Supplemental Data for Gidden et al 2025: A prudent planetary limit for geologic carbon storage

Gidden, M. ORCID: https://orcid.org/0000-0003-0687-414X & Joshi, S. (2025). Supplemental Data for Gidden et al 2025: A prudent planetary limit for geologic carbon storage. 10.5281/zenodo.15657543.

Abstract

Below are table captions used in the supplementary data of the manuscript:

Table S1. Global storage volumes considering each geospatial risk consideration layer sequentially, starting from the total global technical potential of onshore storage, offshore storage, and both combined as the global total. Summing all exclusions together results in a global planetary limit, provided at the bottom of the table. An overview of the rationale and quantifications of each limit is provided for every risk consideration. Sensitivity values are provided which estimate the difference in storage based on different assumptions compared to our main estimate for each exclusion layer relative to the previous layer in the main analysis. Exclusion layer sensitivities are described in Table S2.

Table S2. Key sensitivities applied to different exclusion layers. Each sensitivity is labeled based on its Risk Consideration, aligning with tabulated values in Table S1. Negative sensitivities result in lower estimates than the central estimates while positive sensitivities result in higher values. Where sensitivities can be binary (included or not), Y (yes) means they have been included and N (no) means they have not been included. Otherwise, numerical values are provided.

Table S3. A review of available literature which estimates either maximum injection depth, minimum injection depth, or estimates both values. Numerical values are harmonized across sources to provide consistent estimates in meters (m). The majority of the literature we assessed finds that maximal storage depth ranges from around 800-3000m. One study claimed storage depth possible in the gulf of Mexico up to 3500m, but noted that it was unclear about this range due to either pressure in the geopressure zone equilibrating with fracture pressure or loss of permeability. The maximum storage depth we could find was from the USGS which uses a boundary of 3962m based on compression requirements. Taken together, and given the large preponderance of the scientific literature, we maintain a central estimate for maximum storage depth of 2500m, but apply a range between 800m and 3500m in our primary analysis to acknowledge and show the uncertainty in this key parameter in our reported results.

Table S4. A review of countries that currently have explicit policies restricting CCS. Expert judgement is used to estimate whether such policies imply major or minor restrictions and to what degree those policies are subject to change.

Table S5. Country-resolved estimates of onshore, offshore, and total carbon storage are provided for: (1) total technical potential (i.e., without any exclusion layers applied), (2) applying all exclusion layers described in Table S1, and (3) prudent storage estimates including only basins with existing oil and gas infrastructure (i.e., in which storage properties of some part of the basin have already been assessed). We additionally provide the IPCC region in which each country is considered. Countries that do not map to IPCC region categories are included at the bottom of the list. The sum of storage potential across all countries results in the planetary limit.

Table S6. IPCC Scenario categories for the scenarios assessed in this analysis. The IPCC uses shorthand labels (e.g., C1, C2, etc.), while we use the temperature outcomes.

Table S7. A mapping table showing which countries are allocated to each IPCC macro region (so called R5 regions).

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