Greenhouse Gas Emission Pathways Research Articles

Call for emergency action to limit global temperature increases, restore biodiversity, and protect health

Call for emergency action to limit global temperature increases, restore biodiversity, and protect health

Call for emergency action to limit global temperature increases, restore biodiversity, and protect health

Call for emergency action to limit global temperature increases, restore biodiversity, and protect health

The Impact of U.S. Re‐engagement in Climate on the Paris Targets

AbstractThe Paris Agreement seeks to combine international efforts to keep global temperature increase to well‐below 2°C. Whilst current ambitions in many signatories are insufficient to achieve this goal, optimism prevailed in the second half of 2020. Not only did several major emitters announce net‐zero mitigation targets around mid‐century, but the new Biden Administration immediately announced the U.S.’s re‐entry into Paris and a net‐zero goal for 2050. U.S. federal re‐engagement in climate action could have a considerable impact on its national greenhouse gas emissions pathway, by significantly augmenting existing state‐level actions. Combined with U.S. re‐entry in the Paris Agreement, this could also serve as a stimulus to enhance ambitions in other countries. A critical question then becomes what such U.S. re‐engagement, through both national and international channels, would have on the global picture. This commentary explores precisely this question, by using an integrated assessment model to assess U.S. national emissions, global emissions, and end‐of‐century temperatures in five scenarios combining different climate ambition levels in both the U.S. and the rest of the world. Our analyses finds that ambitious climate leadership by the Biden Administration on top of enhanced climate commitments by other the major economies could potentially be the trigger for the world to fulfill the temperature goal of the Paris Agreement.

Cutting through the noise on negative emissions

Cutting through the noise on negative emissions

Comparing CO2 emissions impacts of electricity storage across applications and energy systems

Summary Electricity storage systems can support the decarbonization of energy systems. However, the effect of electricity storage use on greenhouse gas emissions is complex because of roundtrip efficiency losses of the storage and its effects on the dispatch of different electricity-generation technologies. The limited literature examining this issue focus on individual electricity storage applications and the geographies where they are applied. Here, we systematically compare the effects of electricity storage on CO2 emissions across four applications in electricity systems resembling seven European countries. Our findings reveal large emission impact differences between applications and countries. Among other findings, we find that when compared with wholesale arbitrage, storing electricity in other applications exhibits much lower effects on CO2 emissions. We also investigate different policy options to reduce CO2 emissions from storing electricity. We find that although a higher carbon price can have a substantial effect on reducing the CO2 emissions from wholesale arbitrage, other applications require alternative approaches.

Assessing nature-based solutions for transformative change

Assessing nature-based solutions for transformative change

Low-carbon production of iron and steel: Technology options, economic assessment, and policy

Summary Given increased urgency to transition the global economy to net-zero CO2 emission, governments and industry have increased focus on decarbonizing hard-to-abate sectors, including steel making, which contributes roughly 6% of global CO2 emission and 8% of energy-related emission (including power consumption emission). This paper reviews current global iron and steel production and assesses available decarbonization technologies, including hydrogen injection, solid biomass substitution, zero-C electricity substitution, carbon capture and storage (CCS) retrofit, and combinations of these decarbonization approaches. Blast furnace-basic oxygen furnace (BF-BOF) dominates production (71%) and is particularly stubborn to any decarbonization technology. Direct reduced iron to electric arc furnace (DRI-EAF) production is 5% and growing, it appears to have better decarbonization potential to move toward net-zero. Secondary steel production using mainly steel scrap in electric arc furnace (EAF-scrap) is 24% of global production and has both the lowest energy consumption and is technically simplest to decarbonize through electrification but is limited in market share to recycled steel capacity. Of the options assessed, blue hydrogen, carbon neutral biomass, and CCS appear to have the lowest cost and highest technical maturity. However, no single approach today can deliver deep decarbonization to the iron and steel industry and all approaches lead to substantial production cost increase. No uniform ideal solution exists, and different geographies, infrastructure, and economies will determine the local optimum solution with viability and cost. Policy measures will be required to provide financial incentives for decarbonization and to avoid unwelcome outcomes such as emissions leakage or job loss.

Accelerating towards net zero emissions: the most important global health intervention

Accelerating towards net zero emissions: the most important global health intervention

Assessment of greenhouse gas mitigation pathways for Thailand towards achievement of the 2°C and 1.5°C Paris Agreement targets

ABSTRACT This study performed scenario analysis using the MARKAL modelling framework to assess Thailand’s greenhouse gas (GHG) emission pathways over the period 2010–2050, to explore the possibilities of achieving carbon neutrality of the energy system by 2060–2100, in pursuit of a maximum temperature rise of 2°C and 1.5°C by the end of the century. The shift from 2°C pathways to 1.5°C pathways would demand much more effort and pose greater challenges in terms of transformational changes required in the energy supply and demand sectors of Thailand. Carbon neutrality in the energy supply system would be achievable with negative emissions through the adoption of bioenergy with carbon capture and storage (BECCS). The strong deployment of renewable energy-based power generation would also aid in the rapid decarbonization of the energy supply sector. The demand sectors would face more challenges requiring rapid and extensive deployment of energy efficient and low carbon technologies. The commercial sector may need to undergo deep decarbonization in the 1.5°C scenarios by 2050 while the industrial and residential sectors will need to curb GHG emissions by a large amount even under 2°C scenarios. The transportation sector would face challenges in shifting from private to public modes of transport, including wide adoption of electric and biofuel vehicles, in order to achieve the 1.5°C target. Key Policy insights The attainment of 2°C and 1.5°C targets demand for a wide scale adoption of BECCS in Thailand resulting in negative emissions in the power sector even before 2050. Biomass, solar photovoltaics, and wind power would make up to the largest portion in the total power generation mix of Thailand in the 2°C and 1.5°C scenarios by 2050. Achieving carbon neutrality of the energy system by 2060–2100 is a challenging task for Thailand requiring higher investments and supportive policy actions to promote renewables, carbon capture and storage technologies, and energy efficiency enhancements.

De-risking Renewable Energy Investments in Developing Countries: A Multilateral Guarantee Mechanism

Summary Mitigation of global warming requires substantial investment in electricity generation from renewable sources. A large share of new generation capacity is required in regions with adverse financing conditions. We propose a global guarantee mechanism to reduce risk premia of renewable energy investments by means of risk pooling and increased market efficiency. Policymakers could establish this mechanism by scaling up existing international risk guarantee initiatives. We estimate the net present value of overall savings at US$2018 1.5 trillion globally for investments by 2030, with the largest relative savings (between 20.5% and 22%) in Sub-Saharan Africa and the Maghreb. The savings from such a mechanism outweigh its estimated average yearly operating cost. By lowering the cost of decarbonization in high-risk countries, the proposed mechanism offers policymakers a tool to make current global mitigation pledges more achievable and enables the global community to pursue more ambitious climate action.

Temperature and rainfall extremes change under current and future global warming levels across Indian climate zones

Mean surface temperature is projected to rise by about 4.4 °C by the end of the century compared to the period between 1976 and 2005 when following the most extreme scenario of the greenhouse gas emissions pathway (Krishnan et al., 2020). With this rise in mean temperature, there is a lot of uncertainty on how weather and climate extremes would unfold, especially for various climate zones of India. It is therefore essential that the potential changes in both magnitude and direction of weather and climate extremes at the regional level when the global temperature reaches the different warming levels from 1 °C to 3 °C be established to allow for informed policy formulation.The present study explores the potential changes in the Expert Team on Climate Change Detection and Indices of rainfall and temperature estimated from the coupled model inter-comparison project CMIP5 multi-model ensemble over different climatic zones of India at 1 °C, 1.5 °C, 2 °C, 2.5 °C and 3 °C global temperature rise relative to pre-industrial levels under two Representative Concentration Pathways, RCP4.5 and RCP8.5. Projected changes in temperature extremes indicate significant changes at all warming levels across the nine climate zones of India. Hot temperature extremes are expected to increase while cold temperature extremes decrease. For India, country average at 3 °C under the RCP8.5 and 2 °C under the RCP4.5 scenarios, ensemble median shows that Warm Spell Duration Index will increase by 131 days and 66 days; hot days increase by 44% and 52%, warm nights increase by 23% and 13%; cold days decrease by 10% and 9%, and cold nights decrease by 13% and 12% relative to pre-industrial levels. The greatest changes in temperature based indices are projected in the colder northern parts of the country followed by the arid zone. Ensemble median for rainfall indices shows an increase in high precipitation indices, though with large model spread indicating the large uncertainties in the projections. Annual total precipitation and heavy rainfall related extreme indices show statistically significant increases in the tropical, temperate and semi-arid regions of India, moving from 1 °C to 3 °C warming level under RCP8.5 scenario whereas there is generally no significant change in the maximum number of consecutive dry and wet days.Moreover, the potential changes in climate extremes at the regional level are expected to have far-reaching impacts on the social and economic statuses of the respective climate zones. This information at a regional scale also calls attention to the national and state action plan on climate change and adaptation to be more responsive in order to take coherent and integrated policy decisions.

Modelling food demand in the 21st century

Modelling food demand in the 21st century

Moving toward Net-Zero Emissions Requires New Alliances for Carbon Dioxide Removal

The 1.5°C target will require removing at least some of the carbon dioxide (CO2) previously emitted. Knowledge on how this can be done has been increasing, though barriers remain concerning governance, policy, and acceptability. For the 26th session of the Conference of the Parties (COP26) to move beyond an academic debate on CO2 removal (CDR), a broader alliance of research and policy communities, industry, and the public is needed.

How Behavioral Interventions Can Reduce the Climate Impact of Energy Use

Kristian S. Nielsen is a research associate in the Department of Zoology at University of Cambridge. He received a PhD from Copenhagen Business School in 2019 with a dissertation focused on the role of self-regulation in environmental behavior change. His current research focuses on bridging research in behavioral science and biodiversity conservation as part of an interdisciplinary project called Nudging for Nature. His other research interests revolve around behavior change as a climate change mitigation strategy, the dynamics of the behavior change process, self-regulation and self-control, and sustainable clothing consumption. Sander van der Linden is Reader in Social Psychology in Society and director of the Cambridge Social Decision-Making Lab in the Department of Psychology at the University of Cambridge. He is also a fellow in Psychological and Behavioral Sciences at Churchill College, Cambridge and the editor-in-chief of the Journal of Environmental Psychology. His research on the psychology of human judgment and decision-making, especially in the context of climate change, has received numerous awards including the Rising Star award from the Association for Psychological Science and the Sage Early Career Award from the Society for Personality and Social Psychology . Paul C. Stern is president of the Social and Environmental Research institute and was previously a principal staff officer at the US National Academy of Science, Engineering, and Medicine where he directed its Board on Environmental Change and Society. He is a fellow of the American Association for the Advancement of Science and the American Psychological Association. His research interests include the integration of social science into research and practice for governing environmental change and into risk assessment and management. Among his publications are Environmental Problems and Human Behavior (coauthor) and Understanding Risk: Informing Decisions in a Democratic Society (coeditor).

The Lancet–Chatham House Commission on improving population health post COVID-19

The Lancet–Chatham House Commission on improving population health post COVID-19

Predicting the potential distribution of the parasitic Cuscuta chinensis under global warming

BackgroundThe climate is the dominant factor that affects the distribution of plants. Cuscuta chinensis is a stem holoparasitic plant without leaves or roots, which develops a haustorium and sucks nutrients from host plants. The potential distribution of the parasitic plant C. chinensis has not been predicted to date. This study used Maxent modeling to predict the potential global distribution of C. chinensis, based on the following six main bioclimatic variables: annual mean temperature, isothermality, temperature seasonality, precipitation seasonality, precipitation of the warmest quarter, and precipitation of the coldest quarter.ResultsThe optimal annual average temperature and isothermality of C. chinensis ranged from 4 to 37 °C and less than 45, respectively, while the optimal temperature seasonality and precipitation seasonality ranged from 4000 to 25,000 and from 50 to 130, respectively. The optimal precipitation of the warmest season ranged from 300 to 1000 mm and from 2500 to 3500 mm, while that of the coldest season was less than 2000 mm. In Asia, C. chinensis is mainly distributed at latitudes ranging from 20° N to 50° N. During three specific historical periods (last glacial maximum, mid-Holocene, and 1960–1990) the habitats suitable for C. chinensis were concentrated in the central, northern, southern, and eastern parts of China. From the last glacial maximum to the mid-Holocene, the total area with suitability of 0.5–1 increased by 0.0875 million km2; however, from the mid-Holocene to 1960–1990, the total area with suitability of 0.5–1 decreased by 0.0759 million km2. The simulation results of habitat suitability in the two representative concentration pathways (RCP) 2.6 (i.e., the low greenhouse gas emissions pathway) and 8.5 (i.e., the high greenhouse gas emissions pathway) indicate that the habitat suitability of C. chinensis decreased in response to the warming climate. Compared with RCP2.6, areas with averaged suitability and high suitability for survival (RCP8.5) decreased by 0.18 million km2.ConclusionSuitable habitats of C. chinensis are situated in central, northern, southern, and eastern China. The habitat suitability of C. chinensis decreased in response to the warming climate. These results provide a reference for the management and control of C. chinensis.

Emulating Earth system model temperatures with MESMER: from global mean temperature trajectories to grid-point-level realizations on land

Abstract. Earth system models (ESMs) are invaluable tools to study the climate system's response to specific greenhouse gas emission pathways. Large single-model initial-condition and multi-model ensembles are used to investigate the range of possible responses and serve as input to climate impact and integrated assessment models. Thereby, climate signal uncertainty is propagated along the uncertainty chain and its effect on interactions between humans and the Earth system can be quantified. However, generating both single-model initial-condition and multi-model ensembles is computationally expensive. In this study, we assess the feasibility of geographically explicit climate model emulation, i.e., of statistically producing large ensembles of land temperature field time series that closely resemble ESM runs at a negligible computational cost. For this purpose, we develop a modular emulation framework which consists of (i) a global mean temperature module, (ii) a local temperature response module, and (iii) a local residual temperature variability module. Based on this framework, MESMER, a Modular Earth System Model Emulator with spatially Resolved output, is built. We first show that to successfully mimic single-model initial-condition ensembles of yearly temperature from 1870 to 2100 on grid-point to regional scales with MESMER, it is sufficient to train on a single ESM run, but separate emulators need to be calibrated for individual ESMs given fundamental inter-model differences. We then emulate 40 climate models of the Coupled Model Intercomparison Project Phase 5 (CMIP5) to create a “superensemble”, i.e., a large ensemble which closely resembles a multi-model initial-condition ensemble. The thereby emerging ESM-specific emulator parameters provide essential insights on inter-model differences across a broad range of scales and characterize core properties of each ESM. Our results highlight that, for temperature at the spatiotemporal scales considered here, it is likely more advantageous to invest computational resources into generating multi-model ensembles rather than large single-model initial-condition ensembles. Such multi-model ensembles can be extended to superensembles with emulators like the one presented here.

CO2-to-Fuels Renewable Gasoline and Jet Fuel Can Soon Be Price Competitive with Fossil Fuels

Download : Download high-res image (69KB) Download : Download full-size image Rob McGinnis, PhD, is an inventor and entrepreneur. He is the founder and CEO of Prometheus, a company that is developing technology to remove carbon dioxide from the air and turn it into fuels. He previously founded Mattershift, where he developed large-scale carbon nanotube membranes. Rob was previously founder of Oasys Water, a company focused on developing forward osmosis technologies for water purification. Rob received his PhD in Engineering from Yale University.

Emergent constraints on Earth’s transient and equilibrium response to doubled CO2 from post-1970s global warming

Future global warming is determined by both greenhouse gas emission pathways and Earth’s transient and equilibrium climate response to doubled atmospheric CO2. Energy-balance inference from the instrumental record typically yields central estimates for the transient response of around 1.3 K and the equilibrium response of 1.5–2.0 K, which is at the lower end of those from contemporary climate models. Uncertainty arises primarily from poorly known aerosol-induced cooling since the early industrialization era and a temporary cooling induced by evolving sea surface temperature patterns. Here we present an emergent constraint on post-1970s warming, taking advantage of the weakly varying aerosol cooling during this period. We derive a relationship between the transient response and the post-1970s warming in Coupled Model Intercomparison Project Phase 5 (CMIP5) models. We thereby constrain, with the observations, the transient response to 1.67 K (1.17–2.16 K, 5–95th percentiles). This is a 20% increase relative to energy-balance inference stemming from previously neglected upper-ocean energy storage. For the equilibrium climate sensitivity we obtain a best estimate of 2.83 K (1.72–4.12 K) contingent on the temporary pattern effects exhibited by climate models. If the real world’s surface temperature pattern effects are substantially stronger, then the upper-bound equilibrium sensitivity may be higher than found here. Warming in climate simulations since about 1970, when aerosol cooling showed little variation, constrains the transient climate response to doubled atmospheric CO2 levels to about 1.67 K, according to an analysis of this emergent constraint.

Shift in seasonal climate patterns likely to impact residential energy consumption in the United States

We develop a highly-resolved ensemble of climate simulations and empirical relationships between weather and household energy consumption to provide one of the most detailed estimates to date for potential climate-driven changes in the United States residential energy demand under the highest greenhouse gas emissions pathway. Our results indicate that more intense and prolonged warm conditions will drive an increase in electricity demand while a shorter and milder cold season will reduce natural gas demand by the mid 21st century. The environmental conditions that favor more cooling degree days in summer and reduced heating degree days in winter are driven by changes in daily maximum temperatures and daily minimum temperatures in the respective seasons. Our results also indicate that climate-driven change can potentially reverse impacts of a projected decrease in rural population on residential energy demand. These projected changes in climate-driven energy demand have implications for future energy planning and management.