DataSheet1_Social cost of carbon: A revisit from a systems analysis perspective.pdf

The social cost of carbon (SCC) is estimated by integrated assessment models (IAMs) and is widely used by government agencies to value climate policy impacts. Although there is an ongoing debate about obtained numerical estimates and related uncertainties, little attention has been paid so far to the SCC calculation method itself. This work attempts to fill the gap by providing the theoretical background and economic interpretation of the SCC calculation approach implemented in the DICE (Dynamic Integrated Climate-Economy) IAM. Our analysis indicates that the present calculation method is unable to reflect the linkages between two key IAM components—complex interconnected systems—climate and economy, both influenced by emission abatement policies. Within the modeling framework of DICE, the presently estimated SCC valuates emissions, which are beyond policy control, against consumption of products, which cannot be produced by the economy. This makes the SCC irrelevant for application in climate-economic policies and, therefore, calls for a replacement by a more appropriate indicator. An apparent SCC alternative, which can be considered for policy formulation, is the direct output of the DICE model, the socially optimal marginal abatement cost (SMAC), which corresponds to technological possibilities at the optimal level of carbon emissions abatement. In policymaking, because of the revealed SCC deficiency, great attention needs to be paid to the use of estimates obtained earlier.</p

Changes in coffee suitability in 4 coffee growing zones by 2050s.

<p>a. Mesoamerica, b.1 - b.2 South America, c.1 – c.2 Africa, d.1 – d.2 Pacific.</p

Performance of the MaxEnt model across 25 replicates: (A) AUC, and (B) maximum Cohen’s kappa.

<p>The thick black horizontal line shows the median, the box shows the quartiles and the whiskers show 5–95% of the distributions.</p

Climatic conditions at Arabica coffee locations used in the analysis.

<p>¹Coefficient of Variation</p><p>²(Mean Diurnal Range /Temperature Annual Range)* 100</p><p>³standard deviation* 100</p><p>Climatic conditions at Arabica coffee locations used in the analysis.</p

Arabica coffee locations used for the analysis.

<p>Arabica coffee locations used for the analysis.</p

Suitability change in main <i>Coffea arabica</i> growing countries by 2050s.

<p>The dot represents the mean, the line the median, and the limits of the boxes are the 0.25 and 0.75 quartiles, while the extremes are the 0.05 and the 0.95 quartiles and the dots beyond the outliers.</p

MOESM1 of Assessing the INDCs’ land use, land use change, and forest emission projections

Additional file 1. Additional material

Beyond emissions trading to a negative carbon economy: a proposed carbon removal obligation and its implementation

According to most climate mitigation scenario assessments, limiting global warming to 1.5–2°C in the long run will not be possible without the extensive deployment of carbon dioxide removal (CDR) from the atmosphere. CDR is required for drawing down and achieving net-zero CO2 emissions by mid-century. Thereafter, CO2 removals will likely need to exceed residual CO2 emissions, resulting in net negative emissions. A policy framework based on ‘carbon removal obligations’ (CROs) has been proposed to respond to concerns about the financial and fiscal viability, the lack of incentives for CDR uptake, as well as the physical and technological risks associated with any climate mitigation scenario that relies on large scale CDR. Here we propose an updated and improved CRO policy framework, consisting of two core elements: the ‘principal CRO mechanism’ obliges emitters of a tonne of CO2 to remove a tonne of CO2 at the time of maturity of the CRO. On top of this obligation, CRO holders need to pay a fee for the temporary storage of CO2 in the atmosphere. This ‘CRO pricing instrument’ is used by regulators to steer the carbon emissions and removals pathways independently. Our update suggests that markets for CDR under the CRO framework should operate independently from markets for emission reductions. We propose a blueprint for legal implementation where CROs are integrated akin to private financial borrowing and debt mechanisms. By aligning CROs with established financial systems, we leverage familiar institutional roles, seamlessly integrating climate mitigation into the core economy. The proposal applies the polluter pays principle to the costs of carbon removal from the atmosphere, whilst providing legal guarantees that the removals will materialize.By placing climate change mitigation pricing levers in the hands of the traditional managers of financial stability, that is, central banks, better account is taken of the externality of carbon emissions as part of core economic and financial management, with the corollary that climate change mitigation response management is better integrated into the economic mainstream.Establishing a standard for the creation of removal units by CDR projects facilitates a more efficient market by reducing transaction costs and enhancing price discovery.Early action by government to put in place legislative measures indicating the direction of policy, and a timetable for introducing CROs, would enhance private sector confidence and engagement in the CDR project sector. The proposal applies the polluter pays principle to the costs of carbon removal from the atmosphere, whilst providing legal guarantees that the removals will materialize. By placing climate change mitigation pricing levers in the hands of the traditional managers of financial stability, that is, central banks, better account is taken of the externality of carbon emissions as part of core economic and financial management, with the corollary that climate change mitigation response management is better integrated into the economic mainstream. Establishing a standard for the creation of removal units by CDR projects facilitates a more efficient market by reducing transaction costs and enhancing price discovery. Early action by government to put in place legislative measures indicating the direction of policy, and a timetable for introducing CROs, would enhance private sector confidence and engagement in the CDR project sector.</p

Sankey diagrams highlighting the shares of dominant soil type, the intensity of cultivation and total crop production across all foodscape classes.

Values indicate the percent of terrestrial land area, million ha and million tons respectively. Intensity group colors as in Fig 1B. See S3 Table in S1 File for a legend and crosswalk table between foodscape classes and intensity groups. Figure adapted from a version created by Nicholas Rapp for the TNC Foodscape report [77].</p

Fig 3 -

Intersection of foodscapes area with biophysical and socioeconomic risks globally (A). Shown on a bivariate scale are those foodscapes most exposed by single or multiple pressures, with darker green colours indicating a greater exposed proportion of the individual foodscape (Fig 1). Barplot highlights the average proportion of exposed foodscape to biophysical or socio-economic risks. Circular plots show cumulative exposed proportion of foodscape area by pressures separated by biophysical (B) and socio-economic risks (C).</p