The weather outside is frightful
Past-focused environmental comparisons promote proenvironmental outcomes for conservatives
Matthew Baldwin & Joris Lammers
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Conservatives appear more skeptical about climate change and global warming and less willing to act against it than liberals. We propose that this unwillingness could result from fundamental differences in conservatives’ and liberals’ temporal focus. Conservatives tend to focus more on the past than do liberals. Across six studies, we rely on this notion to demonstrate that conservatives are positively affected by past- but not by future-focused environmental comparisons. Past comparisons largely eliminated the political divide that separated liberal and conservative respondents’ attitudes toward and behavior regarding climate change, so that across these studies conservatives and liberals were nearly equally likely to fight climate change. This research demonstrates how psychological processes, such as temporal comparison, underlie the prevalent ideological gap in addressing climate change. It opens up a promising avenue to convince conservatives effectively of the need to address climate change and global warming.
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Population Growth and Carbon Emissions
Gregory Casey & Oded Galor
NBER Working Paper, December 2016
Abstract:
We provide evidence that lower fertility can simultaneously increase income per capita and lower carbon emissions, eliminating a trade-off central to most policies aimed at slowing global climate change. We estimate the effect of lower fertility on carbon emissions accounting for the fact that changes in fertility patterns affect carbon emissions through three channels: total population, the age structure of the population, and economic output. Our analysis proceeds in two steps. First, we estimate a version of the STIRPAT equation on an unbalanced yearly panel of cross-country data from 1950-2010. We demonstrate that the coefficient on population is nearly seven times larger than the coefficient on income per capita and that this difference is statistically significant. Thus, regression results imply that 1% slower population growth could be accompanied by an increase in income per capita of nearly 7% while still lowering carbon emissions. In the second part of our analysis, we use a recently constructed economic-demographic model of Nigeria to estimate the effect of lower fertility on carbon emissions accounting for the impacts of fertility on population growth, population age structure, and income per capita. The model was constructed to estimate the effect of lower fertility on economic growth, making it well-suited for this application. We find that by 2100 C.E., moving from the medium to the low variant of the UN fertility projection leads to 35% lower yearly emissions and 15% higher income per capita. These results suggest that population policies could be a part of the approach to combating global climate change.
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Scott Hoover & Stephan Fafatas
Journal of Public Affairs, forthcoming
Abstract:
We investigate whether the political leaning of the state where a given firm is headquartered is related to that firm's decision to voluntarily disclose climate change information. We study S&P 500 firms that were surveyed by the Carbon Disclosure Project (CDP) and find that firms headquartered in more Democratic states are more likely to disclose carbon emissions information to the CDP. Furthermore, firms in more Democratic states are more likely to permit public disclosure of their survey responses and tend to receive higher disclosure scores. We consider two political variables, one based on political power and one based on public political preference. Our results are consistent with political power driving the firm's willingness to voluntarily disclose information about climate change. These results suggest that the relation between the political environment and disclosure is more closely linked to concerns over regulatory threats as opposed to acquiescence to social norms.
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How Large Are Global Fossil Fuel Subsidies?
David Coady et al.
World Development, March 2017, Pages 11–27
Abstract:
This paper estimates fossil fuel subsidies and the economic and environmental benefits from reforming them, focusing mostly on a broad notion of subsidies arising when consumer prices are below supply costs plus environmental costs and general consumption taxes. Estimated subsidies are $4.9 trillion worldwide in 2013 and $5.3 trillion in 2015 (6.5% of global GDP in both years). Undercharging for global warming accounts for 22% of the subsidy in 2013, air pollution 46%, broader vehicle externalities 13%, supply costs 11%, and general consumer taxes 8%. China was the biggest subsidizer in 2013 ($1.8 trillion), followed by the United States ($0.6 trillion), and Russia, the European Union, and India (each with about $0.3 trillion). Eliminating subsidies would have reduced global carbon emissions in 2013 by 21% and fossil fuel air pollution deaths 55%, while raising revenue of 4%, and social welfare by 2.2%, of global GDP.
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Projections and Uncertainties About Climate Change in an Era of Minimal Climate Policies
William Nordhaus
NBER Working Paper, December 2016
Abstract:
Climate change remains one of the major international environmental challenges facing nations. Yet nations have to date taken minimal policies to slow climate change. Moreover, there has been no major improvement in emissions trends as of the latest data. The current study uses the updated DICE model to present new projections and the impacts of alternative climate policies. It also presents a new set of estimates of the uncertainties about future climate change and compares the results will those of other integrated assessment models. The study confirms past estimates of likely rapid climate change over the next century if there are not major climate-change policies. It suggests that it will be extremely difficult to achieve the 2°C target of international agreements even if ambitious policies are introduced in the near term. The required carbon price needed to achieve current targets has risen over time as policies have been delayed.
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Spatial heterogeneity of climate change as an experiential basis for skepticism
Robert Kaufmann et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
We postulate that skepticism about climate change is partially caused by the spatial heterogeneity of climate change, which exposes experiential learners to climate heuristics that differ from the global average. This hypothesis is tested by formalizing an index that measures local changes in climate using station data and comparing this index with survey-based model estimates of county-level opinion about whether global warming is happening. Results indicate that more stations exhibit cooling and warming than predicted by random chance and that spatial variations in these changes can account for spatial variations in the percentage of the population that believes that “global warming is happening.” This effect is diminished in areas that have experienced more record low temperatures than record highs since 2005. Together, these results suggest that skepticism about climate change is driven partially by personal experiences; an accurate heuristic for local changes in climate identifies obstacles to communicating ongoing changes in climate to the public and how these communications might be improved.
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Overcoming endpoint bias in climate change communication: The case of Arctic sea ice trends
Bruce Hardy & Kathleen Hall Jamieson
Environmental Communication, forthcoming
Abstract:
Unusually cold winters, a slowing in upward global temperatures, or an increase in Arctic sea ice extent are often falsely cast as here-and-now disconfirmation of the scientific consensus on climate change. Such conclusions are examples of “end point bias,” the well documented psychological tendency to interpret a recent short-term fluctuation as a reversal of a long-term trend. End point bias poses a challenge to those trying to communicate cross-decade climate warming trends. In this study, we demonstrate that exposure to misleading scientific information on FoxNews.com that evokes end point bias can affect the beliefs of liberals and moderates as well as conservatives. We also show that the leveraging-involving-visualizing-analogizing communication model can reduce the effects of endpoint bias among moderates and liberals at the same time as it dampens both the ideological and endpoint biasing of conservatives.
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Global risk model for vector-borne transmission of Zika virus reveals the role of El Niño 2015
Cyril Caminade et al.
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Zika, a mosquito-borne viral disease that emerged in South America in 2015, was declared a Public Health Emergency of International Concern by the WHO in February of 2016. We developed a climate-driven R0 mathematical model for the transmission risk of Zika virus (ZIKV) that explicitly includes two key mosquito vector species: Aedes aegypti and Aedes albopictus. The model was parameterized and calibrated using the most up to date information from the available literature. It was then driven by observed gridded temperature and rainfall datasets for the period 1950–2015. We find that the transmission risk in South America in 2015 was the highest since 1950. This maximum is related to favoring temperature conditions that caused the simulated biting rates to be largest and mosquito mortality rates and extrinsic incubation periods to be smallest in 2015. This event followed the suspected introduction of ZIKV in Brazil in 2013. The ZIKV outbreak in Latin America has very likely been fueled by the 2015–2016 El Niño climate phenomenon affecting the region. The highest transmission risk globally is in South America and tropical countries where Ae. aegypti is abundant. Transmission risk is strongly seasonal in temperate regions where Ae. albopictus is present, with significant risk of ZIKV transmission in the southeastern states of the United States, in southern China, and to a lesser extent, over southern Europe during the boreal summer season.
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Impact of Electricity Pricing Policies on Renewable Energy Investments and Carbon Emissions
Gürhan Kök, Kevin Shang & Şafak Yücel
Management Science, forthcoming
Abstract:
We investigate the impact of pricing policies (i.e., flat pricing versus peak pricing) on the investment levels of a utility firm in two competing energy sources (renewable and conventional), with a focus on the renewable investment level. We consider generation patterns and intermittency of solar and wind energy in relation to the electricity demand throughout a day. Industry experts generally promote peak pricing policy as it smoothens the demand and reduces inefficiencies in the supply system. We find that the same pricing policy may lead to distinct outcomes for different renewable energy sources due to their generation patterns. Specifically, flat pricing leads to a higher investment level for solar energy, and it can lead to still more investments in wind energy if a considerable amount of wind energy is generated throughout the day. We validate these results by using electricity generation and demand data of the state of Texas. We also show that flat pricing can lead to substantially lower carbon emissions and a higher consumer surplus. Finally, we explore the effect of direct (e.g., tax credit) and indirect (e.g., carbon tax) subsidies on investment levels and carbon emissions. We show that both types of subsidies generally lead to a lower emission level but that indirect subsidies may result in lower renewable energy investments. Our study suggests that reducing carbon emissions through increasing renewable energy investments requires careful attention to the pricing policy and the market characteristics of each region.
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US daily temperature records past, present, and future
Gerald Meehl, Claudia Tebaldi & Dennis Adams-Smith
Proceedings of the National Academy of Sciences, 6 December 2016, Pages 13977–13982
Abstract:
Observed temperature extremes over the continental United States can be represented by the ratio of daily record high temperatures to daily record low minimum temperatures, and this ratio has increased to a value of about 2 to 1, averaged over the first decade of the 21st century, albeit with large interannual variability. Two different versions of a global coupled climate model (CCSM4), as well as 23 other coupled model intercomparison project phase 5 (CMIP5) models, show larger values of this ratio than observations, mainly as a result of greater numbers of record highs since the 1980s compared with observations. This is partly because of the “warm 1930s” in the observations, which made it more difficult to set record highs later in the century, and partly because of a trend toward less rainfall and reduced evapotranspiration in the model versions compared with observations. We compute future projections of this ratio on the basis of its estimated dependence on mean temperature increase, which we find robustly at play in both observations and simulations. The use of this relation also has the advantage of removing dependence of a projection on a specific scenario. An empirical projection of the ratio of record highs to record lows is obtained from the nonlinear relationship in observations from 1930 to 2015, thus correcting downward the likely biased future projections of the model. For example, for a 3 °C warming in US temperatures, the ratio of record highs to lows is projected to be ∼15 ± 8 compared to the present average ratio of just over 2.
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More tornadoes in the most extreme U.S. tornado outbreaks
Michael Tippett, Chiara Lepore & Joel Cohen
Science, 16 December 2016, Pages 1419-1423
Abstract:
Tornadoes and severe thunderstorms kill people and damage property every year. Estimated U.S. insured losses due to severe thunderstorms in the first half of 2016 were 8.5 billion USD. The largest U.S. impacts of tornadoes result from tornado outbreaks, which are sequences of tornadoes that occur in close succession. Here, using extreme value analysis, we find that the frequency of U.S. outbreaks with many tornadoes is increasing and is increasing faster for more extreme outbreaks. We model this behavior by extreme value distributions with parameters that are linear functions of time or of some indicators of multidecadal climatic variability. Extreme meteorological environments associated with severe thunderstorms show consistent upward trends, but the trends do not resemble those currently expected to result from global warming.
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The future intensification of hourly precipitation extremes
Andreas Prein et al.
Nature Climate Change, forthcoming
Abstract:
Extreme precipitation intensities have increased in all regions of the Contiguous United States (CONUS) and are expected to further increase with warming at scaling rates of about 7% per degree Celsius, suggesting a significant increase of flash flood hazards due to climate change. However, the scaling rates between extreme precipitation and temperature are strongly dependent on the region, temperature, and moisture availability, which inhibits simple extrapolation of the scaling rate from past climate data into the future. Here we study observed and simulated changes in local precipitation extremes over the CONUS by analysing a very high resolution (4 km horizontal grid spacing) current and high-end climate scenario that realistically simulates hourly precipitation extremes. We show that extreme precipitation is increasing with temperature in moist, energy-limited, environments and decreases abruptly in dry, moisture-limited, environments. This novel framework explains the large variability in the observed and modelled scaling rates and helps with understanding the significant frequency and intensity increases in future hourly extreme precipitation events and their interaction with larger scales.
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Persistent northward North Atlantic tropical cyclone track migration over the past five centuries
Lisa Baldini et al.
Scientific Reports, November 2016
Abstract:
Accurately predicting future tropical cyclone risk requires understanding the fundamental controls on tropical cyclone dynamics. Here we present an annually-resolved 450-year reconstruction of western Caribbean tropical cyclone activity developed using a new coupled carbon and oxygen isotope ratio technique in an exceptionally well-dated stalagmite from Belize. Western Caribbean tropical cyclone activity peaked at 1650 A.D., coincident with maximum Little Ice Age cooling, and decreased gradually until the end of the record in 1983. Considered with other reconstructions, the new record suggests that the mean track of Cape Verde tropical cyclones shifted gradually north-eastward from the western Caribbean toward the North American east coast over the last 450 years. Since ~1870 A.D., these shifts were largely driven by anthropogenic greenhouse gas and sulphate aerosol emissions. Our results strongly suggest that future emission scenarios will result in more frequent tropical cyclone impacts on the financial and population centres of the northeastern United States.
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Climate-Related Local Extinctions Are Already Widespread among Plant and Animal Species
John Wiens
PLoS Biology, December 2016
Abstract:
Current climate change may be a major threat to global biodiversity, but the extent of species loss will depend on the details of how species respond to changing climates. For example, if most species can undergo rapid change in their climatic niches, then extinctions may be limited. Numerous studies have now documented shifts in the geographic ranges of species that were inferred to be related to climate change, especially shifts towards higher mean elevations and latitudes. Many of these studies contain valuable data on extinctions of local populations that have not yet been thoroughly explored. Specifically, overall range shifts can include range contractions at the “warm edges” of species’ ranges (i.e., lower latitudes and elevations), contractions which occur through local extinctions. Here, data on climate-related range shifts were used to test the frequency of local extinctions related to recent climate change. The results show that climate-related local extinctions have already occurred in hundreds of species, including 47% of the 976 species surveyed. This frequency of local extinctions was broadly similar across climatic zones, clades, and habitats but was significantly higher in tropical species than in temperate species (55% versus 39%), in animals than in plants (50% versus 39%), and in freshwater habitats relative to terrestrial and marine habitats (74% versus 46% versus 51%). Overall, these results suggest that local extinctions related to climate change are already widespread, even though levels of climate change so far are modest relative to those predicted in the next 100 years. These extinctions will presumably become much more prevalent as global warming increases further by roughly 2-fold to 5-fold over the coming decades.
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Greenland was nearly ice-free for extended periods during the Pleistocene
Joerg Schaefer et al.
Nature, 8 December 2016, Pages 252–255
Abstract:
The Greenland Ice Sheet (GIS) contains the equivalent of 7.4 metres of global sea-level rise1. Its stability in our warming climate is therefore a pressing concern. However, the sparse proxy evidence of the palaeo-stability of the GIS means that its history is controversial (compare refs 2 and 3 to ref. 4). Here we show that Greenland was deglaciated for extended periods during the Pleistocene epoch (from 2.6 million years ago to 11,700 years ago), based on new measurements of cosmic-ray-produced beryllium and aluminium isotopes (10Be and 26Al) in a bedrock core from beneath an ice core near the GIS summit. Models indicate that when this bedrock site is ice-free, any remaining ice is concentrated in the eastern Greenland highlands and the GIS is reduced to less than ten per cent of its current volume. Our results narrow the spectrum of possible GIS histories: the longest period of stability of the present ice sheet that is consistent with the measurements is 1.1 million years, assuming that this was preceded by more than 280,000 years of ice-free conditions. Other scenarios, in which Greenland was ice-free during any or all Pleistocene interglacials, may be more realistic. Our observations are incompatible with most existing model simulations that present a continuously existing Pleistocene GIS. Future simulations of the GIS should take into account that Greenland was nearly ice-free for extended periods under Pleistocene climate forcing.
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The EU effect: Does trade with the EU reduce CO2 emissions in the developing world?
Aseem Prakash & Matthew Potoski
Environmental Politics, January/February 2017, Pages 27-48
Abstract:
The European Union (EU) is an important destination for developing country exports. Has the EU’s commitment to the Kyoto Protocol induced developing countries to reduce their carbon dioxide (CO2) emissions? Our analyses of 136 developing countries from 1981 through 2007 suggests that: developing countries’ export dependence on the EU is associated with CO2 emission reductions post-Kyoto in relation to the pre-Kyoto time period; this also holds for SO2, which, while not covered under Kyoto, is linked with CO2 emission levels; this does not hold for PM10, a pollutant which is not covered under Kyoto and is not directly associated with CO2 emissions related to industrial activities; developing countries’ export dependence on non-EU developed countries and on the rest of the world is not associated with significant reductions in emissions between pre- and post-Kyoto for these pollutants. In sum, even in the absence of binding regulatory mandates, the EU appears to exert market leverage to project its regulatory preferences abroad.
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The role of capital costs in decarbonizing the electricity sector
Lion Hirth & Jan Christoph Steckel
Environmental Research Letters, November 2016
Abstract:
Low-carbon electricity generation, i.e. renewable energy, nuclear power and carbon capture and storage, is more capital intensive than electricity generation through carbon emitting fossil fuel power stations. High capital costs, expressed as high weighted average cost of capital (WACC), thus tend to encourage the use of fossil fuels. To achieve the same degree of decarbonization, countries with high capital costs therefore need to impose a higher price on carbon emissions than countries with low capital costs. This is particularly relevant for developing and emerging economies, where capital costs tend to be higher than in rich countries. In this paper we quantitatively evaluate how high capital costs impact the transformation of the energy system under climate policy, applying a numerical techno-economic model of the power system. We find that high capital costs can significantly reduce the effectiveness of carbon prices: if carbon emissions are priced at USD 50 per ton and the WACC is 3%, the cost-optimal electricity mix comprises 40% renewable energy. At the same carbon price and a WACC of 15%, the cost-optimal mix comprises almost no renewable energy. At 15% WACC, there is no significant emission mitigation with carbon pricing up to USD 50 per ton, but at 3% WACC and the same carbon price, emissions are reduced by almost half. These results have implications for climate policy; carbon pricing might need to be combined with policies to reduce capital costs of low-carbon options in order to decarbonize power systems.
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Changes in Spatiotemporal Precipitation Patterns in Changing Climate Conditions
Won Chang et al.
Journal of Climate, December 2016, Pages 8355–8376
Abstract:
Climate models robustly imply that some significant change in precipitation patterns will occur. Models consistently project that the intensity of individual precipitation events increases by approximately 6%–7% K−1, following the increase in atmospheric water content, but that total precipitation increases by a lesser amount (1%–2% K−1 in the global average in transient runs). Some other aspect of precipitation events must then change to compensate for this difference. The authors develop a new methodology for identifying individual rainstorms and studying their physical characteristics — including starting location, intensity, spatial extent, duration, and trajectory — that allows identifying that compensating mechanism. This technique is applied to precipitation over the contiguous United States from both radar-based data products and high-resolution model runs simulating 80 years of business-as-usual warming. In the model study the dominant compensating mechanism is a reduction of storm size. In summer, rainstorms become more intense but smaller; in winter, rainstorm shrinkage still dominates, but storms also become less numerous and shorter duration. These results imply that flood impacts from climate change will be less severe than would be expected from changes in precipitation intensity alone. However, these projected changes are smaller than model–observation biases, implying that the best means of incorporating them into impact assessments is via “data-driven simulations” that apply model-projected changes to observational data. The authors therefore develop a simulation algorithm that statistically describes model changes in precipitation characteristics and adjusts data accordingly, and they show that, especially for summertime precipitation, it outperforms simulation approaches that do not include spatial information.
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Delay-induced rebounds in CO2 emissions and critical time-scales to meet global warming targets
Gabriele Manoli, Gabriel Katul & Marco Marani
Earth's Future, forthcoming
Abstract:
While climate science debates are focused on the attainment of peak anthropogenic CO2 emissions and policy tools to reduce peak temperatures, the human-energy-climate system can hold “rebound" surprises beyond this peak. Following the second industrial revolution, global per-capita CO2 emissions (cc) experienced a punctuated growth of about 100% every 60 years, mainly attributable to technological development and its global spread. A model of the human-energy-climate system capable of reproducing past punctuated dynamics shows that rebounds in global CO2 emissions emerge due to delays intrinsic to the diffusion of innovations. Such intrinsic delays in the adoption and spread of low-carbon emitting technologies, together with projected population growth, upset the warming target set by the Paris Agreement. To avoid rebounds and their negative climate effects, model calculations show that the diffusion of climate-friendly technologies must occur with lags one-order of magnitude shorter (i.e. ~6 years) than the characteristic time-scale of past punctuated growth in cc. Radically new strategies to globally implement technological advances at unprecedented rates are needed if current emission goals are to be achieved.
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Peng Zhang, Junjie Zhang & Minpeng Chen
Journal of Environmental Economics and Management, forthcoming
Abstract:
Climate change shifts the distributions of a set of climatic variables, including temperature, precipitation, humidity, wind speed, sunshine duration, and evaporation. This paper explores the importance of those additional climatic variables other than temperature and precipitation. Using the county-level agricultural data from 1980 to 2010 in China, we find that those additional climatic variables, especially humidity and wind speed, are critical for crop growth. Therefore, omitting those variables is likely to bias the predicted impacts of climate change on crop yields. In particular, omitting humidity tends to overpredict the cost of climate change on crop yields, while ignoring wind speed is likely to underpredict the effect. Our preferred specification indicates that climate change is likely to decrease the yields of rice, wheat, and corn in China by 36.25%, 18.26%, and 45.10%, respectively, by the end of this century.
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Matthew Bartos et al.
Environmental Research Letters, November 2016
Abstract:
Climate change may constrain future electricity supply adequacy by reducing electric transmission capacity and increasing electricity demand. The carrying capacity of electric power cables decreases as ambient air temperatures rise; similarly, during the summer peak period, electricity loads typically increase with hotter air temperatures due to increased air conditioning usage. As atmospheric carbon concentrations increase, higher ambient air temperatures may strain power infrastructure by simultaneously reducing transmission capacity and increasing peak electricity load. We estimate the impacts of rising ambient air temperatures on electric transmission ampacity and peak per-capita electricity load for 121 planning areas in the United States using downscaled global climate model projections. Together, these planning areas account for roughly 80% of current peak summertime load. We estimate climate-attributable capacity reductions to transmission lines by constructing thermal models of representative conductors, then forcing these models with future temperature projections to determine the percent change in rated ampacity. Next, we assess the impact of climate change on electricity load by using historical relationships between ambient temperature and utility-scale summertime peak load to estimate the extent to which climate change will incur additional peak load increases. We find that by mid-century (2040–2060), increases in ambient air temperature may reduce average summertime transmission capacity by 1.9%–5.8% relative to the 1990–2010 reference period. At the same time, peak per-capita summertime loads may rise by 4.2%–15% on average due to increases in ambient air temperature. In the absence of energy efficiency gains, demand-side management programs and transmission infrastructure upgrades, these load increases have the potential to upset current assumptions about future electricity supply adequacy.