Emission Budget Research Articles

PMIF v1.0: assessing the potential of satellite observations to constrain CO<sub>2</sub> emissions from large cities and point sources over the globe using synthetic data

Abstract. This study assesses the potential of satellite imagery of vertically integrated columns of dry-air mole fractions of CO2 (XCO2) to constrain the emissions from cities and power plants (called emission clumps) over the whole globe during 1 year. The imagery is simulated for one imager of the Copernicus mission on Anthropogenic Carbon Dioxide Monitoring (CO2M) planned by the European Space Agency and the European Commission. The width of the swath of the CO2M instruments is about 300 km and the ground horizontal resolution is about 2 km resolution. A Plume Monitoring Inversion Framework (PMIF) is developed, relying on a Gaussian plume model to simulate the XCO2 plumes of each emission clump and on a combination of overlapping assimilation windows to solve for the inversion problem. The inversion solves for the 3 h mean emissions (during 08:30–11:30 local time) before satellite overpasses and for the mean emissions during other hours of the day (over the aggregation between 00:00–08:30 and 11:30–00:00) for each clump and for the 366 d of the year. Our analysis focuses on the derivation of the uncertainty in the inversion estimates (the “posterior uncertainty”) of the clump emissions. A comparison of the results obtained with PMIF and those from a previous study using a complex 3-D Eulerian transport model for a single city (Paris) shows that the PMIF system provides the correct order of magnitude for the uncertainty reduction of emission estimates (i.e., the relative difference between the prior and posterior uncertainties). Beyond the one city or few large cities studied by previous studies, our results provide, for the first time, the global statistics of the uncertainty reduction of emissions for the full range of global clumps (differing in emission rate and spread, and distance from other major clumps) and meteorological conditions. We show that only the clumps with an annual emission budget higher than 2 MtC yr−1 can potentially have their emissions between 08:30 and 11:30 constrained with a posterior uncertainty smaller than 20 % for more than 10 times within 1 year (ignoring the potential to cross or extrapolate information between 08:30–11:30 time windows on different days). The PMIF inversion results are also aggregated in time to investigate the potential of CO2M observations to constrain daily and annual emissions, relying on the extrapolation of information obtained for 08:30–11:30 time windows during days when clouds and aerosols do not mask the plumes, based on various assumptions regarding the temporal auto-correlations of the uncertainties in the emission estimates that are used as a prior knowledge in the Bayesian framework of PMIF. We show that the posterior uncertainties of daily and annual emissions are highly dependent on these temporal auto-correlations, stressing the need for systematic assessment of the sources of uncertainty in the spatiotemporally resolved emission inventories used as prior estimates in the inversions. We highlight the difficulty in constraining the total budget of CO2 emissions from all the cities and power plants within a country or over the globe with satellite XCO2 measurements only, and calls for integrated inversion systems that exploit multiple types of measurements.

Tracers for evaluating computational models of atmospheric transport and oxidation at regional to global scales

Atmospheric tracers are effective tools for characterizing dispersion and for testing computational models of atmospheric transport. Atmospheric trace gas measurements are now used widely to infer geographical surface flux distributions. However, robust flux estimates critically rely on well-validated knowledge of atmospheric chemistry, loss processes and transport, without which we are not fully realizing the potential of atmospheric measurements collected on the ground, or from aircraft and satellites. This challenge has taken on renewed importance in the shadow of the Paris Agreement that will likely take advantage of atmospheric trace gas measurements to help improve national and global greenhouse gas emission budgets. We describe a wide range of existing and new potential atmospheric tracers for improving our understanding of atmospheric dispersion. We consider the investigation of atmospheric transport over two scales: (1) short-to-medium length scale (on the order of 1–1000 km) to improve our understanding of convection and boundary layer transport processes, and (2) hemisphere-to-global length scale (on the order of 1000–10,000 km), where large-scale mixing, cross hemisphere transport and stratosphere-troposphere exchange are important. Although we note the possibility of using “tracers of opportunity,” our primary focus is on deliberate-release tracers, and we explore the use of cyclic perfluorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroethers and novel tracers of deuterium-substituted halocarbons. We examine how we might exploit existing instrumentation already deployed at remote global monitoring sites as well as requirements for new instrumentation. To guide the discussion, we provide example scenarios for how experiments might be set up, covering regional to global spatial scales for the evaluation and improvement of atmospheric transport models. However, we stress that appropriate three-dimensional modelling studies and preliminary experiments would need to be carried out to determine the specific details of any real-world experiment.

Elevated CO2 Emissions during Magmatic-Hydrothermal Degassing at Awu Volcano, Sangihe Arc, Indonesia

Awu is a remote and little known active volcano of Indonesia located in the northern part of Molucca Sea. It is the northernmost active volcano of the Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of 11,048. Two of these eruptions were classified with a Volcanic Explosivity Index (VEI) of 4. Since 2004, a lava dome has occupied the centre of Awu crater, channelling the fumarolic gas output along the crater wall. A combined Differential Optical Absorption Spectroscopy (DOAS) and Multi-component Gas Analyzer System (Multi-GAS) study highlight a relatively small SO2 flux (13 t/d) sustained by mixed magmatic–hydrothermal emissions made-up of 82 mol.% H2O, 15 mol.% CO2, 2.55 mol.% total S (ST) and 0.02 mol.% H2. The CO2 emission budget, as observed during a short observation period in 2015, corresponds to a daily contribution to the atmosphere of 2600 t/d, representing 1% of the global CO2 emission budget from volcanoes. The gas CO2/ST ratio of 3.7 to 7.9 is at the upper limit of the Indonesian gas range, which is ascribed to (i) some extent of S loss during hydrothermal processing, and perhaps (ii) a C-rich signature of the feeding magmatic gas phase. The source of this high CO2 signature and flux is yet to be fully understood; however, given the peculiar geodynamic context of the region, dominated by the arc-to-arc collision, this may result from either the prolonged heating of the slab and consequent production of carbon-rich fluids, or the recycling of crustal carbon.

Towards an Improved Inventory of N2O Emissions Using Land Cover Maps Derived from Optical Remote Sensing Images

Agricultural soils are the primary anthropogenic source of N2O emissions, one of the most important greenhouse gases, because of the use of nitrogen (N) fertilizers. The proposed method provides access to an inventory of potential N2O emissions (the term potential refers to possible but not yet actual) at a fine scale, with an annual update, without a heavy deployment linked to a collection of field measurements. The processing chain is applied to optical satellite images regularly acquired at a high spatial resolution during the 2006–2015 period, allowing a better spatial and temporal resolution of the estimates of potential N2O emissions from crops. The yearly potential N2O emissions inventory is estimated over a study site located in southwestern France, considering seven main seasonal crops (i.e., wheat, barley, rapeseed, corn, sunflower, sorghum and soybean). The first step of the study, that is the land use classification, is associated with accurate performances, with an overall accuracy superior to 0.81. Over the study area, the yearly potential budget of N2O emissions ranges from 97 to 113 tons, with an estimated relative error of less than 5.5%. Wheat, the main cultivated crop, is associated with the maximum cumulative emissions regardless of the considered year (with at least 48% of annual emissions), while maize, the third crop regarding to the allocated area (grown on less than 8% of the study site), has the second highest cumulative emissions. Finally, the analysis of a 10-year map of the potential N2O budget shows that the mainly observed crop rotation (i.e., alternating of wheat and sunflower) reaches potential emissions close to 16 kg N2O emitted per hectare, while the monoculture maize is associated with the maximum value (close to 28.9 kg per hectare).

Electrification of light-duty vehicle fleet alone will not meet mitigation targets

Climate change mitigation strategies are often technology-oriented, and electric vehicles (EVs) are a good example of something believed to be a silver bullet. Here we show that current US policies are insufficient to remain within a sectoral CO2 emission budget for light-duty vehicles, consistent with preventing more than 2 °C global warming, creating a mitigation gap of up to 19 GtCO2 (28% of the projected 2015–2050 light-duty vehicle fleet emissions). Closing the mitigation gap solely with EVs would require more than 350 million on-road EVs (90% of the fleet), half of national electricity demand and excessive amounts of critical materials to be deployed in 2050. Improving average fuel consumption of conventional vehicles, with stringent standards and weight control, would reduce the requirement for alternative technologies, but is unlikely to fully bridge the mitigation gap. There is therefore a need for a wide range of policies that include measures to reduce vehicle ownership and usage. Electric vehicles (EV) are often considered as the best chance for reducing light-duty transport emissions. Analysis of US policies shows that required emission reductions exceed feasible EV deployment, and technology alongside behaviour change is needed.

Seasonality and Budgets of Soil Greenhouse Gas Emissions From a Tropical Dry Forest Successional Gradient in Costa Rica

AbstractLimited information on greenhouse gas emissions from tropical dry forest soils still hinders the assessment of the sources/sinks from this ecosystem and their contribution at global scales. Particularly, rewetting events after the dry season can have a significant effect on soil biogeochemical processes and associated exchange of greenhouse gases. This study evaluated the temporal variation and annual fluxes of CO2, N2O, and CH4 from soils in a tropical dry forest successional gradient. After a prolonged drought of 5 months, large emissions pulses of CO2 and N2O were observed at all sites following first rain events, caused by the “Birch effect,” with a significant effect on the net ecosystem exchange and the annual emissions budget. Annual CO2 emissions were greatest for the young forest (8,556 kg C ha−1 yr−1) followed by the older forest (7,420 kg C ha−1 yr−1) and the abandoned pasture (7,224 kg C ha−1 yr−1). Annual emissions of N2O were greatest for the forest sites (0.39 and 0.43 kg N ha−1 yr−1) and least in the abandoned pasture (0.09 kg N ha−1 yr−1). CH4 uptake was greatest in the older forest (−2.61 kg C ha−1 yr−1) followed by the abandoned pasture (−0.69 kg C ha−1 yr−1) and the young forest (−0.58 kg C ha−1 yr−1). Fluxes were mainly influenced by soil moisture, microbial biomass, and soil nitrate and ammonium concentrations. Annual CO2 and N2O soil fluxes of tropical dry forests in this study and others from the literature were much lower than the annual fluxes in wetter tropical forests. Conversely, tropical dry forests and abandoned pastures are on average stronger sinks for CH4 than wetter tropical forests.

The Political Economy of Deep Decarbonization: Tradable Energy Quotas for Energy Descent Futures

This paper reviews and analyses a decarbonization policy called the Tradable Energy Quotas (TEQs) system developed by David Fleming. The TEQs system involves rationing fossil fuel energy use for a nation on the basis of either a contracting carbon emission budget or scarce fuel availability, or both simultaneously, distributing budgets equitably amongst energy-users. Entitlements can be traded to incentivize demand reduction and to maximize efficient use of the limited entitlements. We situate this analysis in the context of Joseph Tainter’s theory about the development and collapse of complex societies. Tainter argues that societies become more socio-politically and technologically ‘complex’ as they solve the problems they face and that such complexification drives increased energy use. For a society to sustain itself, therefore, it must secure the energy needed to solve the range of societal problems that emerge. However, what if, as a result of deep decarbonization, there is less energy available in the future not more? We argue that TEQs offers a practical means of managing energy descent futures. The policy can facilitate controlled reduction of socio-political complexity via processes of ‘voluntary simplification’ (the result being ‘degrowth’ or controlled contraction at the scale of the physical economy).

Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming

As global temperatures continue to rise, a key uncertainty of climate projections is the microbial decomposition of vast organic carbon stocks in thawing permafrost soils. Decomposition rates can accelerate up to fourfold in the presence of plant roots, and this mechanism—termed the rhizosphere priming effect—may be especially relevant to thawing permafrost soils as rising temperatures also stimulate plant productivity in the Arctic. However, priming is currently not explicitly included in any model projections of future carbon losses from the permafrost area. Here, we combine high-resolution spatial and depth-resolved datasets of key plant and permafrost properties with empirical relationships of priming effects from living plants on microbial respiration. We show that rhizosphere priming amplifies overall soil respiration in permafrost-affected ecosystems by ~12%, which translates to a priming-induced absolute loss of ~40 Pg soil carbon from the northern permafrost area by 2100. Our findings highlight the need to include fine-scale ecological interactions in order to accurately predict large-scale greenhouse gas emissions, and suggest even tighter restrictions on the estimated 200 Pg anthropogenic carbon emission budget to keep global warming below 1.5 °C.

Towards spaceborne monitoring of localized CO<sub>2</sub> emissions: an instrument concept and first performance assessment

Abstract. The UNFCCC (United Nations Framework Convention on Climate Change) requires the nations of the world to report their carbon dioxide (CO2) emissions. The independent verification of these reported emissions is a cornerstone for advancing towards the emission accounting and reduction measures agreed upon in the Paris Agreement. In this paper, we present the concept and first performance assessment of a compact spaceborne imaging spectrometer with a spatial resolution of 50×50 m2 that could contribute to the “monitoring, verification and reporting” (MVR) of CO2 emissions worldwide. CO2 emissions from medium-sized power plants (1–10 Mt CO2 yr−1), currently not targeted by other spaceborne missions, represent a significant part of the global CO2 emission budget. In this paper we show that the proposed instrument concept is able to resolve emission plumes from such localized sources as a first step towards corresponding CO2 flux estimates. Through radiative transfer simulations, including a realistic instrument noise model and a global trial ensemble covering various geophysical scenarios, it is shown that an instrument noise error of 1.1 ppm (1σ) can be achieved for the retrieval of the column-averaged dry-air mole fraction of CO2 (XCO2). Despite a limited amount of information from a single spectral window and a relatively coarse spectral resolution, scattering by atmospheric aerosol and cirrus can be partly accounted for in the XCO2 retrieval, with deviations of at most 4.0 ppm from the true abundance for two-thirds of the scenes in the global trial ensemble. We further simulate the ability of the proposed instrument concept to observe CO2 plumes from single power plants in an urban area using high-resolution CO2 emission and surface albedo data for the city of Indianapolis. Given the preliminary instrument design and the corresponding instrument noise error, emission plumes from point sources with an emission rate down to the order of 0.3 Mt CO2 yr−1 can be resolved, i.e., well below the target source strength of 1 Mt CO2 yr−1. This leaves a significant margin for additional error sources, like scattering particles and complex meteorology, and shows the potential for subsequent CO2 flux estimates with the proposed instrument concept.

Climate-induced challenges of Norway spruce in Northern Austria

A dramatic increase in bark-beetle (Ips typographus) damage in Norway spruce (Picea abies (L.) Karst.) forests occured in the provinces Upper and Lower Austria in the past decade with the beetle outbreak likely driven by climate change. Water shortage in the early growing season appears to weaken the forests. The high supply of beetle-infested timber is reducing wood prices and forests are not meeting policy expectations for a viable bioeconomy. The sink strength of forests has diminished from 12% to 6% of the national greenhouse gas emission budget and may even turn into a source when the disturbance dynamics continue. Consequences cascade through the forest sector. The regional market price for bark-beetle affected timber declined to 30% of the previous level. Small-forest owners who obtain a marginal income from wood products are losing motivation for active forest management. The operational difficulties of cutting affected trees combined with the organization of timber transport to saw-mills are being met by excessive inventories of unprocessed logs at mills. Large forest enterprises can only intermittently absorb higher costs for forest management than be met currently from sales of products. The long-term consequence is lasting reduction of forest productivity and an uncertain future for forestry in Central Europe that may increasingly depend on technological breakthroughs in processing timber from deciduous trees and eventually payments for ecosystem services.

A Structured Approach for the Mitigation of Natural Methane Emissions—Lessons Learned from Anthropogenic Emissions

Methane is the second most important greenhouse gas. Natural methane emissions represent 35–50% of the global emissions budget. They are identified, measured and categorized, but, in stark contrast to anthropogenic emissions, research on their mitigation is largely absent. To explain this, 18 problems are identified and presented. This includes problems related to the emission characteristics, technological and economic challenges, as well as problems resulting from a missing framework. Consequently, strategies, methods and solutions to solve or circumvent the identified problems are proposed. The framework covers definitions for methane source categorization and for categories of emission types and mitigation approaches. Business cases for methane mitigation are discussed and promising mitigation technologies briefly assessed. The importance to get started with methane mitigation in the different areas is highlighted and avenues for doing so are presented.

First characterization of Gamkonora gas emission, North Maluku, East Indonesia

Gamkonora is an active volcano capable of intense manifestations that regularly forced thousands of inhabitants to flee their villages. The most extreme eruption, in 1673, was a VEI 5 event that induced pitch-dark environment over the region. Paradoxically, little is known about Gamkonora volcano and here we present the first gas measurement results obtained in September 2018 using a MultiGAS and a scanning DOAS. Results highlight a relatively small but magmatic gas with a CO2/ST of 3.5, in the range of high-temperature gas emissions from Indonesian volcanoes and H2O/SO2, CO2/SO2, H2S/SO2, and H2/SO2 ratios of 135, 5.6, 0.6, and 0.2, respectively. The daily gas emission budget corresponds to 129 t, 13 t, 3.4 t, 1.1 t, and 0.03 t for H2O, CO2, SO2, H2S, and H2, respectively. Bulk rock analyses indicate a basaltic andesite to andesite source beneath Gamkonora.

Variability of BVOC Emissions from Commercially Used Willow (Salix spp.) Varieties

Willow (Salix spp.) trees are commonly used in short rotation coppices (SRC) to produce renewable energy. However, these plants are also known to emit high concentrations of biogenic volatile organic compounds (BVOCs), which have a large influence on air quality. Many different clones of commercially used Salix varieties exist today, but only a few studies have focused on BVOC emissions from these newer varieties. In this study, four varieties commercially propagated for biofuel production have been studied on a leaf-scale in the southern part of Sweden. The trees had either their first or second growing season, and measurements on BVOC emissions were done during the growing season in 2017 from the end of May to the beginning of September. Isoprene was the dominant emitted compound for all varieties but the average emission amongst varieties varied from 4.00 to 12.66 µg gdw−1 h−1. Average monoterpene (MT) (0.78–1.87 µg gdw−1 h−1) and sesquiterpene (SQT) emission rates (0.22–0.57 µg gdw−1 h−1) differed as well among the varieties. Besides isoprene, other compounds like ocimene, linalool and caryophyllene also showed a response to light but not for all varieties. Younger plants had several times higher emissions of non-isoprenoids (other VOCs) than the corresponding 1-year-old trees. The conclusions from this study show that the choice of variety can have a large impact on the regional BVOC emission budget. Genetics, together with stand age, should be taken into account when modelling BVOC emissions on a regional scale, for example, for air quality assessments.

Demonstrating GWP*: a means of reporting warming-equivalent emissions that captures the contrasting impacts of short- and long-lived climate pollutants

The atmospheric lifetime and radiative impacts of different climate pollutants can both differ markedly, so metrics that equate emissions using a single scaling factor, such as the 100-year Global Warming Potential (GWP100), can be misleading. An alternative approach is to report emissions as ‘warming-equivalents’ that result in similar warming impacts without requiring a like-for-like weighting per emission. GWP*, an alternative application of GWPs where the CO2-equivalence of short-lived climate pollutant emissions is predominantly determined by changes in their emission rate, provides a straightforward means of generating warming-equivalent emissions. In this letter we illustrate the contrasting climate impacts resulting from emissions of methane, a short-lived greenhouse gas, and CO2, and compare GWP100 and GWP* CO2-equivalents for a number of simple emissions scenarios. We demonstrate that GWP* provides a useful indication of warming, while conventional application of GWP100 falls short in many scenarios and particularly when methane emissions are stable or declining, with important implications for how we consider ‘zero emission’ or ‘climate neutral’ targets for sectors emitting different compositions of gases. We then illustrate how GWP* can provide an improved means of assessing alternative mitigation strategies. GWP* allows warming-equivalent emissions to be calculated directly from CO2-equivalent emissions reported using GWP100, consistent with the Paris Rulebook agreed by the UNFCCC, on condition that short-lived and cumulative climate pollutants are aggregated separately, which is essential for transparency. It provides a direct link between emissions and anticipated warming impacts, supporting stocktakes of progress towards a long-term temperature goal and compatible with cumulative emissions budgets.

The costs of achieving climate targets and the sources of uncertainty

Effective climate policy requires information from various scientific disciplines. Here, we construct a metamodel from climate and integrated assessment models that assesses the emissions budget, costs and uncertainty sources of achieving temperature targets. By calibrating to the model-based literature range, the metamodel goes beyond the parametric uncertainty of individual models. The resulting median estimates for the cumulative abatement costs (at 5% discount rate) for 2 °C and 1.5 °C targets are around US$15 trillion and US$30 trillion, but estimates vary over a wide range (US$10–100 trillion for the 1.5 °C target). The sources determining this uncertainty depend on the climate target stringency. Climate system uncertainty dominates at high warming levels, but uncertainty in emissions reductions costs dominates for the Paris Agreement targets. In fact, costs differences between different socio-economic development paths can be larger than the difference in median estimates for the 2 °C and 1.5 °C targets. This simple metamodel helps to explore implications of scenario uncertainty and identify research priorities. Costs of achieving climate targets are uncertain. A metamodel estimates the median costs of limiting warming to 2 °C and 1.5 °C to be US$15 trillion and US$30 trillion. Uncertainty in emissions reductions costs dominates at these levels; climate system uncertainty dominates at higher warming levels.

Waste timber pyrolysis in a medium-scale unit: Emission budgets and biochar quality

Pyrolysis of organic waste or woody materials yields a stable carbonaceous product that can be mixed into soil and is often termed “biochar”. During pyrolysis carbon-containing gases are emitted, mainly volatile organic carbon species, carbon monoxide and aerosols. In modern pyrolysis units, gases are after-combusted, which reduces emissions substantially. However, emission data for medium- to large-scale pyrolysis units are scant, both regarding gases, aerosols, heavy metals and polycyclic aromatic hydrocarbons (PAH).Making biochar from lightly contaminated waste timber (WT) is a promising waste handling option as it results in the potential valorization of such residues into e.g. sorbents for contaminant stabilization. For this process to be environmentally sustainable, emissions during the process need to be low and the resulting biochar of sufficient quality. To investigate both issues, we pyrolyzed three batches of WT and one reference batch of clean wood/leaves in a representative medium-scale pyrolysis unit (Pyreg-500, 750 t/year) with after-combustion of the pyrolysis gases, and measured the gas, aerosol, metal and PAH emissions, as well as the characteristics and contamination levels of the resulting biochar, including contaminant leaching.Mean emission factors for the WT were (g/kg biochar); CO = 7 ± 2, non-methane volatile organic compounds (NMVOC) = 0.86 ± 0.14, CH4 = 0, aerosols (PM10) = 0.6 ± 0.3, total products of incomplete combustion (PIC) = 9 ± 3, PAH-16 = (2.0 ± 0.2) · 10−5, As (most abundant metal) = (2.3 ± 1.9) · 10−3 and NOX = 0.65 ± 0.10. There were no significant differences in emission factors between the pyrolysis of WT and the reference respectively, except for PM10, NMVOC, and PAH-16, which were significantly lower for WT than for the clean wood/leaves. The WT biochar did not satisfy premium or basic European Biochar Certificate criteria due to high levels of zinc and PAH. However, leachable metal contents were <0.1% of total contents. Still, use of the WT-biochar without further improvement or investigation would be limited to ex situ use, not improving soil fertility or in situ remediation.

US energy system transitions under cumulative emissions budgets

Cumulative emissions budgets are increasingly being used by decision-makers and analysts to understand emissions reductions and associated transitions in the context of long-term goals such as limiting global mean temperature increase over the century to 1.5 or 2 °C. While previous studies have explored the implications of such budgets for the global economy, few studies have conducted regional- and national-level analyses. This paper explores budgets through 2050 consistent with the 1.5 and 2 °C long-term temperature goals in the context of the USA. We employ a state-level model of the USA embedded within a global human-Earth system model (GCAM-USA) to study the implications of such budgets for the US energy system. Our results show that achieving the stringent budgets entails accelerated deployment of energy conserving technology, almost complete decarbonization of the power sector, increased electrification of buildings and industrial end-use sectors, and decarbonization of transport employing a combination of electrification and the substitution of fossil fuels for bioenergy. We also find substantial state-level differences in the relative roles of these decarbonization strategies. Furthermore, our results highlight that increased ambition in the near term will be valuable in setting the stage for smoother transformations in the future to achieve stringent budgets.

Global CO&lt;SUB align="right"&gt;2 emissions mathematical modelling to meet the 2015 Paris Agreement on Climate Change

Global carbon dioxide (CO2) emissions, consistent with the 2015 Paris Agreement, are explicitly predicted by using a mathematical approach. Optimised models could serve as control tools for the emissions to meet the climate accord. These pathways are selected among an uncountable collection of models designed with short, mid, or long smooth transition to an exponential decline. A common basis to the modelling is the remaining budget of CO2 emissions, whose estimation is explicitly determined in terms of the climate target. The graphical confrontation with UN climate simulation models; the RCPs and no- and low-overshoot 1.5°C pathways, demonstrates a mitigation ranging from moderate to high, along with a smooth similar pattern which, in the short-term, would overcome a global shortage of no-carbon energy, and in the long-term, will tolerate low emissions that could be brought to nearly zero before 2050, with no need for CO2 removal from the air.

Global CO&lt;SUB align="right"&gt;2 emissions mathematical modelling to meet the 2015 Paris Agreement on Climate Change

Global carbon dioxide (CO2) emissions, consistent with the 2015 Paris Agreement, are explicitly predicted by using a mathematical approach. Optimised models could serve as control tools for the emissions to meet the climate accord. These pathways are selected among an uncountable collection of models designed with short, mid, or long smooth transition to an exponential decline. A common basis to the modelling is the remaining budget of CO2 emissions, whose estimation is explicitly determined in terms of the climate target. The graphical confrontation with UN climate simulation models; the RCPs and no- and low-overshoot 1.5°C pathways, demonstrates a mitigation ranging from moderate to high, along with a smooth similar pattern which, in the short-term, would overcome a global shortage of no-carbon energy, and in the long-term, will tolerate low emissions that could be brought to nearly zero before 2050, with no need for CO2 removal from the air.

Understanding the Benefits from Green Areas in Rome: The Role of Evergreen and Deciduous Species in Carbon Dioxide Sequestration Capability

Urban areas are a major source of anthropogenic carbon dioxide (CO2) emissions because of road traffic and local heating with natural gas, oil or coal. Rome is among the largest European cities (129,000 ha) with a large volume of green areas (69.6% of the total Municipality area). The CO2 sequestration (CS) capability for the greenery extending for about 300 km2 inside the area delimited by the Great Ring Road (GRA) in Rome was calculated combining satellite data with CS data measured in the field. Data from Sentinel-2 were collected and the Normalized Difference Vegetation Index (NDVI) was computed on a pixel-base. Three plant classes homogeneous in terms of annual NDVI profile were identified: deciduous trees (DT), evergreen trees (ET) and meadows (M) covering an area of 14,142.027 ha within the GRA, of which M had the highest percentage (48%), followed by DT (27%) and ET (25%). CS ranged from 428,241,492.9 Tons CO2 year-1 (ET) to 263,072,460.6 Tons CO2 year-1 (M). The total CS of the greenery inside the GRA was 1049,490,355.4 Tons CO2 year-1 resulting in an annual economic value of $772,424,901.6/ha. The CO2 sequestration capability of the considered plant classes could be incorporated into the national greenhouse gas emission budget to calculate the contribution of CO2 sequestration to the economy of Rome.