We use daily, county-level gas consumption data and interpretable machine learning models to assess spatial patterns in natural gas consumption of households as a function of outdoor air temperature, as well as factors such as household income, employment rates, the size, age and type of homes, employment rates, and a range of other characteristics.

Edible molecules can be directly synthesized without agricultural feedstocks, saving land, water and GHG emissions. Dietary fats made from natural gas feedstock and average U.S. electricity would emit ~0.8 gCO₂-eq/kcal (and 0 if using atmospheric carbon and renewable electricity) compared to 1-3 gCO₂-eq/kcal from agricultural fat production.

Using a newly developed database of iron and steel plants worldwide, we identify the most cost-effective regional priorities for decarbonization. Our database will be regularly updated and improved to support future plant-by-plant strategic mitigation planning for global net-zero steelmaking.

We use machine learning to quantify the relationship of temperature and wildfires that grow by >10,000 acres/day in California, finding that human-caused warming has increased the frequency of such wildfire growth by ~25% relative to the preindustrial era, which will further increase to ~59% by 2100 even if warming is kept low (i.e. <2°C).

Through a combination of emission, atmospheric, and health models, we find that the co-deployment of both air pollution and climate policies could help to avoid more than 2 million premature deaths per year by 2060. Keys to success include upgrading industrial facilities to ultra-low emissions, stricter emission standards on vehicles, and phasing out fossil fuels.

Impact-based drought monitoring links drought to physical or societal impacts such as crop yield, food availability, energy generation or unemployment, to the benefit multiple stakeholders involved in drought planning, and risk and response management, with clear benefits for food and water security.

We model reductions in food loss and waste to show that there could be substantial rebound effects--price decreases and consumption increases—-that would offset some of the benefits of avoided loss and waste.

Using a new model of global seaweed growth, we estimate that harvesting 1 Gt/year of seaweed carbon would require farming over 1 million km2 of the most productive exclusive economic zones, located in the equatorial Pacific. But 2 Gt/year would require more than 3 million km2--carbon harvest efficiency drops off quickly beyond the most productive waters.

Using carbon monoxide retrievals and an atmospheric inversion model, we show that CO₂ emissions from boreal wildfires in 2021 shattered records: 1.8 GtCO₂. If such high levels of fire emissions become normal, stabilizing climate will be even more difficult than we expected.

We analyze sectoral and country-based daily natural gas supply–storage–consumption to estimate the scale of the gap if Russian gas imports were to stop and potential short-term solutions to fill the gap. Our datasets could be important to gas/energy consumption and market modeling, carbon emission and climate change research, and policy decision-making.

We show that radiative effects of smoke aerosols can modify near-surface wind, air dryness, and rainfall, and hence worsen air pollution by enhancing fire emissions and weakening dispersion. The positive feedback created by interactions of wildfires, smoke, and weather substantially increases exposure to air pollution.

Using near-real-time daily national CO2 emissions estimates from the Carbon Monitor and a multi-source spatial activity and satellite NO2 data, we estimate daily CO2 emissions at 0.1° × 0.1° resolution from industry, power, residential consumption, ground transportation, international aviation, domestic aviation, and international shipping.

We assess nine possible pathways to achieve net-zero emissions from aviation, including changes and trade-offs in demand, energy efficiency, propulsion systems, and alternative fuels for both passenger and freight transport, as well as atmospheric carbon removal to offset non-CO₂ radiative forcing.

We estimate how many tons of steel, copper, silver, rare earth metals, and other materials will be needed to build power generation facilities across a wide range of scenarios. Although wind and solar energy require lots of such materials and current production will need to increase, availability of metals and materials will not constrain the projected expansion.

Global modeling shows that potential climate benefits of farming seaweed are large but sensitive to uncertain yields and competition with phytoplankton. We also find that carbon removal by sinking seaweed is much costlier than avoiding emissions by substituting seaweed for land-based crops.

We investigate global connections to agricultural risks from changing snowmelt via international trade, showing how local impacts to food and water systems are transferred internationally important implications for countries' food security under climate change.

Ultra-high-resolution modeling of Los Angeles flood risks reveals risks that are vastly larger than suggested by federally-defined floodplains and with both racial and socio-economic inequalities in exposure. Our approach points to opportunities for assessing and equitably reducing flood risks in densely-populated urban areas.

We review existing methods of drought prediction, discuss major research gaps and opportunities for improvement. In particular, we show that there are opportunities to leverage artificial intelligence and machine learning advances to develop bottom-up drought prediction models—i.e. starting from the reality (here, observed events) and searching for model(s) and driver(s) that work.

We project CO2 emissions in 59 countries where emissions grew faster 2010–2018 than the global average (excluding China and India) under a range of longer-term energy scenarios. Future emissions from these countries could jeopardize international climate goals; mitigation efforts cannot neglect these emerging emitters.

We quantify the magnitude and distribution of health co-benefits of different decarbonization scenarios in California. Those that prioritize building electrification over truck electrification lead to greater overall health benefits, but truck electrification benefits vulnerable communities more effectively.

Hourly, plant-level emissions of PM, SO₂,NO_X between 2014–2018 have decreased as the result of Chinese regulations, but CO₂ emissions have not. Further analysis shows where further changes in plant operation and technology improvements will occur to meet ultralow emission standards and carbon neutrality target.

We estimates day-to-day changes in fossil-fuel CO₂ emissions from human activities in 2020, revealing a complex balance of influences from seasonality, working days, weather and the COVID-19 pandemic. The extraordinary fall in emissions during 2020 is similar in magnitude to the sustained annual emissions reductions necessary to limit global warming at 1.5 °C.

Annually, 27% of land-use emissions are related to agricultural products consumed in a different region from where they were produced. The largest transfers are land-use change emissions from Brazil, Indonesia, and Argentina embodied in products consumed in Europe, the US, and China. Our results highlght the importance of trade in stopping deforestation and making food systems more sustainable.

In support of the global stocktake of the Paris Agreement on climate change, we present a comprehensive framework to compare carbon dioxide (CO₂) fluxes from an ensemble of atmospheric inversions with national greenhouse gas inventories (NGHGIs) submitted by countries to the United Nations Framework Convention on Climate Change (UNFCCC).

Global CO2 emissions in 2021 were only 1% less than the record levels of 2019, driven by increases in power- and industry-related emissions from China and India and a return of the carbon intensity of electricity to pre-pandemic levels. Is this resumed growth in fossil energy, or a final fleeting surge before a long decline?

It is possible — and crucial — to green the building blocks of the modern world. We highlight nine priorities for research and action. Steel manufacturing processes need a rethink; cement’s biggest gains will require carbon capture and storage (CCS). Together, these steps could take steel close to being carbon neutral and cement to becoming a carbon sink.

Following record-level declines in 2020, near-real-time data indicate that global CO₂ emissions rebounded by 4.8% in 2021, reaching 34.9 GtCO₂. These 2021 emissions consumed 8.7% of the remaining carbon budget for limiting anthropogenic warming to 1.5 °C, which if current trajectories continue, might be used up in 9.5 years at 67% likelihood.

Fossil CO₂ emissions in 2021 grew an estimated 4.2% (3.5%–4.8%) to 36.2 billion metric tons compared with 2020, pushing global emissions back close to 2019 levels (36.7 Gt CO₂).

Using a range of detailed energy-emissions scenarios and chemical transport/epidemiological models, we show that without ambitious climate mitigation (i.e. changes in underlying energy sources), PM2.5-related deaths in China may increase in the future--regardless of clean-air policies and air quality improvements.

We review the importance of considering integrated systems and systems of systems as we decarbonize our the economy. Further, we review and summarize the innovation challenges of particular sectoral interfaces, and highlight advances in materials and processes that will be critical to successful achievement of economy-wide, low-carbon energy systems.

Analyzing daily changes in Europe's natural gas use during the first half of year 2020, we find that climate variations played a larger role than COVID-19 induced stay-home orders in natural gas consumption.

Modeling individual electricity-generating units worldwide across a range of climate–energy policy scenarios, we show that air pollution deaths are not an automatic and fixed co-benefit of climate mitigation. Rather, pollution controls and strategic retirements of power plants may ultimately determine the extent to which health co-benefits are realized.

We show that the impact of short-term regional changes in fossil fuel emissions on CO₂ concentrations during the early months of the COVID-19 pandemic was observable from space. Column CO₂ over many of the world’s largest emitting regions was 0.14 to 0.62 ppm less than expected in a pandemic-free scenario.

We present the first spatially-explicit dataset of daily, sector-specific, and global CO₂ emissions from fossil fuel and cement production with a spatial-resolution of 0.1° by 0.1°. The product integrates daily and near-real-time emissions estimates from the Carbon Monitor with spatial patterns from the GID, EDGAR and spatiotemporal patters of satellite NO₂ retrievals.

Analyzing 39 years of hourly weather data across 42 countries, we show that, to a first approximation, the variability of solar and wind resources in a country largely determine how much "overbuilding," long-duration storage, long-distance transmission, and/or firm generation back-up will be necessary.

We systematically examine energy systems in 177 integrated assessment model scenarios when the world reaches net-zero emissions. We find, e.g., that renewable energy sources on average account for 60% of primary energy at net-zero, with electricity roughly half of final energy, and residual and negative emissions are uneven among world regions.

Some methane emissions may be extremely difficult to avoid, such that technologies for atmospheric methane removal or oxidation may be needed to stabilize Earth's climate at a given mean temperature. We outline some considerations for a research agenda on negative methane emissions—including both removal or atmospheric methane oxidation.

We provide a perspective on the current understanding of net-zero emissions systems and guidance for policy- and decision-makers on key characteristics of these systems. We highlight robust insights emerging about net-zero systems and unknowns about technologies, markets, policies, and sociotechnical systems.

We use index decomposition analysis and chemical transport modelling to quantify the importance of eight different factors on PM_2.5-related deaths in China 2002-2017. Emission control technologies avoided 0.87 million deaths over the period, while energy-climate policies and changes in economic structure together avoided 0.39 million deaths. Future gains will mostly depend upon further changes in structure and energy.

We compare total emissions reductions of flow battery storage in a future California grid (>80% wind and solar) using a combination of dispatch modeling and life cycle analysis. We find that marginal benefits of such storage reach zero at less than 3 days of mean renewable generation, and in some cases as little as 1 day of mean generation.

Review and analysis of global greenhouse gas emissions by sector (energy, industry, buildings, transport and agriculture, forestry and other land uses) and region 1990-2018. The prominent global pattern is a continuation of underlying drivers with few signs of emerging limits to demand, nor of a deep shift towards the delivery of low and zero carbon services across sectors.

China produces roughly half of the world's steel. We analyze smokestack measurements of pollutant and CO2 concentrations from most of China's steel plants and show that emissions of SO₂ and NO_x have decreased by >40% since the adoption of new standards in 2015 and could fall by a further 37-58% if the latest ultralow emissions standards are met.

Analyzing global surface temperature anomalies at 1 km resolution, we find that daytime summer temps in urban areas are 3.21 °C warmer than surrounding rural areas on average, but that changing vegetation and albedo could substantially mitigate the effect. Explore the new dataset.

An overview of the main decarbonization options for cement production, bounding their relative importance and value. Deployment of CCS is key but we show that cement could potentially produce significant quantities of “negative emissions” if municipal solid waste is used as a fuel--for which there will be significantly less demand than clean biomass.

We update estimates of carbonation by cement materials worldwide, finding uptake of 0.89 Gt CO₂ yr^-1 (95 % CI: 0.76–1.06 Gt CO₂) in 2019, and cumulative uptake 1930-2019 equal to roughly 55% of process emissions over the same period.

We show that China will struggle to acheive its air quality goals after 2030 without also pursuing ambitious climate mitigation. Rather than a co-benefit, hoped-for reductions in air pollution will largely depend on decarbonization.

We estimate the value of irrigation water in California and compare the agricultural costs of water shortages under both the existing water rights framework and an alternate system that allows for trading of water and could reduce the costs of water shortages by $390 million per year (4.6% of California's net agricultural revenue).

In the post-COVID-19 era, global emissions reductions of 1–2 GtCO₂ per year are needed to keep warming well below 2°C. Temporary decreases in emissions due to COVID-19 restrictions will not result in long-term reductions unless recovery sees large-scale deployment of renewable energy and disinvestment in fossil-fuel infrastructure worldwide.

We estimate country-, process-, GHG- and product-specific land-use emissions 1961-2017. Total emissions have increased to 14.6 GtCO_2-eq in 2017 (~25% of anthropogenic GHG emissions). Our results may help prioritize mitigation efforts, but suggest drastic reductions in emissions will require similarly drastic changes in agricultural production and/or practices.

The costs of fires are much greater and more dispersed than the destroyed infrastructure. Of the $149 billion in losses due to 2018 California wildfires, only 19% were related to destroyed infrastructure. 22% of costs are health damages related to air pollution and 59% were indirect damages due to the broader disruption of economic supply chains.

We use satellite observations of NO₂ to deduce 10-day moving averages of NO_x and CO₂ emissions over China, differentiating emissions by sector and province. Between January and April 2020, China’s CO₂ emissions fell by 11.5% compared to the same period in 2019, but emissions have since rebounded to pre-pandemic levels.

We study the changes in human carbon emissions using spaceborne observations from NASA's second Orbiting Carbon Observatory (OCO‐2) from February to May 2020 and discuss needs for future carbon‐dioxide observing systems that will monitor such emissions.

The data and methods of our research collaborative, Carbon Monitor. Using hourly to daily electrical power generation data of 31 countries, monthly production data and production indices of industry processes of 62 countries/regions, and daily mobility data and mobility indices for the ground transportation of 416 cities, we estimate daily national emissions worldwide.

African CO₂ emissions were just 4% of global fossil fuel emissions in 2017, but have grown by nearrly 5% per year for nearly two decades. If the continent-wide such growth persists, by 2030 the continent's emissions will have risen by ~30% (to 1.6 Gt CO2), a sizeable quantity very much at odds with international climate targets.

We present daily estimates of country-level CO₂ emissions for different sectors based on near-real-time activity data. This is a new dataset developed during the COVID pandemic that substantially advances the frontier of emissions monitoring. It also represents the genesis of a new international research collaborative, Carbon Monitor.

China’s success in improving air quality by cutting polluting emissions may have a negative knock-on effect on climate change overall. We estimate that Chinese policies implemented between 2006 and 2017 has had tremendous health benefits, but will also "unmask" >0.1 °C warming as well as precipitation changes over the northern hemisphere.

Using an idealized electricity system model and historical weather data, we show that cost reductions in firm generation technologies uniformly result in greater penetration of the firm technologies and less penetration of variable renewables, with limited effects on system costs when firm technologies have high fixed costs.

In least-cost systems that rely on wind and solar only, energy storage fills hourly gaps when storage costs are high (>$100/kWh) but does not fill seasonal gaps until storage is nearly free. For high reliability with minimal curtailment in such systems, energy storage costs need to decrease several hundred-fold from current costs (to ~$1/kWh).

About 30% of all U.S. counties receive 90% of their air pollution health damages from emissions in other counties, and damage-importing counties tend to have lower median incomes. Our results support continued state and federal cooperation to meet air quality standards and reduce the damages caused by PM_2.5 from transported air pollution.

Although U.S. annual CO₂ emissions fell by 24% between 2000 and 2018, committed emissions of the U.S. power sector decreased only 12% over the period. This is due to large changes in the age and composition of the U.S. generating fleet: old coal plants were replaced by brand new gas ones that can be expected to operrate for 30-40 years.

Using 39 years of hourly U.S. weather data and a macro-scale energy model, we show that currently available long-duration storage technologies like power-to-gas-to-power lower the cost of solar-wind-battery electricity systems.

We show that direct radiative effects of short-lived aerosols may substantially offset the "climate penalty" that prior studies have shown (i.e. that future climate change is likely to worsen air quality and thereby human health in most regions by favoring weather conditions that increase concentrations of air pollution).

In the modern era of global observing networks, pervasive sensing and tracking of human mobility and behaviour, unprecedented COVID-19 disruptions are an opportunity for understanding the Earth System. We hypothesize Earth System responses along cascades of energy, emissions, climate and air quality, and poverty, globalization, food and biodiversity.

By combining ground- and satellite-based observations with chemical transport modeling, we show why haze pollution increased over parts of China during the COVID-19 lockdown. Decreases in transportation NO_x emissions increased ozone and nighttime NO₃ radical formation, and these increases in atmospheric oxidizing capacity in turn facilitated the formation of secondary particulate matter.

We show that stricter, shorter COVID lockdowns reduce overall losses relative to weaker but longer ones. But even a lengthy period of moderate restrictions is economically preferable to lifting all restrictions if it can avoid the need for another round of strict lockdowns. Regardless, losses propagate via global supply chains; best case responses are globally coordinated.

We show that ambitious climate mitigation scenarios entail drastic, and perhaps un-appreciated, changes in the operating and/or retirement schedules of power infrastructure. For example, in 1.5 or 2°C scenarios, the median age of global coal plants at retirement is <10 years.

Former postdoc Sadegh and team present an interactive analysis toolbox, Nexus of Food, Energy, and Water (NeFEW), that synthesizes global data for modeling and analysis of resources and their interdependencies at country-level and for user-specified categories and quantities:
Download NeFEW toolbox

By analyzing integrated health and climate benefits, we show that reducing U.S. CO₂ emissions by 30% could yield $21−68 billion in annual health benefits depending on the locations of coal plants that are replaced with wind, solar, or natural gas.

Future changes in the fraction of precipitation falling as snow and the timing of snowmelt jeopardize food production in basins where irrigated agriculture relies heavily on snowmelt runoff. We assess the most at-risk basins and crops worldwide, where adaptation of water management and agricultural systems may be especially critical in a changing climate.

By analyzing 35 years of temperature, ozone levels, and crop yield data, we estimate the impacts of warming and ozone pollution on perennial fruits and nuts in California. These crops, which represent ~38% of the state's agriculture by value, suffer damages of about $1 billion per year due to ozone in recent years. With 2°C of warming, almond yields will drop by ~10%.

We show that shifts in crop areas worldwide 1973-2012 have substantially avoided increases in growing season temperatures that would have otherwise have been experienced by rainfed maize, wheat, rice and soybean. This suggests that crop "migration" has thus far been an important adaptive mechansim.

Despite their large negative impacts on human health, anthropogenic aerosols have masked some of the global warming induced by GHGs. Our simulations show that--although the net effects of this cooling on the global economy are small--they benefit developing tropical economies while harming developed high-latitude economies, thereby diminishing national inequality.

Analyzing a high resolution dataset of global land use/cover, we find that urban expansion has reduced terrestrial net primary production worldwide between 2000-2010, offsetting 30% of climate-driven increases over the same period. Our results highlight the carbon cycle impacts of urban expansion, and the need to enhance natural carbon sinks and increase agricultural productivity

Of more than 1 million annual deaths in China due to air pollution, about 44% can be attributed to consumption activities of Chinese households. We show that the more deaths are related rural than urban consumers, largely due to direct emissions from solid fuel combustion in rural China. Our results may inform more effective and equitable clean air policies in China.

Future climate change may exacerbate the impacts of Chinese air pollution by increasing the frequency and duration of weather conditions that enhance pollution exposure. Under a scenario that avoids 3°C of mean warming but holds emissions constant, we estimate 12,100 and 8,900 more Chinese will die each year from PM2.5 and ozone exposure, respectively.

If operated as historically, existing fossil energy infrastructure will emit >650 Gt of CO₂, well over the most recent 1.5°C carbon budgets and 2/3 of the remaining 2°C budget. There is thus little or no room for new fossil infrastructure under the targets; rather existing infrastructure must be retired early.

Some water uses are more or less flexible than others due to larger curtailment costs or social impacts. We construct and present a new water stress index that integrates water scarcity, flexibility, and variability, and use it to evaluate the most-stressed basins worldwide.

New research from the USGS shows that fossil fuels produced on federal lands accounted for over 20% of U.S. emissions in recent years. Yet there are numerous ways in which federal lands might instead lead decarbonization.

Climate change impacts on the biosphere tend to increase carbon emissions (a postive feedback). Meanwhile, the impacts on human activities may reduce carbon emissions by a similar amount (a negative feedback). Bad news for both nature and humans, but the feedbacks may largely offset each other.

Concurrent drought and heat extremes in the future may cause substantial decreases in barley yields, leading to dramatic regional decreases in beer consumption (e.g., -32%) and increases in beer prices (e.g., +193%) in some years.

Despite increasing access to electricity, the reliability of electricity remains poor in many developing countries. We explain new research showing the magnitude of economic and environmental costs of electricity outages in sub-Saharan Africa.

In the first study to use a fully-coupled Earth system model to look at the future climatic effects of trans-Arctic shipping, we find that clouds formed in response to shipping emissions may offset ~1°C of the overall warming trend in the Arctic by the end of the century.

China's emissions decreased between 2013-2016. Our analysis shows the decline was largely due to changes in industrial structure and a decline in the share of coal for energy production. Decreases may persist if nascent industrial and energy system transitions continue.

Although there are many options for reducing energy-related CO₂ emissions, some energy services entail emissions that are much more difficult to eliminate. We review technological opportunities and barriers for eliminating and/or managing difficult-to-decarbonize services, and critical areas for further research, development, demonstration and deployment.

We present new, city-level estimates of CO₂ emissions for 182 Chinese cities, decomposed into 17 different fossil fuels, 46 socioeconomic sectors, and 7 industrial processes, and examine three scenarios of technological progress to show that large reductions (up to 31%) are possible by updating a disproportionately small fraction of existing infrastructure.

"South-South" trade among developing countries is increasing, and helping to reduce China’s emissions by shifting energy-intensive production to less developed regions. But this may make climate mitigation more challenging; emissions are spread among more and less-developed countries.

Differences in Chinese cities’ carbon intensity are largely due to disparities in economic structure that can in turn be traced to past investment-led growth. Related carbon lock-in may hinder China’s efforts to reduce emissions from activities in urban areas.

Analysts and markets have struggled to predict a number of phenomena in U.S. energy markets over the last decade or so, such as the rise of natural gas. I explain new research that shows this may be a result of the industry--and consequently the market--becoming increasingly volatile.

The Paris Agreement highlights the need for local climate leadership. The University Of California’s approach to deep decarbonization offers lessons in efficiency, alternative fuels and electrification. Bending the emissions curve globally requires efforts that blend academic insights with practical solutions.

Analysis of hourly weather data shows that meeting >80% of U.S. electricity demand with only solar and wind would require days' or weeks' worth of energy storage--even assuming a continental-scale transmission grid. Today this would be very costly.

We assess fuel- and region-specific opportunities for reducing undesirable air pollutant emissions using a newly developed emission dataset at the level of individual generating units. Retiring or installing emission control technologies on units representing 0.8% of the global coal-fired power plant capacity could reduce levels of PM2.5 emissions by 8–14%.

We find that 17% and 39% of the greenhouse gas emissions related to the cultivation of soybean feed for Brazilian pork and poultry, respectively, are embodied in exports to other countries, especially Eastern Europe, Asia and elsewhere in South America.

33% of premature deaths in China in 2010 (338,600 deaths) were caused by pollutants emitted in a different region of the country and transported in the atmosphere, and 56% (568,900 deaths) was related to consumption in another region.

Using a multivaritate probabilistic model, we quantify the average annual yields of major rainfed crops in Australia as a function of precipitation and soil moisture indices during the growing season. In the period 1980-2012, yields were 25–45% lower in dry seasons.

Jacobson et al. argue that wind, solar and hydro power alone could meet all U.S. energy demands at "low-cost." Unfortunately, their work contains errors, incorrect and unsupported assumptions, and inappropriate methods. It's possible to get all our energy from renewables, but Jacobson et al. haven't proven it'll be reliable or affordable.

We show that small increases mean temperatures may lead to big increases in heatwave deaths in India. For example, if summer mean temperatures increase by 0.5 °C, the chances of a heatwave that kills >100 people goes from roughly 1 in every 8 years to 1 in 3 years.

With its growing population, industrializing economy, and large coal reserves, India represents a critical unknown in global projections of future CO₂ emissions. As of mid-2016, proposed coal-fired power plants in India are incompatible with its NDC to reduce carbon intensity 33-35% by 2030.

In a groundbreaking interdisciplinary analysis, we quantify the global links among consumption of goods and services, production of air pollution, atmospheric transport of that pollution, and human mortality due to the pollution. We find that roughly a quarter of air pollution deaths are related to goods produced in one world region for consumption in another.

Globally, carbonating cement materials are a large, overlooked and growing sink of CO₂, which has offset 43% of the total process CO₂ emissions (excluding those from related fossil energy inputs) from production of cement between 1930 and 2013.

Earth system models suggest significant weakening, even potential reversal, of the ocean and land carbon sinks under future negative emission scenarios. Weakening of natural carbon sinks will hinder the effectiveness of negative emissions technologies and therefore increase their required deployment to achieve a given climate stabilisation target.

In recent years, international trade has displaced radiative forcing related to aerosols such as black carbon, sulfate, nitrate and ammonium from developed, net-importing nations like the U.S. to emerging, net-exporting nations like China. We quantify this shift and discuss its policy implications.

Existing technologies, institutions, and behavioral norms constrain the rate and magnitude of carbon emissions reductions in the coming decades. We review the implications of research on "carbon lock-in" for decarbonization efforts and propose a research agenda to bridge the gaps among science, knowledge and policy-making.

76 of the 77 (98.7%) scientists we surveyed had not encountered evidence of a secret, large-scale atmospheric spraying program, and said that purported evidence are more easily explained by well-understood physics and chemistry associated with aircraft contrails and atmospheric aerosols.

Benefits and costs of CO₂ emissions are often dislocated across space, time, and organizational level. When beneficiaries have greater political influence than those impacted, the result will be tragically suboptimal. Appeals to the consciences of beneficiaries will not solve the problem.

Commenting on our work decomposing drivers of recent trends in U.S. CO₂ emissions, Kotchen and Mansur confirm our results but take a 'glass is half-full' perspective on natural gas's role in the decline. Our reply further highlights what we think is wishful thinking.

Most scenarios that avoid 2°C of global warming require large-scale deployment of negative emissions technologies. We review the impacts and resource demands of such deployment, and conclude that it's cheaper, easier and less risky to tackle global warming before fossil CO₂ is in the atmosphere.

Emerging markets like China are increasingly financing expansion of fossil energy infrastructure in less-developed countries. The climate finance regime of the future should draw upon the resources of developing (as well as developed) countries to accelerate global low-carbon development.

China's coal-based energy system and emissions-intensive manufacturing technologies produce drastically more CO₂ emissions the same sectors in developed countries. We identify specific industries and provinces where improvements are most needed to reduce the CO₂-penalty of trade with China.

Using a simple model that includes infrastructural carbon lock-in, we show that avoiding 2 °C of warming with continued economic growth will require extremely low carbon intensity of new infrastructure--even with immediate action, relatively short infrastructure lifetimes, and the possibility of large negative emissions after 2050.

Peak warming will be proportional to cumulative CO₂ emissions, but the rate and velocity of climate change may be very different under different emissions pathways, even when cumulative emissions are equal. Thus, the ability of ecosystems to adapt or migrate is sensitive to the pathway of emissions.

Several thousand measurements of Chinese coal and clinker indicate that CO₂ emissions in China have been overestimated by 14% in recent years, or about 2.5 billion tons of CO₂ per year. This is a very large revision with important implications for international climate negotiations and assessments of the global carbon cycle.

Ecological restoration is big business, but there are few studies looking at the cost-effectiveness of different restoration methods. Using results from a large field experiment, we assess the resulting % native cover per dollar spent according to different methods of site prep, seeding and planting.

We present the results of a new bookkeeping model of land-use change emissions, BLUE, and use the model to show the large effects of different accounting decisions on estimated carbon fluxes.

US CO₂ emissions dropped 11% between 2007-2013;            a trend has been widely attributed to the increased use of natural gas over coal. We decompose the drivers of the decline and show that the recent economic downturn and not the gas boom deserves most of the credit for the decrease in emissions.

Large amounts of air pollution produced in the northern and central regions of China are embodied in goods imported by its affluent coastal provinces. This consumption-based accounting suggests that economically optimal pollution abatement efforts may need to assess embodied emissions.

Sustainable development depends upon understanding interactions among multiple complex subsystems, but scientific research tends to focus on one (or part of one) subsystem at a time. This review describes recent progress toward more integrated, interdisciplinary science that is problem-driven, solution-oriented, and intentionally policy-relevant, and then discusses future directions for this science.

More than 30 Mt CO₂-equivalent CH₄ and N₂O emissions were embodied in meat traded internationally in 2010, increasing at 4% per year. This reflects a trend of increasing livestock production in countries with lower input costs, less efficient practices, and more permissive environmental regulations, which decrease global food costs and increase demand.

A suite of global models show that, without new climate policies, abundant natural gas will not act to reduce GHG emissions or mitigate climate change. Consistent with our earlier findings for the US, abundant (and therefore cheap) gas may delay deployment of low-carbon energy sources and increase overall energy use.

Leaking methane isn't the only reason natural gas may not reduce GHG emissions: gas also competes against lower-carbon energy sources. Without targeted policy, gas substitutes for both coal and renewables and future US GHG emissions do not decline much even assuming no leakage.

We can estimate carbon budgets for different warming targets, but the lingering and contentious question is how to divvy up that budget among countries. Industrialized countries don't want to stop emitting and developing countries want to emit more. This paper proposes a quantitative method for doing the sharing.

Worldwide, existing power plants represent roughly 300 billion tons of future CO₂ emissions if all plants operate for 40 years, and these "committed emissions" in the power sector have been growing at a rate of ~4% per year. This paper proposes tracking these commitments to quantify future emissions implied by current investments.

Land use and use changes produce GHG emissions over years, during which the land may be used to produce different products. We review several methods of assigning land use emissions to specific products, which have dramatically different results. Analysts should communicate their choices and consider the implications in light of their goals.

A global accounting of GHG emissions from 11 livestock categories and 237 countries. Beef produces far more emissions than does pork or chicken. Emissions per unit of meat produced is decreasing in most places, but not quickly enough to keep up with rising global demand.

As much as a third of Chinese air pollution is related to goods exported from China, and some of that pollution blows across the Pacific to the US. Thus, outsourcing of manufacturing from the US to China has improved air quality in the eastern US, but has worsened air quality in the western US. [Cozzarelli Prize]

Goods and services consumed in one country increasingly depend upon fossil carbon extracted or burned in other countries. This limits the effectiveness of national climate policies that regulate only domestic emissions. Similarly, nations that depend on imports of fuels or emissions-intensive goods will bear costs of climate policies in exporting nations.

Rich coastal provinces in China outsource emissions to poorer interior provinces. China's province-specific emissions targets may encourage this dynamic even though the cheapest and easiest emissions reductions are in the less-developed interior provinces where the energy technologies in use are unsophisticated and inefficient.

Building on the influential "wedge" paper by Pacala and Socolow, we emphasize that stabilizing emissions is only the first step in solving climate change. Ultimately we have to stop dumping CO₂ into the atmosphere altogether; a phase-out of emissions over the next 50 years would require 19 wedges, and more if historical rates of technology improvement falter.

As part of the Global Carbon Project's RECCAP effort, Vanessa Haverd and co-authors quantified the terrestrial carbon budget of Australia, including emissions embodied in Aussie trade.

This paper synthesizes key differences between studies of CO₂ emissions in trade and provide a consistent set of estimates using the same definitions, modeling framework, and data. Included are new calculations of carbon physically present in trades wood, crop and livestock products.

Data from detrital zircon ages, paleocurrent trends, and sandstone petrofacies show that the Colton Formation in northeastern Utah represents the culmination of a persistent pattern of sediment transport northward during Cretaceous and Paleogene time (70-60 Ma).

CO₂ emissions from burning fossil fuels has increased steadily since fossil fuels were first used by humans. Despite international efforts, global emissions continue to increase at a rate of ~3% per year. This synthesis describes how emissions are calculated; calculates global, regional, and national emissions at different spatial and temporal scales; and discusses associated uncertainties.

Using nearly 5,000 oxygen isotope analyses performed over the past decade, we reconstruct the topographic development of western North America over the past 60 million years. The data shows that the landscape west of the modern Rockies grew into a rugged and high mountain range bordered on the west by a high Sierra Nevada Mountains and on the east by large lake basins that captured water draining these growing highlands.

Nations report CO₂ emissions from fossil fuels that are burned within their sovereign terrritory. But both fossil fuels and consumer goods manufactured with fossil energy are commonly transported internationally. We map global emissions according to where fossil fuel resources are extracted and where the goods made with fossil energy are consumed.

Fifty-five million years ago a river as big as the modern Colorado flowed through Arizona into Utah in the opposite direction from the present-day river. By analyzing the uranium and lead isotopes in sand grains made of the mineral zircon, we show that sediments in northeast Utah came from igneous bedrock in the Mojave region of southern California.

What if we never built another CO₂-emitting device, but the ones already in existence lived out their normal lives? We calculated the amount of carbon dioxide expected to be released from existing energy infrastructure worldwide, and then used a global climate model to project its effect on the Earth’s atmosphere and climate.

Agricultural intensification since 1961 has increased yields so much that the area in crops has not needed to change, even as demand has soared. As a consequence, intensification of agriculture has prevented deforestation that we estimate would otherwise have emitted 161 billion tons of carbon to the atmosphere.

Over a third of carbon dioxide emissions associated with consumption of goods and services in developed countries of western Europe, Japan, and the United States are emitted outside their borders, often in China. In contrast, ~24% of the emissions produced in China are exported.

This paper synthesizing hundreds of isotopic measurements from the Paleogene (~65-40 Ma) North American Cordillera to reconstruct the evolving hydrology of the Eocene Green River Lake system and shifting Cordilleran drainage patterns as the modern topography of the Rocky Mountains developed.

The isotopic composition of 40-60 million year-old lake deposits in Utah may reflect the north-to-south progression of topography and drainage rearrangements as magmatism swept southward through Montana and Nevada and increased the mean elevation of catchments that drained east into the lakes of Utah.

Lakes in the Laramide foreland co-evolved with drainage patterns. Such shifting drainages could confound isotopic estimates of paleoaltimetry. In the North American Cordillera of the Paleogene, for instance, it's likely that (1) changing topography in areas hundred of kilometers from foreland lakes altered isotopic composition of lake water.

A report of The Climate Conservancy, which I co-founded with a goal to label consumer products with their carbon footprints. This work was conducted with data from New Belgium Brewing Company, for whom we assessed the carbon footprint of the well-known Fat Tire Amber Ale. We prepared a detailed report.