Take on a podcast episode from The CDR Policy Scoop, originally published Sun, 02 Au. Listen: https://shows.acast.com/the-cdr-policy-scoop/episodes/inside-the-framework-for-residual-emissions-with-injy-johnst

TL;DR

  • Residual emissions has no shared definition — the term drifted from IPCC modeling into corporate net-zero plans without translation. Useful framing.
  • Johnstone insists “hard-to-abate” (technological limit) ≠ “residual” (broader, includes demand-side and normative choices). Overdue distinction.
  • Proposes three buckets: near-term abatable now, medium-term (2040) plausible tech, long-term (2050) speculative — with 5-year reassessment.
  • Warns the medium-term bucket is where optimism bias silently shrinks today’s carbon removal (CDR) demand. This is the real signal.
  • Compares SBTi v2 and draft ISO net-zero standards: ISO handles residuals with more specificity, SBTi punts implementation into future decades.

Sebastian Manhart and Eve Tamme host Dr. Injy Johnstone (Oxford Net Zero) to unpack her Drax-funded report What Are Residual Emissions? — a term everyone uses in net-zero pathways and almost nobody defines the same way. The episode is a 30-minute methodological conversation, not a market update.

The load-bearing insight for CDR practitioners is Sebastian’s point about the medium-term bucket. If a corporate (or country) assumes aggressively that 2040-era technology will abate a category currently classified as residual, that assumption directly reduces the CDR volume they’d commit to procuring today. Johnstone’s answer — that near, medium and long-term buckets have to be assessed simultaneously and revisited on a 5-year cycle — is the right process response, but she’s honest that transparency about which assumptions moved an emission from “residual” to “future-abatable” is largely absent from current disclosures. This is where the CDR gap gets quietly widened.

The other useful thread is her read on standards. Johnstone argues SBTi’s v2 net-zero standard still leaves the substantive residual-emissions work to future decades, while the draft ISO net-zero standard actually requires a plan, a feasibility test, and recognizes pathway diversity. That’s a non-trivial claim — if ISO lands close to the draft, it becomes the more demanding instrument for residual-emissions accounting, which matters for anyone modeling neutralization demand. Her framing that residual emissions embed normative choices (“how many flights in 2050, what diets”) is worth sitting with: those choices are already baked into today’s pathways, just not surfaced.

For adjacent context, this pairs with the Scoop’s earlier Harry Smith episode on long-term strategies (same problem, government side: wildly divergent residual-emissions assumptions inside NDCs and LTSs), and with the ongoing SBTi v2 consultation debate that’s been running through 2026. Anyone building a corporate CDR offtake thesis needs a view on how buyers will size their residual-emissions volume — the report Johnstone co-authored is one of the few attempts to give that exercise structure. She flagged forthcoming academic publications extending the framework.

Useful for: CDR commercial teams sizing long-dated demand, policy folks tracking SBTi v2 and ISO 14060-series developments, and measurement, reporting, and verification (MRV) people who need to explain to a buyer why the “residual” number on their net-zero plan is a choice, not a measurement.