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The plant-by-plant retirement needs are not well-understood yet to achieve the rapid transition away from coal use. Here the authors found that operational lifetimes of existing units must be reduced to approximately 35 years to keep warming well below 2 °C or 20 years for 1.5 °C, even if no new capacity comes online.

Abstract Annual carbon dioxide (CO2) emissions from the U.S. power sector decreased 24% from 2000 to 2018, while carbon intensity (CO2 per unit of electricity generated) declined by 34%. These reductions have been attributed in part to a shift from coal to natural gas, as gas‐fired plants emit roughly half the CO2 emissions as coal plants. To date, no analysis has looked at the coal‐to‐gas shift from the perspective of commitment accounting—the cumulative future CO2 emissions expected from power infrastructure. We estimate that between 2000 and 2018, committed emissions in the U.S. power sector decreased 12% (six GtCO2), from 49 to 43 GtCO2, assuming average generator lifetimes and capacity factors. Taking into consideration methane leakage during the life cycle of coal and gas plants, this decrease in committed emissions is further offset (e.g., assuming a 3% leakage rate, there is effectively no reduction at all). Thus, although annual emissions have fallen, cumulative future emissions will not be substantially lower unless existing coal and gas plants operate at significantly lower rates than they have historically. Moreover, our estimates of committed emissions for U.S. coal and gas plants finds steep reductions in plant use and/or early retirements are already needed for the country to meet its targets under the Paris climate agreement—even if no new fossil capacity is added.

Although much research on climate change has focused on its disproportionate effects on the Global South, communities—particularly indigenous populations—within "developed" nations in the Global North can also face significant effects and inadequate assistance. One example is the native village and city of Kivalina in northwest Alaska. Through a case study of Kivalina, this article explores the gaps in U.S. policy for relocating Alaska Natives due to the effects of climate change. There is currently no policy in place—within the United States or internationally—for the resettlement of communities displaced by climate change. And in the United States there is no lead agency in charge of relocating displaced communities, despite several U.S. government reports stating that at least four Alaska Native villages, including Kivalina, must be resettled due to warming Arctic temperatures and erosion. This leaves government agencies in charge of assisting villages like Kivalina, such as the Federal Emergency Management Agency and the Army Corps of Engineers, who are responsible for helping ensure Kivalina's safety but are not empowered to innovate new procedures and holistically address what is an unprecedented problem: climate change. This has left Kivalina in what is termed here an administrative orbit, with residents made to work their way through a patchwork of various government programs and procedures that are time-consuming and often insufficient. In exploring these intra-national inequities, this article examines how a protocol specifically designed for those displaced by climate change, such as "climigration," could be merged with existing government efforts around emergency management to help prevent disasters before they occur, and to protect at-risk communities like Kivalina. Keywords: Disaster management; Alaska: environmentally induced migration; indigenous studies; resilience; displacement; relocation.

Nearly 17% of people in an international survey said they believed the existence of a secret large-scale atmospheric program (SLAP) to be true or partly true. SLAP is commonly referred to as ‘chemtrails’ or ‘covert geoengineering’, and has led to a number of websites purported to show evidence of widespread chemical spraying linked to negative impacts on human health and the environment. To address these claims, we surveyed two groups of experts—atmospheric chemists with expertize in condensation trails and geochemists working on atmospheric deposition of dust and pollution—to scientifically evaluate for the first time the claims of SLAP theorists. Results show that 76 of the 77 scientists (98.7%) that took part in this study said they had not encountered evidence of a SLAP, and that the data cited as evidence could be explained through other factors, including well-understood physics and chemistry associated with aircraft contrails and atmospheric aerosols. Our goal is not to sway those already convinced that there is a secret, large-scale spraying program—who often reject counter-evidence as further proof of their theories—but rather to establish a source of objective science that can inform public discourse.

Increased use of natural gas has been promoted as a means of decarbonizing the US power sector, because of superior generator efficiency and lower CO _2 emissions per unit of electricity than coal. We model the effect of different gas supplies on the US power sector and greenhouse gas (GHG) emissions. Across a range of climate policies, we find that abundant natural gas decreases use of both coal and renewable energy technologies in the future. Without a climate policy, overall electricity use also increases as the gas supply increases. With reduced deployment of lower-carbon renewable energies and increased electricity consumption, the effect of higher gas supplies on GHG emissions is small: cumulative emissions 2013–55 in our high gas supply scenario are 2% less than in our low gas supply scenario, when there are no new climate policies and a methane leakage rate of 1.5% is assumed. Assuming leakage rates of 0 or 3% does not substantially alter this finding. In our results, only climate policies bring about a significant reduction in future CO _2 emissions within the US electricity sector. Our results suggest that without strong limits on GHG emissions or policies that explicitly encourage renewable electricity, abundant natural gas may actually slow the process of decarbonization, primarily by delaying deployment of renewable energy technologies.