The opportunity of agricultural management practices to sequester soil organic carbon (SOC) is recognized as an important strategy for mitigating climate change. However, there is low confidence when it comes to understanding the magnitude of the climate benefit we can expect from SOC sequestration or how best to achieve it. Several issues are often confounded when it comes to the mitigation potential of SOC sequestration and greenhouse gas (GHG) reductions from agriculture, creating confusion and making it difficult to clearly identify the knowns, unknowns and risks to implementing policy and practice recommendations. Here, we identify and explain four major areas of uncertainty: (1) the expected changes in soil carbon or GHG emissions resulting from agricultural management practice changes; (2) the extent to which social, environmental and economic factors constrain mitigation potential; (3) the ability to execute reliable measurement, monitoring, reporting and verification (MMRV) frameworks; and (4) the perception of risk associated with different ways of promoting practice adoption (e.g., voluntary carbon markets fueled by the private sector, pay-for-practice programs funded by public investment). We aim to pinpoint knowledge gaps and areas of disagreement to help right-size expectations and guide effective investment in GHG removals and reductions from agriculture.

AbstractExisting estimates of the climate mitigation potential from cropland carbon sequestration (C‐sequestration) are limited because they tend to assume constant rates of soil organic carbon change over all available cropland area, use relatively coarse land delineations, and often fail to adequately consider the agronomic and socioeconomic dimensions of agricultural land use. This results in an inflated estimate of the C‐sequestration potential. We address this gap by defining a more appropriate land base for cover cropping in the United States for C‐sequestration purposes: stable croplands in annual production systems that can integrate cover cropping without irrigation. Our baseline estimate of this suitable stable cropland area is 32% of current U.S. cropland extent. Even an alternative, less restrictive definition of stability results in a large reduction in area (44% of current U.S. croplands). Focusing cover crop implementation to this constrained land base would increase durability of associated C‐sequestration and limit soil carbon loss from land conversion to qualify for carbon‐specific incentives. Applying spatially‐variable C‐sequestration rates from the literature to our baseline area yields a technical potential of 19.4 Tg CO2e yr−1 annually, about one‐fifth of previous estimates. We also find the cost of realizing about half (10 Tg CO2e yr−1) of this potential could exceed 100 USD Mg CO2e−1, an order of magnitude higher than previously thought. While our economic analyses suggest that financial incentives are necessary for large‐scale adoption of cover cropping in the U.S., they also imply any C‐sequestration realized under such incentives is likely to be additional.

Decarbonizing aviation requires, among other strategies, use of low-carbon liquid fuels, since electrified propulsion of large aircraft is not yet viable. However, commercialization of such ‘sustainable aviation fuels’ is lagging due to uncertainty about their potential. Here, we integrate land-use assessment, hydroclimate and ecosystem modelling and economic optimization in a systems framework to better characterize the biojet-fuel potential of cellulosic feedstocks. Planting 23.2 Mha of marginal agricultural lands in the United States—roughly the land area of Wyoming—with the grass miscanthus satisfies the country’s projected 2040 jet-fuel demand (30 billion gallons yr −1 ) at an average cost of US$4.1 gallon −1 . Centred in the Midwest region, this marginal land base is a mix of croplands (7.2 Mha) and non-croplands (16 Mha), whose conversion into miscanthus delivers productive biomass, regional cooling without soil moisture loss and the lowest system greenhouse gas emissions (at US$50 tCO 2 e −1 carbon price). It is unsustainable to source the same quantity of miscanthus biomass through marginal land conversions in the Plains region. Sustainability considerations generate different land conversion patterns than expected from a purely economic vantage point. Integrated approaches, such as used here, are imperative to realistically evaluate the sustainability of bio-based alternative feedstocks.

This dataset contains the model files and underlying data needed to replicate the analysis in "Sustainable Land Use and Viability of Biojet Fuels."

Land quality influences how farmers allocate croplands in response to market forces. Farmers in the Western Corn Belt (WCB) have historically utilized the highest quality lands for corn cultivation, putting lower quality lands to other uses. This paper questions whether high corn prices influenced expansion of corn cultivation on lower quality lands, and the role played by US biofuel policy in such land use change. Using three decades of data, I estimate that the proportional change in corn acreage to rising corn prices is nearly three times larger in counties with lowest land quality versus those with the highest land quality. This variable response, however, is driven by the changes in cropland use for corn cultivation after 2006, the period following the change in US biofuel policy, and punctuated by two crop price spikes. Marginal agricultural lands and other lower quality lands, such as grasslands used for range or pasture, are therefore prone to conversion into corn cropping disproportionately during high price periods. High price responsiveness of lower quality lands also suggests these lands may cycle in and out of corn cropping opportunistically. This has implications for marginal land availability for bioenergy crops, and poses environmental concerns to the extent lower quality lands are also more environmentally sensitive.

With over half of the world’s population living in cities, there is mounting evidence indicating that investments in urban sustainability can deliver high returns on socioeconomic and environmental fronts. Current scholarship on urban agriculture (UA) reports a wide range of benefits which have been shown to vary with the scale and type of benefit examined. Notably, most city-scale studies do not align benefits of UA with locally meaningful goals. We fill this gap by conducting a city-scale analysis for Phoenix, the fifth largest city in the USA by population, and evaluate these benefits based on their ability to contribute to select desired outcomes specified in Phoenix’s 2050 Sustainability Goals: the elimination of food deserts, provision of green open space, and energy and CO2 emissions savings from buildings. We consider three types of surfaces for UA deployment—undeveloped vacant lots, flat rooftops, and building façades—and find that the existing building stock provides 71% of available UA space in the study area. The estimated total food supply from UA is 183 000 tons per year, providing local produce in all existing food deserts of Phoenix, and meeting 90% of current annual consumption of fresh produce based on national per capita consumption patterns. UA would also add green open space and reduce by 60% the number of block groups underserved by public parks. Rooftop deployment of UA could reduce energy use in buildings and has the potential to displace more than 50 000 tons of CO2 per year. Our work highlights the importance of combining a data-driven framework with local information to address place-based sustainability goals and can be used as a template for city-scale evaluations of UA in alternate settings.

Though urban agriculture (UA), defined here as growing of crops in cities, is increasing in popularity and importance globally, little is known about the aggregate benefits of such natural capital in built‐up areas. Here, we introduce a quantitative framework to assess global aggregate ecosystem services from existing vegetation in cities and an intensive UA adoption scenario based on data‐driven estimates of urban morphology and vacant land. We analyzed global population, urban, meteorological, terrain, and Food and Agriculture Organization (FAO) datasets in Google Earth Engine to derive global scale estimates, aggregated by country, of services provided by UA. We estimate the value of four ecosystem services provided by existing vegetation in urban areas to be on the order of $33 billion annually. We project potential annual food production of 100–180 million tonnes, energy savings ranging from 14 to 15 billion kilowatt hours, nitrogen sequestration between 100,000 and 170,000 tonnes, and avoided storm water runoff between 45 and 57 billion cubic meters annually. In addition, we estimate that food production, nitrogen fixation, energy savings, pollination, climate regulation, soil formation and biological control of pests could be worth as much as $80–160 billion annually in a scenario of intense UA implementation. Our results demonstrate significant country‐to‐country variability in UA‐derived ecosystem services and reduction of food insecurity. These estimates represent the first effort to consistently quantify these incentives globally, and highlight the relative spatial importance of built environments to act as change agents that alleviate mounting concerns associated with global environmental change and unsustainable development.

We provide insights from a five year National Science Foundation project focused on the development of spatially explicit maps of sustainable, regional “hot spots” for the large scale deployment of perennial bioenergy crops (e.g., miscanthus and switchgrass) in the United States. With environmental and economic sustainability as principal constraints, our approach integrates climate, land surface, ecosystem, and economic models. We identify “hot spots” (high suitability areas) where there is evidence of atmospheric cooling without a corresponding deterioration of water resources (e.g., significant soil moisture reduction) and simulate biomass yields on marginal lands that become inputs to our economic optimization model.

The United States (US) and the European Union (EU) are federal systems in which the responsibility for environmental policy-making is divided or shared between the central government and the (member) states. The attribution of decision-making power has important policy implications. This chapter compares the role of central and local authorities in the US and the EU in formulating environmental regulations in three areas: automotive emissions for health related (criteria) pollutants, packaging waste, and global climate change. Automotive emissions are relatively centralised in both political systems. In the cases of packaging waste and global climate change, regulatory policy-making is shared in the EU, but is primarily the responsibility of local governments in the US. Thus, in some important areas, regulatory policy-making is more centralised in the EU. The most important role local governments play in the regulatory process is to help diffuse stringent local standards through more centralised regulations, a dynamic which has become recently become more important in the EU than in the US.

Statistical-Based Scenario Analysis (SBSA) draws from historical observations of key drivers of wholesale prices and simulates their joint effect on revenues to a merchant generation asset via dispatch modeling. Depending on the number of and extent of variation in key drivers and the length of the modeling horizon, as many as 20,000 simulations can be conducted to properly assess the expected earning potential of a merchant asset for a given year. The SBSA approach then integrates the results obtained in these thousands of simulations within a statistical framework, adding the much-desired probability dimension.

Without proper market definition, any diagnostic tests for market power and market pricing safeguards could create more long-term harm than good. FERC needs to supplant its default market definition approach with a prescribed set of market definition techniques, then allow stakeholders to implement these techniques to define the relevant markets in which they participate.

An analysis of two generation assets in a regional market in the Northeast demonstrates how a real options-based valuation framework uncovers and quantifies the value of efficient plant operation in the face of volatile electricity market prices. The analysis shows that a peaking gas-fired facility may be more valuable than a mid-merit coal-fired plant, even though traditional methodologies would favor the coal-fired asset given its lower marginal cost.