms, and an increase in offshore areas, upstream of or within the wind farms. Compared with the control case with no wind turbines, increased horizontal wind divergence and lower vertical velocity are found where precipitation is reduced onshore, whereas increased horizontal wind convergence and higher vertical velocity occur upstream of or within the offshore wind farms. The sensitivity to the size of the offshore array, inter-turbine spacing, and the details of the wind farm parameterization are assessed. The results suggest that large arrays of offshore wind turbines can effectively protect the coast from heavy rain during hurricanes and that smart layouts with fewer turbines over smaller areas can be almost as effective as those with more turbines over larger areas.

Would it be Better to Not Talk about Climate Change? The Impact of Climate Change and Air Pollution Frames on Support for Regulating Power Plant Emissions
Sol Hart & Lauren Feldman
Journal of Environmental Psychology, December 2018, Pages 1-8


This study examined how utilizing different frames to contextualize negative impacts of power plant emissions influenced belief in those impacts and support for policies to regulate emissions. Using a U.S. national YouGov sample (n=1,000), we examined how discussing emissions in terms of climate change or air pollution, and in terms of health or environmental impacts, influenced individuals with different partisan affiliations. The analysis utilized a moderated-mediation model, with belief in negative impacts of power plant emissions as the mediator, support for government action as the dependent variable, and political party as a moderator of the link from the message frame to belief. This analysis revealed that using a climate change frame relative to an air pollution frame lowered policy support both directly and indirectly via belief in negative impacts, with the strongest indirect effect observed for Republicans. There were no effects of discussing environmental versus health impacts. The results suggest that communicators may be more successful in increasing support for mitigating carbon pollution from power plants by focusing on non-climate change oriented risks that the pollution poses, rather than linking the pollution to climate change.

Empirical evidence of mental health risks posed by climate change
Nick Obradovich et al.
Proceedings of the National Academy of Sciences, forthcoming


Sound mental health — a critical facet of human wellbeing — has the potential to be undermined by climate change. Few large-scale studies have empirically examined this hypothesis. Here, we show that short-term exposure to more extreme weather, multiyear warming, and tropical cyclone exposure each associate with worsened mental health. To do so, we couple meteorological and climatic data with reported mental health difficulties drawn from nearly 2 million randomly sampled US residents between 2002 and 2012. We find that shifting from monthly temperatures between 25 °C and 30 °C to >30 °C increases the probability of mental health difficulties by 0.5% points, that 1°C of 5-year warming associates with a 2% point increase in the prevalence of mental health issues, and that exposure to Hurricane Katrina associates with a 4% point increase in this metric. Our analyses provide added quantitative support for the conclusion that environmental stressors produced by climate change pose threats to human mental health.

How robust is the renewable energy industry to political shocks? Evidence from the 2016 U.S. elections
Michaël Aklin
Business and Politics, forthcoming


Climate change mitigation relies increasingly on clean technologies such as renewable energy. Despite widespread success, further deployment of renewables has been met with resistance from voters and governments in several countries. How resilient is the renewable energy industry to adverse political events? I use the unexpected election of Donald Trump in the 2016 U.S. presidential race to study this question. As a vocal critic of renewables and a supporter of fossil fuels, his election is a plausible negative shock to the renewable energy sector. I examine stock market data to gauge the reaction of investors. I find that renewable energy stocks were adversely affected by the election. Overall, they experienced a cumulative abnormal loss in share values of about 6 percent on average over the twenty days that followed the election. However, I find that the negative effect is concentrated among non-U.S. firms. U.S. firms, on average, emerged unscathed. Non-U.S. companies, on the other hand, lost over 14 percent of their value in the aftermath of the election. This suggests that markets are more concerned by increasing obstacles to international business than a decrease of federal support for renewables.

Cross-national variation in determinants of climate change concern
Gregory Lewis, Risa Palm & Bo Feng
Environmental Politics, forthcoming


Our understanding of the determinants of public concern about climate change relies heavily on survey research in the United States. But can those findings be generalized to the rest of the world? Analysis of the Pew Research Center’s 2015 Global Attitudes Survey shows fairly similar patterns in the English-speaking Western democracies and, to a lesser extent, western Europe, but party identification and political ideology matter much less in most of the globe, and demographic factors have very different impacts. Female, younger, and less religious people tend to worry more about climate change in English-speaking Western democracies. In most of the world, however, concern is only weakly correlated with gender, rises with age and religiosity, and is more strongly correlated with education. A new measure of commitment to democratic values proved to be the most consistent predictor of concern globally.

Rapid coastal deoxygenation due to ocean circulation shift in the northwest Atlantic
Mariona Claret et al.
Nature Climate Change, October 2018, Pages 868–872


Global observations show that the ocean lost approximately 2% of its oxygen inventory over the past five decades, with important implications for marine ecosystems. The rate of change varies regionally, with northwest Atlantic coastal waters showing a long-term drop that vastly outpaces the global and North Atlantic basin mean deoxygenation rates. However, past work has been unable to differentiate the role of large-scale climate forcing from that of local processes. Here, we use hydrographic evidence to show that a Labrador Current retreat is playing a key role in the deoxygenation on the northwest Atlantic shelf. A high-resolution global coupled climate–biogeochemistry model reproduces the observed decline of saturation oxygen concentrations in the region, driven by a retreat of the equatorward-flowing Labrador Current and an associated shift towards more oxygen-poor subtropical waters on the shelf. The dynamical changes underlying the shift in shelf water properties are correlated with a slowdown in the simulated Atlantic Meridional Overturning Circulation (AMOC). Our results provide strong evidence that a major, centennial-scale change of the Labrador Current is underway, and highlight the potential for ocean dynamics to impact coastal deoxygenation over the coming century.

Country-level social cost of carbon
Katharine Ricke et al.
Nature Climate Change, October 2018, Pages 895–900


The social cost of carbon (SCC) is a commonly employed metric of the expected economic damages from carbon dioxide (CO2) emissions. Although useful in an optimal policy context, a world-level approach obscures the heterogeneous geography of climate damage and vast differences in country-level contributions to the global SCC, as well as climate and socio-economic uncertainties, which are larger at the regional level. Here we estimate country-level contributions to the SCC using recent climate model projections, empirical climate-driven economic damage estimations and socio-economic projections. Central specifications show high global SCC values (median, US$417 per tonne of CO2 (tCO2); 66% confidence intervals, US$177–805 per tCO2) and a country-level SCC that is unequally distributed. However, the relative ranking of countries is robust to different specifications: countries that incur large fractions of the global cost consistently include India, China, Saudi Arabia and the United States.

Disproportionate magnitude of climate change in United States national parks
Patrick Gonzalez et al.
Environmental Research Letters, September 2018


Anthropogenic climate change is altering ecological and human systems globally, including in United States (US) national parks, which conserve unique biodiversity and resources. Yet, the magnitude and spatial patterns of climate change across all the parks have been unknown. Here, in the first spatial analysis of historical and projected temperature and precipitation across all 417 US national parks, we show that climate change exposes the national park area more than the US as a whole. This occurs because extensive parts of the national park area are in the Arctic, at high elevations, or in the arid southwestern US. Between 1895 and 2010, mean annual temperature of the national park area increased 1.0 °C ± 0.2 °C century−1 (mean ± standard error), double the US rate. Temperature has increased most in Alaska and its extensive national parks. Annual precipitation of the national park area declined significantly on 12% of national park area, compared to 3% of the US. Higher temperatures due to climate change have coincided with low precipitation in the southwestern US, intensifying droughts in the region. Physical and ecological changes have been detected and attributed mainly to anthropogenic climate change in areas of significant temperature increases in US national parks. From 2000 to 2100, under the highest emissions scenario (representative concentration pathway [RCP] 8.5), park temperatures would increase 3 °C–9 °C, with climate velocities outpacing dispersal capabilities of many plant and animal species. Even under the scenario of reduced emissions (RCP2.6), temperature increases could exceed 2 °C for 58% of national park area, compared to 22% of the US. Nevertheless, greenhouse gas emissions reductions could reduce projected temperature increases in national parks by one-half to two-thirds.

Increase in crop losses to insect pests in a warming climate
Curtis Deutsch et al.
Science, 31 August 2018, Pages 916-919


Insect pests substantially reduce yields of three staple grains — rice, maize, and wheat — but models assessing the agricultural impacts of global warming rarely consider crop losses to insects. We use established relationships between temperature and the population growth and metabolic rates of insects to estimate how and where climate warming will augment losses of rice, maize, and wheat to insects. Global yield losses of these grains are projected to increase by 10 to 25% per degree of global mean surface warming. Crop losses will be most acute in areas where warming increases both population growth and metabolic rates of insects. These conditions are centered primarily in temperate regions, where most grain is produced.

North American weather regimes are becoming more persistent: Is Arctic amplification a factor?
Jennifer Francis, Natasa Skific & Stephen Vavrus
Geophysical Research Letters, forthcoming


Rapid Arctic warming is hypothesized to favor an increased persistence of regional weather patterns in the northern hemisphere [Francis and Vavrus 2012]. Persistent conditions can lead to drought, heatwaves, prolonged cold spells, and storminess that can cost millions of dollars in damage and disrupt societal and ecosystem norms. This study defines a new metric called long‐duration events (LDEs) ‐‐ conditions that endure at least 4 consecutive days ‐‐ and takes two independent approaches to assessing seasonal changes in weather‐pattern persistence over North America. One applies precipitation measurements at weather stations across the United States; the other is based on a cluster analysis of large‐scale, upper‐level atmospheric patterns. Both methods indicate an overall increase in LDEs. We also find that large‐scale patterns consistent with a warm Arctic exhibit an increased frequency of LDEs, suggesting that further Arctic warming may favor persistent weather patterns that can lead to weather extremes.

Climate change is the world's greatest threat – In celsius or fahrenheit?
Eugene Chan
Journal of Environmental Psychology, December 2018, Pages 21-26


In two experiments, participants who were told that the Earth's average temperature was −24 °C thought that it was more important to limit climate change than those who were told that it was −16 °C. However, participants who were told that the average temperature was −11 °F thought it was less important to reduce the carbon footprint than those who were told that it was 3 °F. The findings contradict each other since −24 °C is the same as −11 °F, and −16 °C is the same as 3 °F. We draw on research on numerosity and goal-pursuit from behavioral psychology to explain the intriguingly-opposite findings. We measure both the perceived influence of and actual behavior to help fight climate change. Thus, we offer the novel hypothesis that presenting climate change figures in Celsius or Fahrenheit—two primary units to communicate temperature—can influence people's belief in or concern regarding climate change.

Exporting Pollution
Itzhak Ben-David, Stefanie Kleimeier & Michael Viehs
NBER Working Paper, October 2018


Despite awareness of the detrimental impact of CO2 pollution on the world climate, countries vary widely in how they design and enforce environmental laws. Using novel micro data about firms’ CO2 emissions levels in their home and foreign countries, we document that firms headquartered in countries with strict environmental policies perform their polluting activities abroad in countries with relatively weaker policies. These effects are stronger for firms in high-polluting industries and with poor corporate governance characteristics. Although firms export pollution, they nevertheless emit less overall CO2 globally in response to strict environmental policies at home.

Projected increases and shifts in rain-on-snow flood risk over western North America
Keith Musselman et al.
Nature Climate Change, September 2018, Pages 808–812


Destructive and costly flooding can occur when warm storm systems deposit substantial rain on extensive snowcover, as observed in February 2017 with the Oroville Dam crisis in California. However, decision-makers lack guidance on how such rain-on-snow (ROS) flood risk may respond to climate change. Here, daily ROS events with flood-generating potential are simulated over western North America for a historical (2000–2013) and future (forced under Representative Concentration Pathway 8.5) period with the Weather Research and Forecasting model; 4 km resolution allows the basin-scale ROS flood risk to be assessed. In the warmer climate, we show that ROS becomes less frequent at lower elevations due to snowpack declines, particularly in warmer areas (for example, the Pacific maritime region). By contrast, at higher elevations where seasonal snowcover persists, ROS becomes more frequent due to a shift from snowfall to rain. Accordingly, the water available for runoff increases for 55% of western North American river basins, with corresponding increases in flood risk of 20–200%, the greatest changes of which are projected for the Sierra Nevada, the Colorado River headwaters and the Canadian Rocky Mountains. Thus, flood control and water resource planning must consider ROS to fully quantify changes in flood risk with anthropogenic warming.

Climatic and socioeconomic controls of future coastal flood risk in Europe
Michalis Vousdoukas et al.
Nature Climate Change, September 2018, Pages 776–780


Rising extreme sea levels (ESLs) and continued socioeconomic development in coastal zones will lead to increasing future flood risk along the European coastline. We present a comprehensive analysis of future coastal flood risk (CFR) for Europe that separates the impacts of global warming and socioeconomic development. In the absence of further investments in coastal adaptation, the present expected annual damage (EAD) of €1.25 billion is projected to increase by two to three orders of magnitude by the end of the century, ranging between 93 and €961 billion. The current expected annual number of people exposed (EAPE) to coastal flooding of 102,000 is projected to reach 1.52–3.65 million by the end of the century. Climate change is the main driver of the future rise in coastal flood losses, with the importance of coastward migration, urbanization and rising asset values rapidly declining with time. To keep future coastal flood losses constant relative to the size of the economy, flood defence structures need to be installed or reinforced to withstand increases in ESLs that range from 0.5 to 2.5 m.

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