September 2, 2026 — The Intergovernmental Panel on Climate Change has named UC Santa Barbara assistant teaching professor Iris Holzer as a lead author on its next Methodology Report on Carbon Dioxide Removal Technologies, Carbon Capture, Utilization, and Storage. The document underpins National Greenhouse Gas Inventory reporting for 194 member countries.

Holzer, a soil scientist who joined UCSB in 2024, will help rewrite the accounting guidance for terrestrial carbon capture, storage and utilization — sections covering biochar, wetland carbon storage, carbon mineralization and enhanced rock weathering.

"The IPCC guidance creates the starting point for a lot of other conversations about carbon accounting and national research priorities around carbon sources and sinks," Holzer said.

What does the report cover?

The Methodology Report is the technical companion to the IPCC's broader climate assessments, the first of which appeared in 1990. Updated every five to seven years, it provides tiered guidance — coarse, sector-level estimates through refined facility and region-specific calculations — based on each country's data resources.

The 2026 iteration zeroes in on carbon dioxide removal (CDR) and carbon capture, utilization and storage (CCUS), the engineered and nature-based pathways for pulling CO2 from the atmosphere and locking it away. Holzer framed CDR plainly: "Carbon dioxide removal is taking CO2 out of the atmosphere and putting it somewhere else."

Captured carbon can be stored underground, sequestered in the deep sea or converted into products ranging from cling wrap to concrete bulking pellets. The current accounting frameworks predate commercial CDR and CCUS deployment at scale.

"Both nature-based and technological approaches to removing CO2 from the atmosphere are evolving super rapidly," Holzer said. "So the member countries asked for an updated report."

Where does Holzer's expertise apply?

Holzer's research centers on soil carbon storage and enhanced rock weathering, a technique that accelerates natural geochemical reactions to sequester CO2 in mineral form. Her lead-author role will shape the report's guidance on estimating soil organic carbon and below-ground fluxes.

The methodology offers tiered granularity. When the United States was still publishing a national inventory, it used sophisticated models that incorporated soil characteristics, land-use and weather data, plus direct observations, to track organic carbon stored in soil.

"A country with less of their own data available might use default values that are provided in the methodology report," Holzer said.

She plans to build a younger, more diverse author team. "There's quite a few people who've been on these reports since the beginning," she said. "And I think they want to cultivate a new generation of authors."

The report covers terrestrial sources, sinks and uses only. Ocean-based carbon accounting falls under separate international treaties and protocols, Holzer noted.

What does the US withdrawal change?

U.S. government participation in the IPCC has ended, but American scientists continue to contribute through a consortium hosted by the American Geophysical Union. Holzer, one of the U.S.-based authors, acknowledged the unusual arrangement.

"It's a really strange position because there's a lot of scientific expertise in the United States," she said, "but our country as a whole has taken a backseat in this conversation and this process."

"Participating is a way to say that, even if the country has stepped back from this, we can still contribute to this on an international scale, among the 194 other countries that have placed a priority on understanding their contributions to global climate change," Holzer added.

What is the next IPCC milestone?

The Methodology Report enters a multi-year drafting cycle under IPCC's working group structure. Final publication will set the technical baseline that national inventory compilers and CCUS project developers use to credit removals and report emissions.

Holzer closed with a warning aimed at the practitioners who will rely on the document: "Data alone are not going to change anything. We have to figure out how to go from knowledge to some kind of actionable change."

The next regulatory checkpoint is the report's draft scoping outline, which IPCC member governments are scheduled to review before the methodology text is finalized.