Exhale
Will the Paris Accord Accelerate Climate Change?
Laurence Kotlikoff, Andrey Polbin & Andrey Zubarev
NBER Working Paper, October 2016
Abstract:
The 2015 Paris Accord is meant to control our planet’s rising temperature. But it may be doing the opposite in gradually, rather than immediately reducing CO2 emissions. The Accord effectively tells dirty-energy producers to "use it or lose it." This may be accelerating their extraction and burning of fossil fuels and, thereby, be permanently raising temperatures. Our paper uses a simple OLG model to illustrate this long-noted Green Paradox. Its framework treats climate damage as a negative externality imposed by today’s generations on tomorrow’s – an externality that is, in part, irreversible and can tip the climate to permanently higher temperatures. In our model, delaying abatement can lead to larger changes in climate than doing nothing, reducing welfare for all generations. In contrast, immediate policy action can raise welfare for all generations. Finally we question the standard use of infinitely-lived, single-agent models, which assume, unrealistically, intergenerational altruism in determining optimal abatement policy. Their prescriptions can differ, potentially dramatically, from those needed to correct the negative climate externality today’s generations are imposing on tomorrow’s.
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Hurricane Sandy’s flood frequency increasing from year 1800 to 2100
Ning Lin et al.
Proceedings of the National Academy of Sciences, 25 October 2016, Pages 12071–12075
Abstract:
Coastal flood hazard varies in response to changes in storm surge climatology and the sea level. Here we combine probabilistic projections of the sea level and storm surge climatology to estimate the temporal evolution of flood hazard. We find that New York City’s flood hazard has increased significantly over the past two centuries and is very likely to increase more sharply over the 21st century. Due to the effect of sea level rise, the return period of Hurricane Sandy’s flood height decreased by a factor of ∼3× from year 1800 to 2000 and is estimated to decrease by a further ∼4.4× from 2000 to 2100 under a moderate-emissions pathway. When potential storm climatology change over the 21st century is also accounted for, Sandy’s return period is estimated to decrease by ∼3× to 17× from 2000 to 2100.
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Cornelis van Kooten
Annual Review of Resource Economics, 2016, Pages 181-205
Abstract:
Many countries have incentivized wind power projects to reduce their reliance on fossil fuels for generating electricity. As shown in this review, the benefits and costs of integrating electricity from an intermittent wind source into a preexisting electricity grid depend on the operating protocols of the electricity system, the preexisting generation mix, wind profiles, and the nature of economic incentives. Electricity systems are discussed from generation through transmission and distribution to retail demand, including how wind energy impacts investment in marginal (peak time) generating assets. The discussion also examines issues that could limit the usefulness of wind power at the high penetration rates now envisioned: the inability to store electricity, the need for fast-responding backup-generating capacity, network instability, low-capacity factors, and inappropriate incentives. Overall, this review finds that the costs of wind power likely exceed the benefits and that there may be limits to the proportion of electricity that can be generated by wind.
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Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake
Trevor Keenan et al.
Nature Communications, November 2016
Abstract:
Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.
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Strategic Policy Choice in State-Level Regulation: The EPA's Clean Power Plan
James Bushnell et al.
American Economic Journal: Economic Policy, forthcoming
Abstract:
The EPA's Clean Power Plan sets goals for CO2 emission rate reductions by 2030 that vary substantially across states. States can choose the regulatory mechanism they use and whether or not to join with other states in implementing their goals. We analyze incentives to adopt rate standards versus cap-and-trade with theory and simulation. We show conditions where adoption of inefficient rate standards is a dominant strategy from both consumers' and generators' perspectives. Numerical simulations of the Western electricity system highlight incentives for uncoordinated policies that lower welfare and increase emissions relative to coordination.
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Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission
Dirk Notz & Julienne Stroeve
Science, 11 November 2016, Pages 747-750
Abstract:
Arctic sea ice is retreating rapidly, raising prospects of a future ice-free Arctic Ocean during summer. Since climate-model simulations of the sea-ice loss differ substantially, we here use a robust linear relationship between monthly-mean September sea-ice area and cumulative CO2 emissions to infer the future evolution of Arctic summer sea ice directly from the observational record. The observed linear relationship implies a sustained loss of 3 ± 0.3 m2 of September sea-ice area per metric ton of CO2 emission. Based on this sensitivity, Arctic sea-ice will be lost throughout September for an additional 1000 Gt of CO2 emissions. Most models show a lower sensitivity, which is possibly linked to an underestimation of the modeled increase in incoming longwave radiation and of the modeled Transient Climate Response.
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The Social Cost of Carbon Revisited
Robert Pindyck
NBER Working Paper, November 2016
Abstract:
An estimate of the social cost of carbon (SCC) is key to climate policy. But how should we estimate the SCC? A common approach is to use an integrated assessment model (IAM) to simulate time paths for the atmospheric CO2 concentration, its impact on global mean temperature, and the resulting reductions in GDP and consumption. I have argued that IAMs have serious deficiencies that make them poorly suited for this job, but what is the alternative? I present a more transparent approach to estimating an average SCC, which I argue is a more useful guide for policy than the marginal SCC derived from IAMs. I rely on a survey through which I elicit expert opinions regarding (1) the probabilities of alternative economic outcomes of climate change, including extreme outcomes such as a 20% or greater reduction in GDP, but not the particular causes of those outcomes; and (2) the reduction in emissions required to avert an extreme outcome. My estimate of the average SCC is the ratio of the present value of damages from an extreme outcome to the total emission reduction needed to avert such an outcome. I discuss the survey instrument, explain how experts were identified, and present results. I obtain SCC estimates of $200/mt or higher, but the variation across experts is large. Trimming outliers and focusing on experts who expressed a high degree of confidence in their answers yields lower SCCs, $80 to $100/mt.
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Alan Taylor et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Large wildfires in California cause significant socioecological impacts, and half of the federal funds for fire suppression are spent each year in California. Future fire activity is projected to increase with climate change, but predictions are uncertain because humans can modulate or even override climatic effects on fire activity. Here we test the hypothesis that changes in socioecological systems from the Native American to the current period drove shifts in fire activity and modulated fire–climate relationships in the Sierra Nevada. We developed a 415-y record (1600–2015 CE) of fire activity by merging a tree-ring–based record of Sierra Nevada fire history with a 20th-century record based on annual area burned. Large shifts in the fire record corresponded with socioecological change, and not climate change, and socioecological conditions amplified and buffered fire response to climate. Fire activity was highest and fire–climate relationships were strongest after Native American depopulation — following mission establishment (ca. 1775 CE) — reduced the self-limiting effect of Native American burns on fire spread. With the Gold Rush and Euro-American settlement (ca. 1865 CE), fire activity declined, and the strong multidecadal relationship between temperature and fire decayed and then disappeared after implementation of fire suppression (ca. 1904 CE). The amplification and buffering of fire–climate relationships by humans underscores the need for parameterizing thresholds of human- vs. climate-driven fire activity to improve the skill and value of fire–climate models for addressing the increasing fire risk in California.
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Future nuisance flooding at Boston caused by astronomical tides alone
Richard Ray & Grant Foster
Earth's Future, forthcoming
Abstract:
Sea level rise necessarily triggers more occurrences of minor, or nuisance, flooding events along coastlines, a fact well documented in recent studies. At some locations nuisance flooding can be brought about merely by high spring tides, independent of storms, winds, or other atmospheric conditions. Analysis of observed water levels at Boston indicates that tidal flooding began to occur there in 2011 and will become more frequent in subsequent years. A compilation of all predicted nuisance-flooding events, induced by astronomical tides alone, is presented through year 2050. The accuracy of the tide prediction is improved when several unusual properties of Gulf of Maine tides, including secular changes, are properly accounted for. Future mean sea-level rise at Boston cannot be predicted with comparable confidence, so two very different climate scenarios are adopted; both predict a large increase in the frequency and the magnitude of tidal flooding events.
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The U.S. Economy in WWII as a Model for Coping with Climate Change
Hugh Rockoff
NBER Working Paper, September 2016
Abstract:
During World War II the United States rapidly transformed its economy to cope with a wide range of scarcities, such as shortfalls in the amounts of ocean shipping, aluminum, rubber, and other raw materials needed for the war effort. This paper explores the mobilization to see whether it provides lessons about how the economy could be transformed to meet scarcities produced by climate change or other environmental challenges. It concludes that the success of the United States in overcoming scarcities during World War II without a major deterioration in living standards provides a basis for optimism that environmental challenges can be met, but that the unique political consensus that prevailed during the war limits the practical usefulness of the wartime model.
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Climate change is advancing spring onset across the U.S. national park system
William Monahan et al.
Ecosphere, October 2016
Abstract:
Many U.S. national parks are already at the extreme warm end of their historical temperature distributions. With rapidly warming conditions, park resource management will be enhanced by information on seasonality of climate that supports adjustments in the timing of activities such as treating invasive species, operating visitor facilities, and scheduling climate-related events (e.g., flower festivals and fall leaf-viewing). Seasonal changes in vegetation, such as pollen, seed, and fruit production, are important drivers of ecological processes in parks, and phenology has thus been identified as a key indicator for park monitoring. Phenology is also one of the most proximate biological responses to climate change. Here, we use estimates of start of spring based on climatically modeled dates of first leaf and first bloom derived from indicator plant species to evaluate the recent timing of spring onset (past 10–30 yr) in each U.S. natural resource park relative to its historical range of variability across the past 112 yr (1901–2012). Of the 276 high latitude to subtropical parks examined, spring is advancing in approximately three-quarters of parks (76%), and 53% of parks are experiencing “extreme” early springs that exceed 95% of historical conditions. Our results demonstrate how changes in climate seasonality are important for understanding ecological responses to climate change, and further how spatial variability in effects of climate change necessitates different approaches to management. We discuss how our results inform climate change adaptation challenges and opportunities facing parks, with implications for other protected areas, by exploring consequences for resource management and planning.
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Coastal sea level rise with warming above 2 °C
Svetlana Jevrejeva et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Two degrees of global warming above the preindustrial level is widely suggested as an appropriate threshold beyond which climate change risks become unacceptably high. This “2 °C” threshold is likely to be reached between 2040 and 2050 for both Representative Concentration Pathway (RCP) 8.5 and 4.5. Resulting sea level rises will not be globally uniform, due to ocean dynamical processes and changes in gravity associated with water mass redistribution. Here we provide probabilistic sea level rise projections for the global coastline with warming above the 2 °C goal. By 2040, with a 2 °C warming under the RCP8.5 scenario, more than 90% of coastal areas will experience sea level rise exceeding the global estimate of 0.2 m, with up to 0.4 m expected along the Atlantic coast of North America and Norway. With a 5 °C rise by 2100, sea level will rise rapidly, reaching 0.9 m (median), and 80% of the coastline will exceed the global sea level rise at the 95th percentile upper limit of 1.8 m. Under RCP8.5, by 2100, New York may expect rises of 1.09 m, Guangzhou may expect rises of 0.91 m, and Lagos may expect rises of 0.90 m, with the 95th percentile upper limit of 2.24 m, 1.93 m, and 1.92 m, respectively. The coastal communities of rapidly expanding cities in the developing world, and vulnerable tropical coastal ecosystems, will have a very limited time after midcentury to adapt to sea level rises unprecedented since the dawn of the Bronze Age.
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Economic tools to promote transparency and comparability in the Paris Agreement
Joseph Aldy et al.
Nature Climate Change, November 2016, Pages 1000–1004
Abstract:
The Paris Agreement culminates a six-year transition towards an international climate policy architecture based on parties submitting national pledges every five years. An important policy task will be to assess and compare these contributions. We use four integrated assessment models to produce metrics of Paris Agreement pledges, and show differentiated effort across countries: wealthier countries pledge to undertake greater emission reductions with higher costs. The pledges fall in the lower end of the distributions of the social cost of carbon and the cost-minimizing path to limiting warming to 2 °C, suggesting insufficient global ambition in light of leaders’ climate goals. Countries’ marginal abatement costs vary by two orders of magnitude, illustrating that large efficiency gains are available through joint mitigation efforts and/or carbon price coordination. Marginal costs rise almost proportionally with income, but full policy costs reveal more complex regional patterns due to terms of trade effects.
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Meri Davlasheridze, Karen Fisher-Vanden & Allen Klaiber
Journal of Environmental Economics and Management, January 2017, Pages 93–114
Abstract:
This paper evaluates the relative effectiveness of FEMA expenditures on hurricane induced property losses. We find that spending on FEMA ex-ante mitigation and planning projects leads to greater reductions in property losses than spending on ex-post adaptation programs — specifically, a one percent increase in annual spending on ex-ante risk reduction and warning projects reduces damages by 0.21 percent while a one percent increase in ex-post recovery and clean-up spending reduces damages by 0.12. Although both types of program spending are effective, we find the marginal return from spending on programs that target long-term mitigation and risk management to be almost twice that of spending on ex-post recovery programs. With the predicted increases in the frequency and severity of North Atlantic hurricanes in the future, our findings suggest there are important potential gains that could be realized from the further diversification of FEMA spending across project categories.
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Impact of anthropogenic climate change on wildfire across western US forests
John Abatzoglou & Park Williams
Proceedings of the National Academy of Sciences, 18 October 2016, Pages 11770–11775
Abstract:
Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000–2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ∼55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984–2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.
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Telework: Urban Form, Energy Consumption, and Greenhouse Gas Implications
William Larson & Weihua Zhao
Economic Inquiry, forthcoming
Abstract:
A primary motivation of telework policy is to reduce energy consumption and greenhouse gas emissions. Using a numerical simulation of the standard urban model, we show telework causes sprawl, calling into question the idea that telework decreases energy consumption. Overall effects depend on wage changes due to telework, land-use regulation such as height limits or greenbelts, and the telework participation rate. While energy consumption increases in some scenarios, emissions may fall due to changes in the energy mix between gasoline and other sources.
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Don Grant & Ion Bogdan Vasi
Sociological Forum, forthcoming
Abstract:
Institutional scholars have argued that in the absence of legislation on the issue of climate change, nongovernmental organizations (NGOs) can help reduce the amount of anthropogenic greenhouse gases being emitted to the environment by disseminating environmental norms. Consistent with this reasoning, they have shown that from the middle of the last century up through the mid-1990s, nations with more memberships in NGOs have tended to have lower carbon dioxide (CO2) emissions in the aggregate. Doubts remain, however, about whether NGOs have reduced emissions in the time since and at the level of individual power plants where the lion's share of carbon pollution is emitted. Using plant-specific information on CO2 emissions recently collected by the Environmental Protection Agency (EPA) under its Greenhouse Gas Reporting Program, we investigate the effects of local environmental NGOs (ENGOs) on plants’ environmental performance. Consistent with our expectations, we find that local ENGOs not only directly reduce plants’ emissions but indirectly do so by enhancing the effectiveness of subnational climate policies that encourage energy efficiency. We discuss the implications of our findings for research on the decoupling of normative systems, social movements, environmental sociology, and the EPA's proposed Clean Power Plan.
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Toby Ault et al.
Science Advances, October 2016
Abstract:
Megadroughts are comparable in severity to the worst droughts of the 20th century but are of much longer duration. A megadrought in the American Southwest would impose unprecedented stress on the limited water resources of the area, making it critical to evaluate future risks not only under different climate change mitigation scenarios but also for different aspects of regional hydroclimate. We find that changes in the mean hydroclimate state, rather than its variability, determine megadrought risk in the American Southwest. Estimates of megadrought probabilities based on precipitation alone tend to underestimate risk. Furthermore, business-as-usual emissions of greenhouse gases will drive regional warming and drying, regardless of large precipitation uncertainties. We find that regional temperature increases alone push megadrought risk above 70, 90, or 99% by the end of the century, even if precipitation increases moderately, does not change, or decreases, respectively. Although each possibility is supported by some climate model simulations, the latter is the most common outcome for the American Southwest in Coupled Model Intercomparison 5 generation models. An aggressive reduction in global greenhouse gas emissions cuts megadrought risks nearly in half.
https://www.ncbi.nlm.nih.gov/pubmed/27790992