US Greenhouse Gas Research Articles

A review of the limitation of legitimate expectation principle in FET Claims in energy regulatory disputes: Can a balance be achieved?

This article explores the intricate interplay between the right of states to regulate in the context of environmental regulations aimed at decarbonization and an investor's right to investment protection, particularly focusing on the Fair and Equitable Treatment (FET) standard in international investment law. With the increasing importance of environmental regulations such as the US Greenhouse Gas Standards and Guidelines for Fossil Fuel-Fired Power Plants, in the transition to cleaner energy sources, the potential economic impacts on investments and resulting investment disputes could be huge, making the balancing of these competing interests a topical issue. The article delves into the prominence of the FET standard in investment protection and its evolution in international investment law. It argues that the limitation on the legitimate expectation element of the FET standard in modern times poses challenges in balancing states' rights to regulate with the protection of foreign investments in decarbonization disputes. The author asserts that recent developments in international investment law, exemplified by treaties like the EU-Canada Comprehensive Economic and Trade Agreement (CETA) and the United States-Mexico-Canada Agreement (USMCA), signal a shift towards prioritizing states' right to regulate over investment protection. By analyzing the limitations on legitimate expectation and investment protection in modern times and the implications for energy investments in the era of decarbonization, the article aims to shed light on the complexities of reconciling the competing interests of states and investors in the evolving landscape of international investment law. Ultimately, this author contends that achieving a balance between these interests is increasingly challenging and may require a reevaluation of the prevailing norms in investment protection.

Hotspots of irrigation-related US greenhouse gas emissions from multiple sources

Hotspots of irrigation-related US greenhouse gas emissions from multiple sources

Comparison of Climate Impact, Clinical Outcome, and Cost-Efficiency of Pediatric Transumbilical Laparoscopic Assisted Appendectomy vs Standard 3-Port Laparoscopic Appendectomy.

Healthcare is responsible for 8.5% of US greenhouse gas emissions. These impacts must be mitigated while maintaining clinical excellence. This study compares clinical outcomes, cost-efficiency, and climate impact of trans-umbilical laparoscopic assisted appendectomy (TULAA) versus 3-port laparoscopic appendectomy (LA). Institutional Review Board approval was obtained. Appendectomies performed between Jan 1, 2020 and December 31, 2022 at a tertiary children's hospital were reviewed. Data abstracted included clinical characteristics, operative approach and findings, supplies and equipment utilized, and complications. For analysis TULAA was combined with cases converted to LA (TULAA+C). To determine a surgical site infection (SSI) increase of ≤ 2.5%, a minimum sample size of 479 patients per group was needed to achieve a power of 80%. A composite supply list for each approach was determined by averaging supplies from cases reviewed. The composite was used to calculate cost-efficiency and climate impact. Life cycle assessment was used to determine the carbon footprint (according to ISO 14067) of supplies and equipment. Analysis was performed on 1,611 appendectomies: 497 LA and 1,114 TULAA+C (932 TULAA, 182 converted). Except for BMI, there were no clinically significant differences between groups. SSI did not increase with TULAA+C (n=15, 1.3%) versus LA (n=6, 1.2%), p=0.81. TULAA+C ($369.21/case) was more cost efficient than LA ($879.30/case) and TULAA+C (24.8 kg CO2e) produced fewer emissions than LA (27.4 kg CO2e). While patient safety and excellent clinical outcomes must remain the top priority in healthcare, the current environmental crisis demands consideration of climate impacts. When clinical non-inferiority can be demonstrated, treatment options with a fewer greenhouse gas emissions should be chosen.

Greenhouse Gas Emissions Due to Unnecessary Antibiotic Prescriptions for Respiratory Diagnoses

Background: Healthcare accounts for 8.5% of total US greenhouse gas emissions (GHGE), with US healthcare the main contributor. Yet little effort has been made to measure healthcare related GHGE. Specifically, GHGE related to unnecessary antibiotic prescriptions is unclear, and to our knowledge, no one has used estimates of GHGE of unnecessary antibiotics as an antibiotic stewardship tool. We aimed to measure GHGE from solid waste associated with unnecessary antibiotic prescriptions for respiratory conditions. Methods: We calculated emissions for an outpatient prescription including the plastic bottle, paper leaflet, and paper bag (photos) based on the weight of each item multiplied by US Environmental Protection Agency (EPA) GHGE factors. Emission factors depend on waste type and treatment method which we assumed to be landfilled. To estimate unnecessary antibiotic prescriptions for respiratory infections, visits from nine University of Utah Health Urgent Care Centers from 2019-2022 were electronically identified and included if they had an ICD-10-CM code for a respiratory diagnosis where antibiotics are not indicated. Waste emissions of the paper and plastic in an individual prescription were then multiplied by the number of unnecessary respiratory antibiotic prescriptions for designated time periods to arrive at total landfilled waste emissions. We used similar methods applied to published 2014 data from CDC to estimate national waste emissions due to unnecessary antibiotic prescriptions for respiratory infections. Finally, we used the EPA’s GHG Equivalencies Calculator to convert emissions into tangible GHGE for providers and patients. Results: A prescription has 32g of paper and 15g of plastic waste. Among 124,461 urgent care visits (Table 1) in 2019-2022, 18,531 (14.9%) received an antibiotic. This equates to 593 kg of paper waste and 278 kg of plastic waste leading to a total landfilled waste emissions of 0.479 MT CO2e/ton. Using the EPA GHG Equivalencies Calculator, this equates to driving an average gasoline-powered car 1,228 miles. There were 14,482,976 unnecessary antibiotic prescriptions (Table 2) in the US for respiratory infections in 2014. Our estimates suggest these prescriptions led to 375.109 CO2e/ton of GHGE, the same as driving 961,610 miles by an average gasoline-powered vehicle. Conclusion: Unnecessary antibiotic prescriptions are associated with substantial GHGE. This estimate demands further evaluation across diagnoses and care delivery sites, and most importantly action. Additionally, the large GHG contribution of unnecessary antibiotics should be used as a stewardship tool to highlight low-value care that is likely contributing to global climate change.

Quantification of the environmental impact of radiotherapy and associated secondary human health effects: a multi-institutional retrospective analysis and simulation

The health-care industry is a substantial contributor to global greenhouse gas emissions, yet the specific environmental impact of radiotherapy, a cornerstone of cancer treatment, remains under-explored. We aimed to quantify the emissions associated with the delivery of radiotherapy in the USA and propose a framework for reducing the environmental impact of oncology care. In this multi-institutional retrospective analysis and simulation study, we conducted a lifecycle assessment of external beam radiotherapy (EBRT) for ten anatomical disease sites, adhering to the International Organization for Standardization's standards ISO 14040 and ISO 14044. We analysed retrospective data from Jan 1, 2017, to Oct 1, 2023, encompassing patient and staff travel, medical supplies, and equipment and building energy use associated with the use of EBRT at four academic institutions in the USA. The primary objective was to measure the environmental impacts across ten categories: greenhouse gases (expressed as kg of carbon dioxide equivalents [CO2e]), ozone depletion, smog formation, acidification, eutrophication, carcinogenic and non-carcinogenic potential, respiratory effects, fossil fuel depletion, and ecotoxicity. Human health effects secondary to these environmental impacts were also estimated as disability-adjusted life years. We also assessed the potential benefits of hypofractionated regimens for breast and genitourinary (ie, prostate and bladder) cancers on US greenhouse gas emissions using an analytic model based on the 2014 US National Cancer Database for fractionation patterns and patient commute distances. We estimated that the mean greenhouse gas emissions associated with a standard 25-fraction EBRT course were 4310 kg CO2e (SD 2910), which corresponded to 0·0035 disability-adjusted life years per treatment course. Transit and building energy usage accounted for 25·73% (1110 kg CO2e) and 73·95% of (3190 kg CO2e) of total greenhouse gas emissions, respectively, whereas supplies contributed only 0·32% (14 kg CO2e). Across the other environmental impact categories, most of the environmental impact also stemmed from patient transit and energy use within facilities, with little environmental impact contributed by supplies used. Hypofractionated treatment simulations suggested a substantial reduction in greenhouse gas emissions-by up to 42% for breast and 77% for genitourinary cancer-and environmental impacts more broadly. This comprehensive lifecycle assessment of EBRT delineates the environmental and secondary health impacts of radiotherapy, and underscores the urgent need for sustainable practices in oncology. The findings serve as a reference for future decarbonisation efforts in cancer care and show the potential environmental benefits of modifying treatment protocols (when clinical equipoise exists). They also highlight strategic opportunities to mitigate the ecological footprint in an era of escalating climate change and increasing cancer prevalence. Mount Zion Health Fund.

Are vehicle lifespan caps an effective and efficient method for reducing US light-duty vehicle fleet GHG emissions?

With light duty vehicles (LDVs) responsible for 17% of annual US greenhouse gas (GHG) emissions, integrating emerging GHG-reducing technologies into the fleet is essential. However, the slow rate of vehicle turnover presents a significant barrier to the market penetration of new technologies, with adoption delayed by the low number of vehicles needing replacement each year. A strategy of accelerated vehicle turnover through a vehicle lifespan cap could potentially mitigate this limit. While older studies reach differing conclusions on their effectiveness, two newer studies that incorporate life cycle assessment find that accelerated turnover strategies can be effective if coupled with high levels of electric vehicle deployment. We seek to determine whether a vehicle lifespan cap strategy can be an effective and efficient (cost-effective) method for reducing US LDV fleet GHG emissions. We augment the capabilities of the Fleet Life Cycle Assessment and Material Flow Estimation (FLAME) fleet life cycle assessment model, integrating vehicle lifespan caps and comprehensive calculations of cost along with sensitivity analysis for electric vehicle survival curves and battery degradation. The augmented FLAME model is used to analyse the impact of vehicle lifespan caps of varying lengths on a suite of scenarios, including a business as usual (BAU) scenario and eight scenarios modelling different technology improvement assumptions. This work confirms that vehicle lifespan caps have limited effectiveness in reducing GHG emissions under a BAU scenario but show potential to meaningfully reduce GHG emissions in a scenario with accelerated deployment of electric vehicles. However, abatement costs are high, exceeding 2020 USD 1000/tCO2eq under baseline assumptions, but falling within the range of current estimates of the social cost of carbon under more optimistic assumptions. Overall, vehicle lifespan caps must be carefully considered as they accelerate both the benefits and costs of new vehicle technologies, and are best positioned as part of a larger integrated strategy for tackling transportation GHG emissions.

Long-term dynamics of aboveground carbon stocks in managed loblolly pine plantations in the southeast United States

Intensively managed pine plantations in the southeastern US could not only meet the increasing demand for traditional wood products and biomass for energy, but also play a critical role in meeting US greenhouse gas emission reduction goals through additional carbon (C) sequestration. Adapting forest management to help mitigate climate change requires better understanding of long-term effects of silvicultural treatments on forest production and C sequestration. With two long-term culture-by-density research experiments for loblolly pine plantations across the southern US, we assessed the impacts of site quality, cultural intensity (operational and intensive), and planting density (741, 1483, 2224, 2965, 3706 and 4448 trees ha−1) on dynamics of aboveground net primary production in C (ANPPC), aboveground live tree C stocks (AGC), and cumulative C lost to tree mortality and other litter production (CLC), and total gross C capture (TGC). Cultural intensity significantly affected ANPPC and AGC before age 15 years, and CLC and TGC during the whole study period; while planting density significantly affected ANPPC before age 15 years, CLC after age 6 years, and AGC and TGC over time. Site quality significantly affected AGC at early and late ages, CLC at mid-rotation, and TGC at early ages. After age 20 years, higher quality sites still resulted in higher AGC than lower quality sites, while higher-planting densities might no longer promote aboveground live tree C stock. Intensive management practices that promote growth along with C accumulation in young stands do not necessarily result in higher C stocks in older stands. There exist a maximum C sequestration rate and a maximum C storage in loblolly pine plantations. Continuing carbon capture in the extended rotation or deferred harvest forests is in no way guaranteed to continuously increase carbon stocks. To develop effective climate-smart forest management recommendations, long-term dynamics of carbon capture, release, and storage, especially in managed forest plantations, need more research.

Hydroxyapatite catalyzed hydrothermal liquefaction transforms food waste from an environmental liability to renewable fuel

SummaryFood waste is an abundant and inexpensive resource for the production of renewable fuels. Biocrude yields obtained from hydrothermal liquefaction (HTL) of food waste can be boosted using hydroxyapatite (HAP) as an inexpensive and abundant catalyst. Combining HAP with an inexpensive homogeneous base increased biocrude yield from 14 ± 1 to 37 ± 3%, resulting in the recovery of 49 ± 2% of the energy contained in the food waste feed. Detailed product analysis revealed the importance of fatty-acid oligomerization during biocrude formation, highlighting the role of acid-base catalysts in promoting condensation reactions. Economic and environmental analysis found that the new technology has the potential to reduce US greenhouse gas emissions by 2.6% while producing renewable diesel with a minimum fuel selling price of $1.06/GGE. HAP can play a role in transforming food waste from a liability to a renewable fuel.

Environmental impact of telehealth use for pediatric surgery

BackgroundThe healthcare sector is responsible for 10% of US greenhouse gas emissions. Telehealth use may decrease healthcare's carbon footprint. Our institution introduced telehealth to support SARS-CoV-2 social distancing. We aimed to evaluate the environmental impact of telehealth rollout. MethodsWe conducted a retrospective cohort study of pediatric patients seen by a surgical or pre anesthesia provider between March 1, 2020 and March 1, 2021. We measured patient-miles saved and CO2 emissions prevented to quantify the environmental impact of telehealth. Miles saved were calculated by geodesic distance between patient home address and our institution. Emissions prevented were calculated assuming 25 miles per gallon fuel efficiency and 19.4 pounds of CO2 produced per gallon of gasoline consumed. Unadjusted Poisson regression was used to assess relationships between patient demographics, geography, and telehealth use. Results60,773 in-person and 10,626 telehealth encounters were included. This represented an 8,755% increase in telehealth use compared to the year prior. Telehealth resulted in 887,006 patient-miles saved and 688,317 fewer pounds of CO2 emitted. Demographics significantly associated with decreased telehealth use included Asian and Black/African American racial identity, Hispanic ethnic identity, and primary language other than English. Further distance from the hospital and higher area deprivation index were associated with increased telehealth use (IRR 1.0006 and 1.0077, respectively). ConclusionIncorporating telehealth into pediatric surgical and pre anesthesia clinics resulted in significant CO2 emission reductions. Expanded telehealth use could mitigate surgical and anesthesia service contributions to climate change. Racial and linguistic minority status were associated with significantly lower rates of telehealth utilization, necessitating additional inquiry into equitable telemedicine use for minoritized populations. Level of evidenceLevel IV

The Tongass National Forest, Southeast Alaska, USA: A Natural Climate Solution of Global Significance

The 6.7 M ha Tongass National Forest in southeast Alaska, USA, supports a world-class salmon fishery, is one of the world’s most intact temperate rainforests, and is recognized for exceptional levels of carbon stored in woody biomass. We quantified biomass and soil organic carbon (C) by land use designation, Inventoried Roadless Areas (IRAs), young and productive old-growth forests (POGs), and 77 priority watersheds. We used published timber harvest volumes (roundwood) to estimate C stock change across five time periods from early historical (1909–1951) through future (2022–2100). Total soil organic and woody biomass C in the Tongass was 2.7 Pg, representing ~20% of the total forest C stock in the entire national forest system, the equivalent of 1.5 times the 2019 US greenhouse gas emissions. IRAs account for just over half the C, with 48% stored in POGs. Nearly 15% of all C is within T77 watersheds, >80% of which overlaps with IRAs, with half of that overlapping with POGs. Young growth accounted for only ~5% of the total C stock. Nearly two centuries of historical and projected logging would release an estimated 69.5 Mt CO2e, equivalent to the cumulative emissions of ~15 million vehicles. Previously logged forests within IRAs should be allowed to recover carbon stock via proforestation. Tongass old growth, IRAs, and priority watersheds deserve stepped-up protection as natural climate solutions.

Lithium Drives EV, Grid Storage as Industry Scrambles To Fill Supply Deficit

What fossil fuel was to the industrial revolution, lithium is to today’s energy transition. Often referred to as the oil of the 21st century, this strategic commodity is essential to the manufacture of batteries, from the 35- to 100-kWh type that power electric vehicles (EVs) to grid-size 100-MW (and larger) battery energy storage systems (BESS) such as those at Tesla’s Gambit Energy Storage Park near Houston, whose power capacity is among the highest in the US. Because lithium-ion batteries charge quickly and last longer due to their higher power density, it is not surprising that as the energy transition picks up the pace, the demand for lithium is rapidly outstripping supply, leaving the industry scrambling to find new sources—whether that means opening new mines or devising new technologies to extract lithium from brines, including brines found in water produced from oil and gas operations. In the EV arena, Deloitte forecast a 29% compound annual growth rate in EV sales over this decade, predicting that EVs will comprise 32% of new car sales by 2030 with China commanding 49% of the market, Europe holding 27%, and the US at 14%. The US Environmental Protection Agency attributes 30% of US greenhouse-gas emissions to transportation, a fact that has prompted the automobile industry to shift into transformational mode to make this decade the tipping point when EVs become mainstream. Catching the Vibe at CES In her keynote at the 2022 Consumer Electronics Show (CES) in Las Vegas, Nevada, in January, General Motors CEO Mary Barra announced that in 2023, GM will launch production of its long-anticipated electric Chevrolet Silverado pickup truck, a move made possible by the company’s $35-billion investment strategy announced last summer to compete with Tesla. GM’s investment plan through 2025 targets, among other things, “on lining” four new, US-based lithium-ion cell production plants with a combined cell production capacity of 140 GWh/year, based on the company’s proprietary Ultium platform. Ultium Cells LLC, a joint venture with LG Energy Solution, announced in late January it would build its third plant in Lansing, Michigan. The JV is currently constructing plants in Lordstown, Ohio, and Spring Hill, Tennessee; the location of the fourth plant has yet to be announced. Back in Las Vegas, Sony grabbed headlines at CES by reaffirming it will open its own automobile unit, Sony Mobility Inc., in the spring of 2022, and Chrysler, a part of the Netherland’s Stellanis group, treated CES visitors to a look at its first EV concept car which is planned to launch in 2025. From that standing start, Stellanis said it expects to convert 70% of its European vehicle sales and 40% of its US sales over to the EV category by 2030.

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Economic solution for low carbon process heat: A horizontal, compact high temperature gas reactor

In 2018, nuclear energy generated 55% of United States’ and one third of the world’s carbon free electricity, making nuclear energy a key tool in efforts to mitigate climate change before 2050. However, the current nuclear technology, light water reactors (LWRs), is limited to 300°C, so it cannot be used to decarbonize industrial process heat which accounts for 12% of US greenhouse gas emissions. High temperature gas reactors (HTGRs) can meet the high temperature demand with carbon free nuclear heat. The estimated cost of HTGRs, such as the Next Generation Nuclear Plant (NGNP), are even higher than state-of-the-art LWRs. In this paper, we expanded our nuclear cost estimating tool to include HTGRs and find that the NGNP overnight capital costs were 32% higher than an advanced LWR per unit capacity. The higher cost will naturally result in larger risk to cost overrun as recently experienced by larger LWRs in western nations. With a design-to-build mindset to minimize cost and construction risk, we introduce the horizontal, compact HTGR (HC-HTGR). The reactor core and steam generator are mounted horizontally on rails and in-line with one another, decreasing the size of the reactor building relative to the power capacity four times when compared to traditional HTGRs. The HC-HTGR reduced overnight civil structure costs by 42%, indirect costs by 38%, and total capital costs by 20% from NGNP. We discussed the required engineering of new systems for the HC-HTGR including vessel supports, the reactor cavity cooling system, and steam generator design. Finally, we estimated the fuel and operations costs of the HC-HTGR, and a survey of low-carbon industrial process heat technology showed the HC-HTGR can deliver a highly competitive levelized cost of heat in the range of $6.13–12.48/GJ.

The power and promise of improved climate data infrastructure

The announcement by the Biden Administration to reengage the Paris climate process and lower US greenhouse gas (GHG) emissions 50% by the end of this decade is an essential development in the global effort to avoid the worst impacts of climate change (1). However, promises to reduce US GHG emissions are not new and have thus far delivered little real and sustainable emissions reductions (2). The result? Climate change continues unabated, and we forgo the associated jobs and technological innovation that will fuel economic growth in climate friendly businesses. It must be different this time—pledges must lead to practical policy and quickly. To mitigate greenhouse gas emissions, we need accurate and transparent emissions data infrastructure that maps when emissions are happening and where they’re coming from. Image credit: Shutterstock/Tatiana Grozetskaya. To meet the US emission pledge, practical policies will need to reach broadly across the US economy and mobilize new technologies, behavioral change, and private capital. Regardless of policy specifics, actionable GHG reduction policies will fundamentally rest on critical climate data infrastructure that comprehensively and reliably quantifies and tracks GHG emissions in the United States from the local to the national scale. Ideally, all citizens should be able to see a daily map of detailed emissions across the US landscape, much like viewing daily weather. In other words, we need a “US Greenhouse Gas Information Service.” Such a service would provide local emission context to our daily lives and is essential to determine whether emission reduction claims are real, if they’re targeting the best opportunities from neighborhoods to the nation, and whether they’re establishing the trust necessary to mobilize and sustain reduction investment. Right now, however, US climate data collection and dissemination efforts are falling short. Measurement and tracking of GHG emissions reflect a collection of ad hoc mandates and … [↵][1]1To whom correspondence may be addressed. Email: kevin.gurney{at}nau.edu. [1]: #xref-corresp-1-1

Quantifying Methane and Ozone Precursor Emissions from Oil and Gas Production Regions across the Contiguous US.

We present an updated fuel-based oil and gas (FOG) inventory with estimates of nitrogen oxide (NOx) emissions from oil and natural gas production in the contiguous US (CONUS). We compare the FOG inventory with aircraft-derived ("top-down") emissions for NOx over footprints that account for ∼25% of US oil and natural gas production. Across CONUS, we find that the bottom-up FOG inventory combined with other anthropogenic emissions is on average within ∼10% of top-down aircraft-derived NOx emissions. We also find good agreement in the trends of NOx from drilling- and production-phase activities, as inferred by satellites and in the bottom-up inventory. Leveraging tracer-tracer relationships derived from aircraft observations, methane (CH4) and non-methane volatile organic compound (NMVOC) emissions have been added to the inventory. Our total CONUS emission estimates for 2015 of oil and natural gas are 0.45 ± 0.14 Tg NOx/yr, 15.2 ± 3.0 Tg CH4/yr, and 5.7 ± 1.7 Tg NMVOC/yr. Compared to the US National Emissions Inventory and Greenhouse Gas Inventory, FOG NOx emissions are ∼40% lower, while inferred CH4 and NMVOC emissions are up to a factor of ∼2 higher. This suggests that NMVOC/NOx emissions from oil and gas basins are ∼3 times higher than current estimates and will likely affect how air quality models represent ozone formation downwind of oil and gas fields.

Synthesis of FeCo-N-OLC Catalyst for Oxygen Reduction Reaction

The world's main source of energy is fossil fuels, but fossil fuels are finite resources and can also irreparably harm the environment. According to the United States Energy Information Administration, the burning of fossil fuels was responsible for 76 percent of the US greenhouse gas emissions. Fossil fuels not only pollute the environment, but also affect human health. My research focuses on making a catalyst that is economical, efficient and above all friendly to the environment. The oxygen reduction reaction (ORR) is an important reaction for energy conversion systems, such as fuel cells. The fuel cells generate electricity directly by electrochemically reducing oxygen and oxidizing fuel in water as the only by-product. Onion-like carbon (OLC) are used as a catalytic support for fuel cell applications due to their high conductivity and high surface-to-volume ratio. The combination of carbon compounds with conductive polymers results in new materials and devices with possible practical applications. In recent decades, several studies have been conducted on nitrogen doped structures in carbon materials for the ORR. In my research we use nanodiamonds (NDs) to dope them with the polymerization of the aniline monomer. Then, through a pyrolysis process, we convert the ND/PANI particles into N-OLC. These particles are then polymerized using the aniline and pyrrole monomers to dope the OLCs with nitrogen. These particles are characterized using the following techniques, Raman, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and X-ray Diffraction (XRD). Then the synthesis is carried out with the non-precious metals. The non-precious metals that we use are iron and cobalt. ORR experiments were performed with the FeCo-N-OLC particles. In future work we will characterize these samples using synchrotron techniques.

The environmental footprint of data centers in the United States

Much of the world’s data are stored, managed, and distributed by data centers. Data centers require a tremendous amount of energy to operate, accounting for around 1.8% of electricity use in the United States. Large amounts of water are also required to operate data centers, both directly for liquid cooling and indirectly to produce electricity. For the first time, we calculate spatially-detailed carbon and water footprints of data centers operating within the United States, which is home to around one-quarter of all data center servers globally. Our bottom-up approach reveals one-fifth of data center servers direct water footprint comes from moderately to highly water stressed watersheds, while nearly half of servers are fully or partially powered by power plants located within water stressed regions. Approximately 0.5% of total US greenhouse gas emissions are attributed to data centers. We investigate tradeoffs and synergies between data center’s water and energy utilization by strategically locating data centers in areas of the country that will minimize one or more environmental footprints. Our study quantifies the environmental implications behind our data creation and storage and shows a path to decrease the environmental footprint of our increasing digital footprint.

Re-designing America's suburbs for the age of climate change and pandemics.

The USA is the leading emitter of greenhouse gases among the developed countries, in part because it is the only developed country with more of its population in suburbs than in cities. Cities produce less greenhouse gas emissions per capita than suburbs. Meanwhile, the US and the world have been wrestling with the public health emergency of the COVID-19 pandemic. But as US cities recover from the pandemic, they are unlikely to add more population than their suburbs because of changes in favor of working from home, online shopping, and the search for more affordable housing and green space, as well as concerns about population density and contagious diseases. So, the challenge is how to design and redevelop suburbs to make them more environmentally, socially, and economically sustainable to address both climate change and the threat of future pandemics. A sustainable suburb scenario offers an alternative to the sprawling development, separation of land uses and income classes, and automobile dependence that characterizes the typical American suburban landscape. This essay reviews the literature on re-designing suburbs and describes and evaluates both a business-as-usual suburb scenario and a sustainable suburb scenario. Though challenges exist, sustainable suburbs will be needed in order to reduce US greenhouse gas emissions, to achieve greater resilience in adapting to the effects of climate change, and to guard against future pandemics while providing economic opportunities and greater equity over the long run.

2010–2015 North American methane emissions, sectoral contributions, and trends: a high-resolution inversion of GOSAT observations of atmospheric methane

Abstract. We use 2010–2015 Greenhouse Gases Observing Satellite (GOSAT) observations of atmospheric methane columns over North America in a high-resolution inversion of methane emissions, including contributions from different sectors and their trends over the period. The inversion involves an analytical solution to the Bayesian optimization problem for a Gaussian mixture model (GMM) of the emission field with up to 0.5∘×0.625∘ resolution in concentrated source regions. The analytical solution provides a closed-form characterization of the information content from the inversion and facilitates the construction of a large ensemble of solutions exploring the effect of different uncertainties and assumptions in the inverse analysis. Prior estimates for the inversion include a gridded version of the Environmental Protection Agency (EPA) Inventory of US Greenhouse Gas Emissions and Sinks (GHGI) and the WetCHARTs model ensemble for wetlands. Our best estimate for mean 2010–2015 US anthropogenic emissions is 30.6 (range: 29.4–31.3) Tg a−1, slightly higher than the gridded EPA inventory (28.7 (26.4–36.2) Tg a−1). The main discrepancy is for the oil and gas production sectors, where we find higher emissions than the GHGI by 35 % and 22 %, respectively. The most recent version of the EPA GHGI revises downward its estimate of emissions from oil production, and we find that these are lower than our estimate by a factor of 2. Our best estimate of US wetland emissions is 10.2 (5.6–11.1) Tg a−1, on the low end of the prior WetCHARTs inventory uncertainty range (14.2 (3.3–32.4) Tg a−1), which calls for better understanding of these emissions. We find an increasing trend in US anthropogenic emissions over 2010–2015 of 0.4 % a−1, lower than previous GOSAT-based estimates but opposite to the decrease reported by the EPA GHGI. Most of this increase appears driven by unconventional oil and gas production in the eastern US. We also find that oil and gas production emissions in Mexico are higher than in the nationally reported inventory, though there is evidence for a 2010–2015 decrease in emissions from offshore oil production.

Drivers of change in US residential energy consumption and greenhouse gas emissions, 1990–2015

Annual greenhouse gas (GHG) emissions from residential energy use in the United States peaked in 2005 at 1.26 Gt CO2-eq yr−1, and have since decreased at an average annual rate of 2% yr−1 to 0.96 Gt CO2-eq yr−1 in 2019. In this article we decompose changes in US residential energy supply and GHG emissions over the period 1990–2015 into relevant drivers for four end-use categories. The chosen drivers encompass changing demographics, housing characteristics, energy end-use intensities, and generation efficiency and GHG intensity of electricity. Reductions in household size, growth in heated floor area per house, and increased access to space cooling are the main drivers of increases in energy and GHG emissions after population growth. Growing shares of newer homes, and reductions in intensity of energy use per capita, household, or floor area have produced moderate primary energy and GHG emission reductions, but improved generation efficiency and decarbonization of electricity supply have brought about far bigger primary energy and GHG emission reductions. Continued decline of residential emissions from electrification of residential energy and decarbonization of electricity supply can be expected, but not fast enough to limit climate change to 1.5 °C warming. US residential final energy demand will therefore need to decline in absolute terms to meet such a target. However, without changes in the age distribution, type mix, or average size of housing, improvements in energy efficiency are unlikely to outweigh growth in the number of households from population growth and further household size reductions.