Our burning problem
Preferences for Domestic Action Over International Transfers in Global Climate Policy
Mark Buntaine & Lauren Prather
Journal of Experimental Political Science, forthcoming
Abstract:
Cost-effective and equitable climate change mitigation requires the transfer of resources from developed to developing countries. In two behavioral experiments, we demonstrate that American subjects act according to a strong home preference, by making private donations and writing letters in support of public spending more often for mitigation programs located at home versus those overseas. We attempt to overcome the preference to act at home by randomly informing some subjects that foreign programs are more cost-effective than domestic programs. Home preference is mitigated only in the case of private donations. From a separate experimental treatment, we show that the preference against foreign programs is exacerbated when the co-benefits of mitigation programs are made salient. Importantly, home preference crosses party lines, indicating that it is a deep-seeded, affective preference. These findings highlight significant political obstacles to international cooperation on climate change that relies on transfers.
What’s Wrong with Joyguzzling?
Ewan Kingston & Walter Sinnott-Armstrong
Ethical Theory and Moral Practice, February 2018, Pages 169–186
Abstract:
Our thesis is that there is no moral requirement to refrain from emitting reasonable amounts of greenhouse gases (GHGs) solely in order to enjoy oneself. Joyriding in a gas guzzler (joyguzzling) provides our paradigm example. We first distinguish this claim that there is no moral requirement to refrain from joyguzzling from other more radical claims. We then review several different proposed objections to our view. These include: the claim that joyguzzling exemplifies a vice, causes or contributes to harm, has negative expected value, exceeds our fair share of global emissions, and undermines political duties. We show why none of these objections succeeds and conclude that no good reason has yet been proposed that shows why joyguzzling violates a moral requirement.
Limited emission reductions from fuel subsidy removal except in energy-exporting regions
Jessica Jewell et al.
Nature, 8 February 2018, Pages 229–233
Abstract:
Hopes are high that removing fossil fuel subsidies could help to mitigate climate change by discouraging inefficient energy consumption and levelling the playing field for renewable energy. In September 2016, the G20 countries re-affirmed their 2009 commitment (at the G20 Leaders’ Summit) to phase out fossil fuel subsidies and many national governments are using today’s low oil prices as an opportunity to do so. In practical terms, this means abandoning policies that decrease the price of fossil fuels and electricity generated from fossil fuels to below normal market prices. However, whether the removal of subsidies, even if implemented worldwide, would have a large impact on climate change mitigation has not been systematically explored. Here we show that removing fossil fuel subsidies would have an unexpectedly small impact on global energy demand and carbon dioxide emissions and would not increase renewable energy use by 2030. Subsidy removal would reduce the carbon price necessary to stabilize greenhouse gas concentration at 550 parts per million by only 2–12 per cent under low oil prices. Removing subsidies in most regions would deliver smaller emission reductions than the Paris Agreement (2015) climate pledges and in some regions global subsidy removal may actually lead to an increase in emissions, owing to either coal replacing subsidized oil and natural gas or natural-gas use shifting from subsidizing, energy-exporting regions to non-subsidizing, importing regions. Our results show that subsidy removal would result in the largest CO2 emission reductions in high-income oil- and gas-exporting regions, where the reductions would exceed the climate pledges of these regions and where subsidy removal would affect fewer people living below the poverty line than in lower-income regions.
Divestment prevails over the green paradox when anticipating strong future climate policies
Nico Bauer et al.
Nature Climate Change, February 2018, Pages 130–134
Abstract:
Fossil fuel market dynamics will have a significant impact on the effectiveness of climate policies. Both fossil fuel owners and investors in fossil fuel infrastructure are sensitive to climate policies that threaten their natural resource endowments and production capacities, which will consequently affect their near-term behaviour. Although weak in near-term policy commitments, the Paris Agreement on climate signaled strong ambitions in climate change stabilization. Many studies emphasize that the 2 °C target can still be achieved even if strong climate policies are delayed until 2030. However, sudden implementation will have severe consequences for fossil fuel markets and beyond and these studies ignore the anticipation effects of owners and investors. Here we use two energy–economy models to study the collective influence of the two central but opposing anticipation arguments, the green paradox and the divestment effect, which have, to date, been discussed only separately. For a wide range of future climate policies, we find that anticipation effects, on balance, reduce CO2 emissions during the implementation lag. This is because of strong divestment in coal power plants starting ten years ahead of policy implementation. The green paradox effect is identified, but is small under reasonable assumptions.
Mirage on the Horizon: Geoengineering and Carbon Taxation Without Commitment
Daron Acemoglu & Will Rafey
MIT Working Paper, March 2018
Abstract:
We show that, in a model without commitment to future policies, geoengineering breakthroughs can have adverse environmental and welfare effects because they change the (equilibrium) carbon taxes. In our model, energy producers emit carbon, which creates a negative environmental externality, and may decide to switch to cleaner technology. A benevolent social planner sets carbon taxes without commitment. Higher future carbon taxes both reduce emissions given technology and encourage energy producers to switch to cleaner technology. Geoengineering advances, which reduce the negative environmental effects of the existing stock of carbon, decrease future carbon taxes and thus discourage private investments in conventional clean technology. We characterize the conditions under which these advances diminish — rather than improve — environmental quality and welfare.
Climate-change–driven accelerated sea-level rise detected in the altimeter era
Robert Nerem et al.
Proceedings of the National Academy of Sciences, 27 February 2018, Pages 2022-2025
Abstract:
Using a 25-y time series of precision satellite altimeter data from TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3, we estimate the climate-change–driven acceleration of global mean sea level over the last 25 y to be 0.084 ± 0.025 mm/y2. Coupled with the average climate-change–driven rate of sea level rise over these same 25 y of 2.9 mm/y, simple extrapolation of the quadratic implies global mean sea level could rise 65 ± 12 cm by 2100 compared with 2005, roughly in agreement with the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5) model projections.
A projected decrease in lightning under climate change
Declan Finney et al.
Nature Climate Change, March 2018, Pages 210–213
Abstract:
Lightning strongly influences atmospheric chemistry, and impacts the frequency of natural wildfires. Most previous studies project an increase in global lightning with climate change over the coming century, but these typically use parameterizations of lightning that neglect cloud ice fluxes, a component generally considered to be fundamental to thunderstorm charging. As such, the response of lightning to climate change is uncertain. Here, we compare lightning projections for 2100 using two parameterizations: the widely used cloud-top height (CTH) approach, and a new upward cloud ice flux (IFLUX) approach that overcomes previous limitations. In contrast to the previously reported global increase in lightning based on CTH, we find a 15% decrease in total lightning flash rate with IFLUX in 2100 under a strong global warming scenario. Differences are largest in the tropics, where most lightning occurs, with implications for the estimation of future changes in tropospheric ozone and methane, as well as differences in their radiative forcings. These results suggest that lightning schemes more closely related to cloud ice and microphysical processes are needed to robustly estimate future changes in lightning and atmospheric composition.
Dramatic declines in snowpack in the western US
Philip Mote et al.
npj Climate and Atmospheric Science, March 2018
Abstract:
Mountain snowpack stores a significant quantity of water in the western US, accumulating during the wet season and melting during the dry summers and supplying much of the water used for irrigated agriculture, and municipal and industrial uses. Updating our earlier work published in 2005, we find that with 14 additional years of data, over 90% of snow monitoring sites with long records across the western US now show declines, of which 33% are significant (vs. 5% expected by chance) and 2% are significant and positive (vs. 5% expected by chance). Declining trends are observed across all months, states, and climates, but are largest in spring, in the Pacific states, and in locations with mild winter climate. We corroborate and extend these observations using a gridded hydrology model, which also allows a robust estimate of total western snowpack and its decline. We find a large increase in the fraction of locations that posted decreasing trends, and averaged across the western US, the decline in average April 1 snow water equivalent since mid-century is roughly 15–30% or 25–50 km3, comparable in volume to the West’s largest man-made reservoir, Lake Mead.
Sustained climate warming drives declining marine biological productivity
Keith Moore et al.
Science, 9 March 2018, Pages 1139-1143
Abstract:
Climate change projections to the year 2100 may miss physical-biogeochemical feedbacks that emerge later from the cumulative effects of climate warming. In a coupled climate simulation to the year 2300, the westerly winds strengthen and shift poleward, surface waters warm, and sea ice disappears, leading to intense nutrient trapping in the Southern Ocean. The trapping drives a global-scale nutrient redistribution, with net transfer to the deep ocean. Ensuing surface nutrient reductions north of 30°S drive steady declines in primary production and carbon export (decreases of 24 and 41%, respectively, by 2300). Potential fishery yields, constrained by lower–trophic-level productivity, decrease by more than 20% globally and by nearly 60% in the North Atlantic. Continued high levels of greenhouse gas emissions could suppress marine biological productivity for a millennium.
Coral reefs will transition to net dissolving before end of century
Bradley Eyre et al.
Science, 23 February 2018, Pages 908-911
Abstract:
Ocean acidification refers to the lowering of the ocean’s pH due to the uptake of anthropogenic CO2 from the atmosphere. Coral reef calcification is expected to decrease as the oceans become more acidic. Dissolving calcium carbonate (CaCO3) sands could greatly exacerbate reef loss associated with reduced calcification but is presently poorly constrained. Here we show that CaCO3 dissolution in reef sediments across five globally distributed sites is negatively correlated with the aragonite saturation state (Ωar) of overlying seawater and that CaCO3 sediment dissolution is 10-fold more sensitive to ocean acidification than coral calcification. Consequently, reef sediments globally will transition from net precipitation to net dissolution when seawater Ωar reaches 2.92 ± 0.16 (expected circa 2050 CE). Notably, some reefs are already experiencing net sediment dissolution.
Unprecedented climate events: Historical changes, aspirational targets, and national commitments
Noah Diffenbaugh, Deepti Singh & Justin Mankin
Science Advances, February 2018
Abstract:
The United Nations Paris Agreement creates a specific need to compare consequences of cumulative emissions for pledged national commitments and aspirational targets of 1.5° to 2°C global warming. We find that humans have already increased the probability of historically unprecedented hot, warm, wet, and dry extremes, including over 50 to 90% of North America, Europe, and East Asia. Emissions consistent with national commitments are likely to cause substantial and widespread additional increases, including more than fivefold for warmest night over ~50% of Europe and >25% of East Asia and more than threefold for wettest days over >35% of North America, Europe, and East Asia. In contrast, meeting aspirational targets to keep global warming below 2°C reduces the area experiencing more than threefold increases to <10% of most regions studied. However, large areas — including >90% of North America, Europe, East Asia, and much of the tropics — still exhibit sizable increases in the probability of record-setting hot, wet, and/or dry events.
Committed sea-level rise under the Paris Agreement and the legacy of delayed mitigation action
Matthias Mengel et al.
Nature Communications, February 2018
Abstract:
Sea-level rise is a major consequence of climate change that will continue long after emissions of greenhouse gases have stopped. The 2015 Paris Agreement aims at reducing climate-related risks by reducing greenhouse gas emissions to net zero and limiting global-mean temperature increase. Here we quantify the effect of these constraints on global sea-level rise until 2300, including Antarctic ice-sheet instabilities. We estimate median sea-level rise between 0.7 and 1.2 m, if net-zero greenhouse gas emissions are sustained until 2300, varying with the pathway of emissions during this century. Temperature stabilization below 2 °C is insufficient to hold median sea-level rise until 2300 below 1.5 m. We find that each 5-year delay in near-term peaking of CO2 emissions increases median year 2300 sea-level rise estimates by ca. 0.2 m, and extreme sea-level rise estimates at the 95th percentile by up to 1 m. Our results underline the importance of near-term mitigation action for limiting long-term sea-level rise risks.
Regional Climate Impacts of Stabilizing Global Warming at 1.5 K Using Solar Geoengineering
Anthony Jones et al.
Earth's Future, forthcoming
Abstract:
The 2015 Paris Agreement aims to limit global warming to well below 2 K above preindustrial levels, and to pursue efforts to limit global warming to 1.5 K, in order to avert dangerous climate change. However, current greenhouse gas emissions targets are more compatible with scenarios exhibiting end-of-century global warming of 2.6–3.1 K, in clear contradiction to the 1.5 K target. In this study, we use a global climate model to investigate the climatic impacts of using solar geoengineering by stratospheric aerosol injection to stabilize global-mean temperature at 1.5 K for the duration of the 21st century against three scenarios spanning the range of plausible greenhouse gas mitigation pathways (RCP2.6, RCP4.5, and RCP8.5). In addition to stabilizing global mean temperature and offsetting both Arctic sea-ice loss and thermosteric sea-level rise, we find that solar geoengineering could effectively counteract enhancements to the frequency of extreme storms in the North Atlantic and heatwaves in Europe, but would be less effective at counteracting hydrological changes in the Amazon basin and North Atlantic storm track displacement. In summary, solar geoengineering may reduce global mean impacts but is an imperfect solution at the regional level, where the effects of climate change are experienced. Our results should galvanize research into the regionality of climate responses to solar geoengineering.
Climate change, agricultural production and civil conflict: Evidence from the Philippines
Benjamin Crost et al.
Journal of Environmental Economics and Management, March 2018, Pages 379-395
Abstract:
Using unique data on conflict-related incidents in the Philippines, we exploit seasonal variation in the relationship between rainfall and agricultural production to learn about the mechanism through which rainfall affects civil conflict. We find that an increase in dry-season rainfall leads to an increase in agricultural production and dampens conflict intensity. By contrast, an increase in wet-season rainfall is harmful to crops and produces more conflict. Consistent with the hypothesis that rebel groups gain strength after a bad harvest, we find that negative rainfall shocks lead to an increase in conflict incidents initiated by insurgents but not by government forces. These results suggest that the predicted shift towards wetter wet seasons and drier dry seasons will lead to more civil conflict even if annual rainfall totals remain stable. We conclude that policies aimed at mitigating the effect of climate change on agriculture could have the added benefit of reducing civil conflict.
Does reduced psychological distance increase climate engagement? On the limits of localizing climate change
Jonathon Schuldt, Laura Rickard & Janet Yang
Journal of Environmental Psychology, February 2018, Pages 147-153
Abstract:
It is commonly suggested that reducing the psychological distance of climate change will increase public engagement. However, extant studies are limited by their correlational design, or by depicting impacts that vary in distance but also in kind or severity. We conducted two experiments designed to vary distance only, holding impacts constant. U.S. participants completed a visual-spatial task that portrayed the Maldives — a remote island nation facing severe climate impacts — as relatively proximal or distal, before judging the nation's geographic distance (Studies 1 and 2) and summarizing a video depicting its climate vulnerabilities (Study 2). Suggesting an effect on psychological distance, participants in the proximal condition judged the Maldives as geographically closer and described its climate impacts using more concrete (vs. abstract) language. However, this reduced psychological distance did not translate into increased policy support. Complementing other work, results suggest that localizing climate change, by itself, is unlikely to increase engagement.
Avoided climate impacts of urban and rural heat and cold waves over the U.S. using large climate model ensembles for RCP8.5 and RCP4.5
Keith Oleson et al.
Climatic Change, February 2018, Pages 377–392
Abstract:
Previous studies examining future changes in heat/cold waves using climate model ensembles have been limited to grid cell-average quantities. Here, we make use of an urban parameterization in the Community Earth System Model (CESM) that represents the urban heat island effect, which can exacerbate extreme heat but may ameliorate extreme cold in urban relative to rural areas. Heat/cold wave characteristics are derived for U.S. regions from a bias-corrected CESM 30-member ensemble for climate outcomes driven by the RCP8.5 forcing scenario and a 15-member ensemble driven by RCP4.5. Significant differences are found between urban and grid cell-average heat/cold wave characteristics. Most notably, urban heat waves for 1981–2005 are more intense than grid cell-average by 2.1 °C (southeast) to 4.6 °C (southwest), while cold waves are less intense. We assess the avoided climate impacts of urban heat/cold waves in 2061–2080 when following the lower forcing scenario. Urban heat wave days per year increase from 6 in 1981–2005 to up to 92 (southeast) in RCP8.5. Following RCP4.5 reduces heat wave days by about 50 %. Large avoided impacts are demonstrated for individual communities; e.g., the longest heat wave for Houston in RCP4.5 is 38 days while in RCP8.5 there is one heat wave per year that is longer than a month with some lasting the entire summer. Heat waves also start later in the season in RCP4.5 (earliest are in early May) than RCP8.5 (mid-April), compared to 1981–2005 (late May). In some communities, cold wave events decrease from 2 per year for 1981–2005 to one-in-five year events in RCP4.5 and one-in-ten year events in RCP8.5.
Investment versus Output Subsidies: Implications of Alternative Incentives for Wind Energy
Joseph Aldy, Todd Gerarden & Richard Sweeney
NBER Working Paper, March 2018
Abstract:
This paper examines the choice between subsidizing investment or output to promote socially-desirable production. We exploit a natural experiment in which wind farm developers could choose an investment or output subsidy to estimate the impact of these instruments on productivity. Using regression discontinuity and matching estimators, we find that wind farms claiming the investment subsidy produced 10 to 11 percent less power than wind farms claiming the output subsidy, and that this effect reflects subsidy incentives rather than selection. The introduction of investment subsidies caused the Federal government to spend 12 percent more per unit of output from wind farms.
Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago: Ice Cores and Glaciers
Wendy Wolbach et al.
Journal of Geology, March 2018, Pages 165-184
Abstract:
The Younger Dryas boundary (YDB) cosmic-impact hypothesis is based on considerable evidence that Earth collided with fragments of a disintegrating ≥100-km-diameter comet, the remnants of which persist within the inner solar system ∼12,800 y later. Evidence suggests that the YDB cosmic impact triggered an “impact winter” and the subsequent Younger Dryas (YD) climate episode, biomass burning, late Pleistocene megafaunal extinctions, and human cultural shifts and population declines. The cosmic impact deposited anomalously high concentrations of platinum over much of the Northern Hemisphere, as recorded at 26 YDB sites at the YD onset, including the Greenland Ice Sheet Project 2 ice core, in which platinum deposition spans ∼21 y (∼12,836–12,815 cal BP). The YD onset also exhibits increased dust concentrations, synchronous with the onset of a remarkably high peak in ammonium, a biomass-burning aerosol. In four ice-core sequences from Greenland, Antarctica, and Russia, similar anomalous peaks in other combustion aerosols occur, including nitrate, oxalate, acetate, and formate, reflecting one of the largest biomass-burning episodes in more than 120,000 y. In support of widespread wildfires, the perturbations in CO2 records from Taylor Glacier, Antarctica, suggest that biomass burning at the YD onset may have consumed ∼10 million km2, or ∼9% of Earth’s terrestrial biomass. The ice record is consistent with YDB impact theory that extensive impact-related biomass burning triggered the abrupt onset of an impact winter, which led, through climatic feedbacks, to the anomalous YD climate episode.