Some Like it Hot
Addressing Global Warming Denialism: The Efficacy of Mechanism-Based Explanations in Changing Global Warming Beliefs
Jeff Rotman, T.J. Weber & Andrew Perkins
Public Opinion Quarterly, Spring 2020, Pages 74-103
Abstract:
Despite the scientific consensus concerning the current causes and future effects of anthropogenic global warming, there has been little to no improvement in public opinion, attitudes, or behavior related to its mitigation. This article examines how different information conveyance strategies affect belief in global warming. Three experiments reveal that a fundamental understanding of the underlying mechanism of global warming — the greenhouse gas effect — is integral to belief in the existence of global warming. Specifically, the current research demonstrates that persuasive messaging incorporating an explanation of the mechanism (versus consequences) underlying global warming leads to belief change (study 1); that this effect is moderated by political orientation, such that the effect of mechanism-understanding on global warming belief is greater for conservatives (study 1, 2, and 3); that understanding of the mechanism underlying global warming affects willingness to engage in sustainable activities and buying socially conscious products (study 2); and that the effect persists over time and can influence actual donation behavior (study 3). Social, public policy, and marketing implications for this strategy are discussed.
Party Cues in the News: Democratic Elites, Republican Backlash, and the Dynamics of Climate Skepticism
Eric Merkley & Dominik Stecula
British Journal of Political Science, forthcoming
Abstract:
Supporters of the Republican Party have become much more skeptical of the science of climate change since the 1990s. This article argues that out-group cues from Democratic elites caused a backlash that resulted in greater climate skepticism. The authors construct aggregate measures of climate skepticism from nearly 200 public opinion polls at the quarterly level from 2001 to 2014 and at the annual level from 1986 to 2014. They also build time-series measures of possible contributors to climate skepticism using an automated media content analysis. The analyses provide evidence that cues from party elites – especially from Democrats – are associated with aggregate dynamics in climate change skepticism, including among supporters of the Republican Party. The study also involves a party cue survey experiment administered to a sample of 3,000 Americans through Amazon Mechanical Turk to provide more evidence of causality. Together, these results highlight the importance of out-group cue taking and suggest that climate change skepticism should be examined through the lens of elite-led opinion formation.
Underwaterwriting: From theory to empiricism in regional mortgage markets in the U.S.
Jesse Keenan & Jacob Bradt
Climatic Change, forthcoming
Abstract:
This article provides the theoretical foundation for the concept of “Underwaterwriting,” which can be understood as various informational and institutional limitations related to environmental exposure and climate change impacts — specifically flooding and sea level rise inundation — shaping firm participation in mortgage markets. Underwaterwriting suggests that the unevenness of scientific knowledge and local soft information, as well as the institutional barriers for the utilization of that information, could result in determinations of risk that may not accurately reflect long-term asset performance or credit loss. These informational asymmetries may result in assignments of risk that reflect a degree of arbitrariness or inaccuracy that may operate to strand assets and shed or increase market share in ways that are inefficient and may otherwise lead to negative public externalities. Consistent with this theory, this article provides evidence that concentrated local lenders are transferring risk in high-risk coastal geographies in the Southeast Atlantic and Gulf Coasts (U.S.) through increased securitization of mortgages. These findings provide an impetus for supporting more robust analysis of climate-risk in light of forthcoming accounting rules that require an upfront accounting of forward-looking credit losses.
Coastal Flood Risk in the Mortgage Market: Storm Surge Models' Predictions vs. Flood Insurance Maps
Amine Ouazad
HEC Montreal Working Paper, May 2020
Abstract:
Prior literature has argued that flood insurance maps may not capture the extent of flood risk. This paper performs a granular assessment of coastal flood risk in the mortgage market by using physical simulations of hurricane storm surge heights instead of using FEMA's flood insurance maps. Matching neighborhood-level predicted storm surge heights with mortgage files suggests that coastal flood risk may be large: originations and securitizations in storm surge areas have been rising sharply since 2012, while they remain stable when using flood insurance maps. Every year, more than 50 billion dollars of originations occur in storm surge areas outside of insurance floodplains. The share of agency mortgages increases in storm surge areas, yet remains stable in the flood insurance 100-year floodplain. Mortgages in storm surge areas are more likely to be complex: non-fully amortizing features such as interest-only or adjustable rates. Households may also be more vulnerable in storm surge areas: median household income is lower, the share of African Americans and Hispanics is substantially higher, the share of individuals with health coverage is lower. Price-to-rent ratios are declining in storm surge areas while they are increasing in flood insurance areas. This paper suggests that uncovering future financial flood risk requires scientific models that are independent of the flood insurance mapping process.
Carbon Tail Risk
Emirhan Ilhan, Zacharias Sautner & Grigory Vilkov
Review of Financial Studies, forthcoming
Abstract:
Strong regulatory actions are needed to combat climate change, but climate policy uncertainty makes it difficult for investors to quantify the impact of future climate regulation. We show that such uncertainty is priced in the option market. The cost of option protection against downside tail risks is larger for firms with more carbon-intense business models. For carbon-intense firms, the cost of protection against downside tail risk is magnified at times when the public’s attention to climate change spikes, and it decreased after the election of climate change skeptic President Trump.
The Macroeconomic Impact of Europe's Carbon Taxes
Gilbert Metcalf & James Stock
NBER Working Paper, July 2020
Abstract:
Policy makers often express concern about the impact of carbon taxes on employment and GDP. Focusing on European countries that have implemented carbon taxes over the past 30 years, we estimate the macroeconomic impacts of these taxes on GDP and employment growth rates for various specifications and samples. Our point estimates suggest a zero to modest positive impact on GDP and total employment growth rates. More importantly, we find no robust evidence of a negative effect of the tax on employment or GDP growth. We examine evidence on whether the positive effects might stem from countries that used the carbon tax revenues to reduce other taxes; while the evidence is consistent with this view, it is inconclusive. We also consider the impact of the taxes on emission reductions and find a cumulative reduction on the order of 4 to 6 percent for a $40/ton CO2 tax covering 30% of emissions. We argue that reductions would likely be greater for a broad-based U.S. carbon tax since European carbon taxes do not include in the tax base those sectors with the lowest marginal costs of carbon pollution abatement.
Present-day greenhouse gases could cause more frequent and longer Dust Bowl heatwaves
Tim Cowan et al.
Nature Climate Change, June 2020, Pages 505–510
Abstract:
Substantial warming occurred across North America, Europe and the Arctic over the early twentieth century, including an increase in global drought, that was partially forced by rising greenhouse gases (GHGs). The period included the 1930s Dust Bowl drought across North America’s Great Plains that caused widespread crop failures, large dust storms and considerable out-migration. This coincided with the central United States experiencing its hottest summers of the twentieth century in 1934 and 1936, with over 40 heatwave days and maximum temperatures surpassing 44 °C at some locations. Here we use a large-ensemble regional modelling framework to show that GHG increases caused slightly enhanced heatwave activity over the eastern United States during 1934 and 1936. Instead of asking how a present-day heatwave would behave in a world without climate warming, we ask how these 1930s heatwaves would behave with present-day GHGs. Heatwave activity in similarly rare events would be much larger under today’s atmospheric GHG forcing and the return period of a 1-in-100-year heatwave summer (as observed in 1936) would be reduced to about 1-in-40 years. A key driver of the increasing heatwave activity and intensity is reduced evaporative cooling and increased sensible heating during dry springs and summers.
Potential for large-scale CO2 removal via enhanced rock weathering with croplands
David Beerling et al.
Nature, 9 July 2020, Pages 242–248
Abstract:
Enhanced silicate rock weathering (ERW), deployable with croplands, has potential use for atmospheric carbon dioxide (CO2) removal (CDR), which is now necessary to mitigate anthropogenic climate change. ERW also has possible co-benefits for improved food and soil security, and reduced ocean acidification. Here we use an integrated performance modelling approach to make an initial techno-economic assessment for 2050, quantifying how CDR potential and costs vary among nations in relation to business-as-usual energy policies and policies consistent with limiting future warming to 2 degrees Celsius5. China, India, the USA and Brazil have great potential to help achieve average global CDR goals of 0.5 to 2 gigatonnes of carbon dioxide (CO2) per year with extraction costs of approximately US$80–180 per tonne of CO2. These goals and costs are robust, regardless of future energy policies. Deployment within existing croplands offers opportunities to align agriculture and climate policy. However, success will depend upon overcoming political and social inertia to develop regulatory and incentive frameworks. We discuss the challenges and opportunities of ERW deployment, including the potential for excess industrial silicate materials (basalt mine overburden, concrete, and iron and steel slag) to obviate the need for new mining, as well as uncertainties in soil weathering rates and land–ocean transfer of weathered products.
Thermal bottlenecks in the life cycle define climate vulnerability of fish
Flemming Dahlke et al.
Science, 3 July 2020, Pages 65-70
Abstract:
Species’ vulnerability to climate change depends on the most temperature-sensitive life stages, but for major animal groups such as fish, life cycle bottlenecks are often not clearly defined. We used observational, experimental, and phylogenetic data to assess stage-specific thermal tolerance metrics for 694 marine and freshwater fish species from all climate zones. Our analysis shows that spawning adults and embryos consistently have narrower tolerance ranges than larvae and nonreproductive adults and are most vulnerable to climate warming. The sequence of stage-specific thermal tolerance corresponds with the oxygen-limitation hypothesis, suggesting a mechanistic link between ontogenetic changes in cardiorespiratory (aerobic) capacity and tolerance to temperature extremes. A logarithmic inverse correlation between the temperature dependence of physiological rates (development and oxygen consumption) and thermal tolerance range is proposed to reflect a fundamental, energetic trade-off in thermal adaptation. Scenario-based climate projections considering the most critical life stages (spawners and embryos) clearly identify the temperature requirements for reproduction as a critical bottleneck in the life cycle of fish. By 2100, depending on the Shared Socioeconomic Pathway (SSP) scenario followed, the percentages of species potentially affected by water temperatures exceeding their tolerance limit for reproduction range from ~10% (SSP 1–1.9) to ~60% (SSP 5–8.5). Efforts to meet ambitious climate targets (SSP 1–1.9) could therefore benefit many fish species and people who depend on healthy fish stocks.
Recent warming reduces the reproductive advantage of large size and contributes to evolutionary downsizing in nature
David Fryxell et al.
Proceedings of the Royal Society: Biological Sciences, June 2020
Abstract:
Body size is a key functional trait that is predicted to decline under warming. Warming is known to cause size declines via phenotypic plasticity, but evolutionary responses of body size to warming are poorly understood. To test for warming-induced evolutionary responses of body size and growth rates, we used populations of mosquitofish (Gambusia affinis) recently established (less than 100 years) from a common source across a strong thermal gradient (19–33°C) created by geothermal springs. Each spring is remarkably stable in temperature and is virtually closed to gene flow from other thermal environments. Field surveys show that with increasing site temperature, body size distributions become smaller and the reproductive advantage of larger body size decreases. After common rearing to reveal recently evolved trait differences, warmer-source populations expressed slowed juvenile growth rates and increased reproductive effort at small sizes. These results are consistent with an adaptive basis of the plastic temperature–size rule, and they suggest that temperature itself can drive the evolution of countergradient variation in growth rates. The rapid evolution of reduced juvenile growth rates and greater reproduction at a small size should contribute to substantial body downsizing in populations, with implications for population dynamics and for ecosystems in a warming world.
Ongoing AMOC and related sea-level and temperature changes after achieving the Paris targets
Michael Sigmond et al.
Nature Climate Change, July 2020, Pages 672–677
Abstract:
While the Atlantic Meridional Overturning Circulation (AMOC) is expected to weaken under increasing GHGs, it is unclear how it would respond to stabilization of global warming of 1.5 or 2.0 °C, the Paris Agreement temperature targets, or 3.0 °C, the expected warming by 2100 under current emission reduction policies. On the basis of stabilized warming simulations with two Earth System Models, we find that, after temperature stabilization, the AMOC declines for 5–10 years followed by a 150-year recovery to a level that is approximately independent of the considered stabilization scenario. The AMOC recovery has important implications for North Atlantic steric sea-level rise, which by 2600 is simulated to be 25–31% less than the global mean, and for North Atlantic surface temperatures, which continue to increase despite global mean surface temperature stabilization. These results show that substantial ongoing climate trends are likely to occur after global mean temperature has stabilized.