4/ The captain doesn’t know the iceberg’s depth or how the hull would react. Similarly, temperature projections are uncertain. But uncertainty isn’t ignorance and shouldn’t excuse inaction. It should drive us to act on what we can control: the ship’s turning radius—our greenhouse gas emissions.

3/ The ship hasn’t completed its turn (orange: emissions still rising), but change has begun. Compared to ten years ago, the worst risks (red) are less likely. Recent pledges lower risk further (yellow), yet we remain in dangerous waters. To reach safer zones, the turn must accelerate (green).

2/ Imagine a transatlantic liner at full speed: that’s the global economy. Emissions set its course. Scientists spot a huge iceberg and raise the alarm. After long discussions, just like at climate conferences, the danger is acknowledged and the collective decision is made to steer the ship ...

thanks to the great team of co-authors, including Michel den Elzen, Zuelclady M.F. Araujo Gutierrez, Will Lamb, Nicklas Forsell, Joana B. Melo, Simone Rossi, Malte Meinshausen, Sandro Federici, Matthew GIDDEN, Kimon Keramidas, Anu Korosuo

🤔 However, land use remains a blind spot in tracking progress under the #ParisAgreement, mainly due to inconsistencies between global models and country-reported data.

💡 It is crucial that future #GlobalStocktakes include comparisons between modeled and country-provided net land-use emissions.

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Thanks to the stellar co-authors, including @glenpeters.bsky.social , @pepcanadell.bsky.social , @gidden.bsky.social and others, and to all participants of the IPCC Expert Meeting.

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This is relevant for forest-rich nations, where “natural” sinks often play a major role in net-zero pledges.
Policymakers need to grasp these implications and adjust their climate ambition accordingly

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We also urge the scientific community to generate these inventory-aligned estimates and scenarios, and to explore the implications.

Key takeaways: under inventory definitions, the remaining carbon budget is smaller—and reaching net-zero CO₂ alone is not enough to stop warming.

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Drawing on prior studies and IPCC Expert Meetings, the IPCC has recently decided that its 7th Assessment Report will present land-use CO₂ estimates and scenarios that align with national inventory definitions.

Our Comment explains why this is a crucial step forward.

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These differing definitions are like two languages: each valid in its own context, but hard to compare without proper translation.

Reconciling them is key for aligning global models, national inventories, and Earth observation — ultimately building trust in land-use emission estimates.

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Climate science and national reporting use different definitions for anthropogenic land-use CO₂ fluxes.

This disconnect has led to a 7 billion-tonne annual gap in CO₂ estimates from land use—equivalent to 20% of global fossil CO₂ emissions—causing confusion among scientists and policymakers

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