In 2002, then-Secretary of Defense Donald Rumsfeld famously answered a question about combat intelligence with a reference to “unknown unknowns”: that is, things that are not merely unknown, but that we have not even thought to consider, perhaps because they’re things that have never happened before or that have not had previous importance.

Some, at that time, derided Rumsfeld’s phrase as if it were a novel (or even nonsensical) coinage, but the term had been in published use since at least as early as 1968 – notably in aerospace and other military domains, with “unk-unks” even achieving the status of a common informal contraction. More than half a century later, it seems to me that much of our conversation about abrupt climate change has to include our recognizing, investigating, measuring, modeling, and forecasting unk-unk measurements and processes. I suspect that future notes here will include many examples.

This week’s note, though, looks at something that might seem actually contradictory, what Slavoj Zizek in 2004 called “unknown knowns.” Excuse me, isn’t that an obvious oxymoron? It’s not, because what Zizek meant was that there are “disavowed beliefs we pretend not to know about.” These are “unknown” knowns in the sense that we are refusing to acknowledge the knowledge. Perhaps we don’t want to admit its truth because it’s a result of past errors; perhaps we don’t want to be burdened with responsibility to do something about that truth.

Al Gore called such truths “inconvenient,” but we seem now to be escalating things: not merely neglecting to address what we don’t want to acknowledge, but actively corrupting measurements and abandoning records of events and trends. We are committing governmental and institutional acts of un-knowing.

First example, and the item in my news feed that got me thinking about this, is the altered approach to carbon accounting that appears to be embedded in China’s February 2026 “Statistical Communique.” A footnote in that document now refers to “carbon dioxide emissions in the process of energy activities and industrial production [my italics],” which (as Al Gore might say) conveniently seems as if it may be newly excluding non-energy sources of emission such as production of cement or incineration of plastics.

“On paper, the change in the carbon-intensity metric effectively halves the rate of growth in China’s CO₂ emissions over the past five years,” estimated analyst Lauri Myllyvirta on Carbon Brief last week. This is not a minor adjustment, but rather a change that creates what Myllyvirta calls a “Germany-sized” reduction of China’s self-reported CO₂ footprint. TL;DR points include,

• The change in the definition of carbon intensity has the effect of weakening China’s climate targets and introducing more uncertainty into tracking progress
• On the basis of China’s new numbers, it will require less effort to hit the 2030 target for a 65% reduction in carbon intensity on 2005 levels, as per China’s Paris pledge
• This target can now be met even if CO₂ emissions go up between 2025 and 2030, whereas the previous metric would have required a reduction

This one example already felt like a topic for this week, but then I encountered another demonstration of willfully choosing not to know: the International Disaster Database, known as EM-DAT, has primarily been funded by the U.S. Agency for International Development which is no longer providing that support. Analyst Antoine Soetewey summarizes the problem as follows:

EM-DAT’s value is not just in the quantity of records. It lies in the rigour and consistency of its methodology over time and across countries. That is exactly what makes it irreplaceable. In a world awash with data, curated and quality-controlled datasets of this kind are rare. If EM-DAT were to close, the result would not be a smooth substitution. It would be fragmentation, proprietary data silos, and reduced access, particularly for lower-income countries that are already under-represented in global evidence.

An open letter on this situation makes the following assessment:

In an era of intensifying climate extremes, cascading risks, and compounding crises, reliable data are not a luxury. They are the infrastructure for informed decision-making. Disaster risk reduction, early warning systems, anticipatory action, and climate adaptation all require credible historical baselines. We cannot measure progress against the Sendai Framework for Disaster Risk Reduction, the Sustainable Development Goals, or the Paris Agreement without consistent data on disaster impacts. We cannot credibly argue for risk-informed development if the underlying evidence base is fragmented.

Third example: the U.S. National Centers for Environmental Information announced in May that its “Billion Dollar Weather and Climate Disasters” product “will be retired, with no updates beyond calendar year 2024.” One climate risk analyst opined that “What makes this resource uniquely valuable is not just its standardized methodology across decades, but the fact that it draws from proprietary and non-public data sources (such as reinsurance loss estimates, localized government reports, and private claims databases) that are otherwise inaccessible to most researchers.”

He added that “Without it, replicating or extending damage trend analyses, especially at regional scales or across hazard types, is nearly impossible without significant funding or institutional access to commercial catastrophe models.” Something that we usefully knew, through 2024, is being chosen to be less knowable.

There is an Arabic proverb on the subject of knowledge, and of knowledge about one’s knowledge, that is said to go like this:

People are of four types:

• Those who know, and know that they know – they are scholars, so follow them
• Those who know, but do not know that they know – they are asleep, so awaken them
• Those who do not know, but know that they do not know – they are seeking guidance, so guide them
• Those who do not know, and do not know that they do not know – they are dolts, so shun them

I don’t know what the proverbist would say about “Those who know, but do not admit to that knowledge or take up its responsibilities” – but “awaken” or “guide” may not be sufficiently vigorous verbs, while “shun” is not an option as long as we just have one planet. Suggestions welcome.