Geological Net Zero and the need for disaggregated accounting for carbon sinks.

Achieving net zero global emissions of carbon dioxide (CO), with declining emissions of other greenhouse gases, is widely expected to halt global warming. CO emissions will continue to drive warming until fully balanced by active anthropogenic CO removals. For practical reasons, however, many greenhouse gas accounting systems allow some "passive" CO uptake, such as enhanced vegetation growth due to CO fertilisation, to be included as removals in the definition of net anthropogenic emissions.

National contributions to climate change due to historical emissions of carbon dioxide, methane, and nitrous oxide since 1850.

Anthropogenic emissions of carbon dioxide (CO), methane (CH) and nitrous oxide (NO) have made significant contributions to global warming since the pre-industrial period and are therefore targeted in international climate policy. There is substantial interest in tracking and apportioning national contributions to climate change and informing equitable commitments to decarbonisation. Here, we introduce a new dataset of national contributions to global warming caused by historical emissions of carbon dioxide, methane, and nitrous oxide during the years 1851-2021, which are consistent with the latest findings of the IPCC.

Methane and the Paris Agreement temperature goals.

Meeting the Paris Agreement temperature goal necessitates limiting methane (CH)-induced warming, in addition to achieving net-zero or (net-negative) carbon dioxide (CO) emissions. In our model, for the median 1.5°C scenario between 2020 and 2050, CH mitigation lowers temperatures by 0.

Emerging reporting and verification needs under the Paris Agreement: How can the research community effectively contribute?

Greenhouse gas (GHG) emission inventories represent the link between national and international political actions on climate change, and climate and environmental sciences. Inventory agencies need to include, in national GHG inventories, emission and removal estimates based on scientific data following specific reporting guidance under the United Nation Framework Convention on Climate Change (UNFCCC) and the Paris Agreement, using the methodologies defined in the Intergovernmental Panel on Climate Change (IPCC) Guidelines. Often however, research communities and inventory agencies have approached the problem of climate change from different angles and by using terminologies, metrics, rules and approaches that do not always match.

Where is the EU headed given its current climate policy? A stakeholder-driven model inter-comparison.

Recent calls to do climate policy research with, rather than for, stakeholders have been answered in non-modelling science. Notwithstanding progress in modelling literature, however, very little of the scenario space traces back to what stakeholders are ultimately concerned about. With a suite of eleven integrated assessment, energy system and sectoral models, we carry out a model inter-comparison for the EU, the scenario logic and research questions of which have been formulated based on stakeholders' concerns.

Challenges in the harmonisation of global integrated assessment models: A comprehensive methodology to reduce model response heterogeneity.

Harmonisation sets the ground to a solid inter-comparison of integrated assessment models. A clear and transparent harmonisation process promotes a consistent interpretation of the modelling outcomes divergences and, reducing the model variance, is instrumental to the use of integrated assessment models to support policy decision-making. Despite its crucial role for climate economic policies, the definition of a comprehensive harmonisation methodology for integrated assessment modelling remains an open challenge for the scientific community.

Gridded fossil CO emissions and related O combustion consistent with national inventories 1959-2018.

Quantification of CO fluxes at the Earth's surface is required to evaluate the causes and drivers of observed increases in atmospheric CO concentrations. Atmospheric inversion models disaggregate observed variations in atmospheric CO concentration to variability in CO emissions and sinks. They require prior constraints fossil CO emissions.

A comprehensive quantification of global nitrous oxide sources and sinks.

Nitrous oxide (NO), like carbon dioxide, is a long-lived greenhouse gas that accumulates in the atmosphere. Over the past 150 years, increasing atmospheric NO concentrations have contributed to stratospheric ozone depletion and climate change, with the current rate of increase estimated at 2 per cent per decade. Existing national inventories do not provide a full picture of NO emissions, owing to their omission of natural sources and limitations in methodology for attributing anthropogenic sources.

Empirical estimates of regional carbon budgets imply reduced global soil heterotrophic respiration.

Resolving regional carbon budgets is critical for informing land-based mitigation policy. For nine regions covering nearly the whole globe, we collected inventory estimates of carbon-stock changes complemented by satellite estimates of biomass changes where inventory data are missing. The net land-atmospheric carbon exchange (NEE) was calculated by taking the sum of the carbon-stock change and lateral carbon fluxes from crop and wood trade, and riverine-carbon export to the ocean.

Comment on "The global tree restoration potential".

Bastin (Reports, 5 July 2019, p. 76) claim that global tree restoration is the most effective climate change solution to date, with a reported carbon storage potential of 205 gigatonnes of carbon. However, this estimate and its implications for climate mitigation are inconsistent with the dynamics of the global carbon cycle and its response to anthropogenic carbon dioxide emissions.

Structural Changes in Provincial Emission Transfers within China.

Chinese provinces ultimately implement China's national climate policies. In the 2000s, there were unbalanced emission transfers (emissions produced in one region but consumed in other regions) between China's well- and less-developed regions, mainly related to demand in the well-developed eastern provinces. In the past decade, the plateau in China's exported emissions and changes in its industrial structure suggest that the features of the provincial emission transfers could have changed.

Reducing uncertainties in decadal variability of the global carbon budget with multiple datasets.

Conventional calculations of the global carbon budget infer the land sink as a residual between emissions, atmospheric accumulation, and the ocean sink. Thus, the land sink accumulates the errors from the other flux terms and bears the largest uncertainty. Here, we present a Bayesian fusion approach that combines multiple observations in different carbon reservoirs to optimize the land (B) and ocean (O) carbon sinks, land use change emissions (L), and indirectly fossil fuel emissions (F) from 1980 to 2014.

Reduced carbon emission estimates from fossil fuel combustion and cement production in China.

Nearly three-quarters of the growth in global carbon emissions from the burning of fossil fuels and cement production between 2010 and 2012 occurred in China. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China's total fossil fuel carbon emissions in 2008 differ by 0.3 gigatonnes of carbon, or 15 per cent.

Climate warming feedback from mountain birch forest expansion: reduced albedo dominates carbon uptake.

Expanding high-elevation and high-latitude forest has contrasting climate feedbacks through carbon sequestration (cooling) and reduced surface reflectance (warming), which are yet poorly quantified. Here, we present an empirically based projection of mountain birch forest expansion in south-central Norway under climate change and absence of land use. Climate effects of carbon sequestration and albedo change are compared using four emission metrics.

Frameworks for comparing emissions associated with production, consumption, and international trade.

While the problem of climate change is being perceived as increasingly urgent, decision-makers struggle to agree on the distribution of responsibility across countries. In particular, representatives from countries hosting emissions-intensive exporting industries have argued that the importers of emissions-intensive goods should bear the responsibility, and ensuing penalties. Indeed, international trade and carbon leakage appear to play an increasingly important role in the carbon emissions debate.

Mapping flows of embodied emissions in the global production system.

Environmentally extended multiregional input-output (MRIO) analysis can be used to investigate final production and consumption attributions of emissions. As the distinction between the two attributions has been brought to the attention of policy-makers, there is an ever greater need to understand how and why they differ, by analyzing the connections between production and consumption activities. Seeking to meet this need, we present an approach for mapping flows of embodied emissions through a Leontief production system.

The supply chain of CO2 emissions.

CO(2) emissions from the burning of fossil fuels are conventionally attributed to the country where the emissions are produced (i.e., where the fuels are burned).

Alternative "global warming" metrics in life cycle assessment: a case study with existing transportation data.

The Life Cycle Assessment (LCA) impact category "global warming" compares emissions of long-lived greenhouse gases (LLGHGs) using Global Warming Potential (GWP) with a 100-year time-horizon as specified in the Kyoto Protocol. Two weaknesses of this approach are (1) the exclusion of short-lived climate forcers (SLCFs) and biophysical factors despite their established importance, and (2) the use of a particular emission metric (GWP) with a choice of specific time-horizons (20, 100, and 500 years). The GWP and the three time-horizons were based on an illustrative example with value judgments and vague interpretations.