Out of This World

Kevin Lewis

June 15, 2022

Climate cooperation in the shadow of solar geoengineering: An experimental investigation of the moral hazard conjecture
Todd Cherry et al.
Environmental Politics, forthcoming 

As international efforts to mitigate greenhouse gases continue to fall short of global targets, the scientific community increasingly debates the role of solar geoengineering in climate policy. Given the infancy of these technologies, the debate is not yet whether to deploy solar geoengineering but whether solar geoengineering deserves consideration and research funding. Looming large over this discussion is the moral hazard conjecture -- normalizing solar geoengineering will decrease mitigation efforts. Using a controlled experiment of a collective-risk social dilemma that simulates the strategic decisions of heterogeneous groups to mitigate emissions and deploy solar geoengineering, we find no evidence for the moral hazard conjecture. On the contrary, when people in the experiment are given the option to deploy solar geoengineering, average investment in mitigation increases. 

Political ideology and psychological reactance: How serious should climate change be?
Eugene Chan & Jack Lin
Climatic Change, May 2022 

The divide in how people with different political views act upon climate change is evident, with conservatives generally less likely to take action to limit the effects of climate change. Typical communications aimed at conveying the importance of climate change and its effects on both the environment and human well-being typically stress the “seriousness” of such effects. In the current examination, we posit that using such adjectives can actually exacerbate the left–right divide. This is likely because, we propose, conservatives are higher on psychological reactance, and so they see communications conveying the “gravity” of climate change to be a limitation of their free will, thus producing the opposite behaviors of what such communications intend. We find support for our hypothesis in two studies with Americans with both dispositional as well as situational psychological reactance measures. Our results offer novel policy implications regarding by suggesting how a typical communication tactic could actually hamper the very aims of such communications. 

Reaching Science Skeptics: How Adaptive Framing of Climate Change Leads to Positive Responses Via Persuasion Knowledge and Perceived Behavioral Control
Renita Coleman et al.
Communication Research, forthcoming

This study extends framing theory by identifying two causal mechanisms and one contingent condition for a new type of frame to be used with issues where people dispute scientific claims. This new “adaptive frame” focuses on adapting to climate change impacts without cueing deeply held beliefs by discussing causes. An experiment shows this frame works by reducing persuasion knowledge and increasing perceived behavioral control, resulting in science skeptics being significantly more likely to intend to take action, engage with the news, and agree with the story’s perspective. This effect is moderated by science skepticism, with adaptive frames working significantly better on the very people the news media are not reaching. We contribute to theory with an understanding of how a frame that eliminates references to deep-seated beliefs is more effective than the existing frames of conflict, attribution of responsibility, and possibly others. 

Decarbonization and Electrification in the Long Run
Stephen Holland, Erin Mansur & Andrew Yates
NBER Working Paper, May 2022

Decarbonization and electrification will require a transformed electricity grid. Our long-run model of entry and exit of generation and storage capacity captures crucial aspects of the electricity industry such as time-varying demand for electricity, intermittency of renewables, and intertemporal optimization of storage. We derive several theoretical possibilities that differ in surprising ways from short-run intuition: A carbon tax can increase electricity consumption; cheaper storage can decrease renewable capacity; cheaper renewables can increase carbon emissions; and an increase in electricity demand (e.g., electrification) can decrease emissions. We calibrate the model using 2019 hourly data on demand and renewable availability for thirteen regions covering the contiguous U.S. A carbon price of $150 or more essentially eliminates carbon emissions. Given a modest decarbonization goal, a renewable subsidy performs better than a nuclear subsidy, but this ranking is reversed for an ambitious decarbonization goal. Transmission expansion yields large emissions reductions if renewable costs fall sufficiently, but policies promoting storage are unlikely to yield significant benefits. Electrifying 100% of car miles traveled (thereby eliminating gasoline vehicle carbon emissions) increases electricity-sector carbon emissions by 23-27% if vehicles are charged at night, but could decrease electricity-sector carbon emissions if vehicles are charged during the day.

Adapting to Flood Risk: Evidence from a Panel of Global Cities
Sahil Gandhi et al.
NBER Working Paper, June 2022

Urban flooding poses danger to people and places. People can adapt to this risk by moving to safer areas or by investing in private self-protection. Places can offset some of the risk through urban planning and infrastructure investment. By constructing a global city data set that covers the years 2012 to 2018, we test several flood risk adaptation hypotheses. Population growth is lower in cities that suffer from more floods. Richer cities suffer fewer deaths from flood events. Over time, the death toll from floods is declining. Cities protected by dams experience faster population growth. Using lights at night to measure short run urban economic dynamics, we document that floods cause less damage to richer cities and cities with protective dams. Cities with more past experience with floods suffer less from flooding.


Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals
Timothée Bonnet et al.
Science, 26 May 2022, Pages 1012-1016

The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change. 

Global record of “ghost” nannofossils reveals plankton resilience to high CO2 and warming
Sam Slater et al.
Science, 19 May 2022, Pages 853-856

Predictions of how marine calcifying organisms will respond to climate change rely heavily on the fossil record of nannoplankton. Declines in calcium carbonate (CaCO3) and nannofossil abundance through several past global warming events have been interpreted as biocalcification crises caused by ocean acidification and related factors. We present a global record of imprint -- or “ghost” -- nannofossils that contradicts this view, revealing exquisitely preserved nannoplankton throughout an inferred Jurassic biocalcification crisis. Imprints from two further Cretaceous warming events confirm that the fossil records of these intervals have been strongly distorted by CaCO3 dissolution. Although the rapidity of present-day climate change exceeds the temporal resolution of most fossil records, complicating direct comparison with past warming events, our findings demonstrate that nannoplankton were more resilient to past events than traditional fossil evidence suggests. 

Reduced global fire activity due to human demography slows global warming by enhanced land carbon uptake
Chao Wu et al.
Proceedings of the National Academy of Sciences, 17 May 2022

Fire is an important climate-driven disturbance in terrestrial ecosystems, also modulated by human ignitions or fire suppression. Changes in fire emissions can feed back on the global carbon cycle, but whether the trajectories of changing fire activity will exacerbate or attenuate climate change is poorly understood. Here, we quantify fire dynamics under historical and future climate and human demography using a coupled global climate–fire–carbon cycle model that emulates 34 individual Earth system models (ESMs). Results are compared with counterfactual worlds, one with a constant preindustrial fire regime and another without fire. Although uncertainty in projected fire effects is large and depends on ESM, socioeconomic trajectory, and emissions scenario, we find that changes in human demography tend to suppress global fire activity, keeping more carbon within terrestrial ecosystems and attenuating warming. Globally, changes in fire have acted to warm climate throughout most of the 20th century. However, recent and predicted future reductions in fire activity may reverse this, enhancing land carbon uptake and corresponding to offsetting ∼5 to 10 y of global CO2 emissions at today’s levels. This potentially reduces warming by up to 0.11 °C by 2100. We show that climate–carbon cycle feedbacks, as caused by changing fire regimes, are most effective at slowing global warming under lower emission scenarios. Our study highlights that ignitions and active and passive fire suppression can be as important in driving future fire regimes as changes in climate, although with some risk of more extreme fires regionally and with implications for other ecosystem functions in fire-dependent ecosystems.

Public Investment in Hazard Mitigation: Effectiveness and the Role of Community Diversity
Ivan Petkov
Northeastern University Working Paper, March 2022 

I estimate the loss-reducing effect of local public investments against natural hazards with new measures of damages, weather risk, and spending for a panel of 904 US coastal counties in 2000-2020. I distinguish federally- and county-funded projects and rely on a quasi-experimental strategy, matching counties by economic development, population, and weather risk. Risk predictions come from the Random Forest learning algorithm, using granular data on resident vulnerability and severe weather frequency. Public spending on adaptation is effective -- the average high-spending county avoids a significant portion of losses -- and efficient -- $1 prevents up to $3 in losses over 20 years. The evidence suggests that federal spending is focused on high-risk areas, while local spending is effectively implemented in medium-risk counties. Finally, I show that fractionalization among residents about the priority of climate-change policy can be a limiting factor in adaptation spending. Total spending is significantly lower in areas with high diversity in policy preferences, and more so when opinions are equally split.


Nuclear waste from small modular reactors
Lindsay Krall, Allison Macfarlane & Rodney Ewing
Proceedings of the National Academy of Sciences, 7 June 2022

Small modular reactors (SMRs; i.e., nuclear reactors that produce <300 MWelec each) have garnered attention because of claims of inherent safety features and reduced cost. However, remarkably few studies have analyzed the management and disposal of their nuclear waste streams. Here, we compare three distinct SMR designs to an 1,100-MWelec pressurized water reactor in terms of the energy-equivalent volume, (radio-)chemistry, decay heat, and fissile isotope composition of (notional) high-, intermediate-, and low-level waste streams. Results reveal that water-, molten salt–, and sodium-cooled SMR designs will increase the volume of nuclear waste in need of management and disposal by factors of 2 to 30. The excess waste volume is attributed to the use of neutron reflectors and/or of chemically reactive fuels and coolants in SMR designs. That said, volume is not the most important evaluation metric; rather, geologic repository performance is driven by the decay heat power and the (radio-)chemistry of spent nuclear fuel, for which SMRs provide no benefit. SMRs will not reduce the generation of geochemically mobile 129I, 99Tc, and 79Se fission products, which are important dose contributors for most repository designs. In addition, SMR spent fuel will contain relatively high concentrations of fissile nuclides, which will demand novel approaches to evaluating criticality during storage and disposal. Since waste stream properties are influenced by neutron leakage, a basic physical process that is enhanced in small reactor cores, SMRs will exacerbate the challenges of nuclear waste management and disposal.

Improving biodiversity protection through artificial intelligence
Daniele Silvestro et al.
Nature Sustainability, May 2022, Pages 415–424

Over a million species face extinction, highlighting the urgent need for conservation policies that maximize the protection of biodiversity to sustain its manifold contributions to people’s lives. Here we present a novel framework for spatial conservation prioritization based on reinforcement learning that consistently outperforms available state-of-the-art software using simulated and empirical data. Our methodology, conservation area prioritization through artificial intelligence (CAPTAIN), quantifies the trade-off between the costs and benefits of area and biodiversity protection, allowing the exploration of multiple biodiversity metrics. Under a limited budget, our model protects significantly more species from extinction than areas selected randomly or naively (such as based on species richness). CAPTAIN achieves substantially better solutions with empirical data than alternative software, meeting conservation targets more reliably and generating more interpretable prioritization maps. Regular biodiversity monitoring, even with a degree of inaccuracy characteristic of citizen science surveys, further improves biodiversity outcomes. Artificial intelligence holds great promise for improving the conservation and sustainable use of biological and ecosystem values in a rapidly changing and resource-limited world. 

Center Pivot Irrigation Systems as a Form of Drought Risk Mitigation in Humid Regions
Daniel Cooley & Steven Smith
NBER Working Paper, May 2022

Irrigation in the Eastern US receives little attention compared to the West, but farmers in humid states of the US, traditionally reliant on rainfall, have more than tripled irrigation since 1978. We examine this trend in Illinois where there has been a nearly threefold increase in center pivot irrigation systems (CPIS) installations since 1988. Specifically, we analyze where and when CPIS installations occur and their benefits in terms of annual crop yield, irrigated acreage, crop selection, and reduction in drought-related insurance payouts. To do so, we create a novel data set derived from a deep learning model capable of automatically identifying the location of CPIS during drought years along with annual county level crop, weather, and insurance data. The results indicate CPIS installations in Illinois are significantly more common over alluvial aquifers after droughts. Additionally, counties with a higher presence of CPIS do not have higher average crop yields, a shift to more water intensive crops, or an expansion of cropland. However, in drought years CPIS presence does have a significant positive effect on corn yield and a significant negative effect on indemnity payments for both soybeans and corn. The results provide insights into an emerging trend of irrigation in humid regions, raising potential policy considerations for crop insurance and signaling a potential need to address water rights as demand increases.


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