2025 trends: aerosols, oil demand, and carbon removal

The aerosol segment is the one with real physical stakes. Bullard walks through a waterfall chart, credited to Zeke Hausfather writing at The Climate Brink, that decomposes present-day warming: carbon dioxide, other greenhouse gases, methane, other human causes and a little natural variation add to nearly 1.9 degrees Celsius, and then 175 years of aerosol emissions subtract 0.57 degrees of that. The aerosols are mostly sulfur dioxide from burning coal in land-based power plants, plus marine particulates from ships burning bunker fuel, which is why the effect is strongest over heavily trafficked water such as the North Atlantic. Aerosols have no warming effect at all, only a cooling one, so cleaning them up does not slow warming, it unmasks it, and it does so most over the places where sunlight had been blocked. Bullard’s sharpest framing is that this is the geoengineering proposal run in reverse. Injecting sulfur dioxide high into the atmosphere to cut incoming sunlight, what Oliver Morton calls veil making, is exactly what we were doing accidentally and have now stopped.

The attribution inside that story is where the episode corrects a common belief, and it matters for how the note should be read. The marine fuel rules are the part that gets talked about, but Bullard’s charts put China’s sulfur dioxide reduction well ahead of it, and Kann says so explicitly while comparing the two series. China’s decline did not come from moving off coal; it came from scrubbing, the same control technology North America installed in the 1970s and 1980s, applied to power generation, industrial coal use and oil combustion. Both speakers then explain why the larger cause is the less discussed one: air quality benefits are felt locally, so the marine improvement is visible in port cities like Newark and Rotterdam while China’s much larger improvement is visible mainly in China and the North Pacific. Bullard adds an institutional point rather than a scientific one. None of this was mysterious to atmospheric scientists; the climate consequence simply sat outside the frame of the International Maritime Organization’s negotiations over sulfur limits, because the people who study solar geoengineering and the people who regulate shipping fuel do not talk to each other.

The energy-flows segment turns on a similar gap between the headline and the number. Bullard notes that the United States now exports about as much energy on a trailing twelve-month basis as it imported in the early 1980s, measured in primary energy terms rather than in specific fuels, and he stresses that “net” is the operative word, since the country still imports millions of barrels of oil a day for structural refining reasons. Given that the US is the largest oil producer, by a wide margin the largest gas producer, the largest exporter of liquefied natural gas and adding zero-carbon domestic electricity, he finds the political slogan of energy dominance a curiosity: he does not know what more would be required to qualify. The pointed version of his question is what state action could make the country export or produce materially more, given that the US, with Canada, is the only very large producer that is a full market economy where the state does not decide how much gets drilled or shipped, a claim he immediately qualifies as not entirely true. China is the mirror image. It passed Japan, then the US, then the European Union to become the world’s largest oil importer, taking in more than 13 million barrels a day as of 2023, and yet its apparent demand, a figure derived from refinery runs, looks to have peaked in 2023, with data published the previous morning showing the big refiners’ throughput down slightly year on year. Industry and transport both contribute, transport increasingly including heavy duty vehicles rather than only cars, and some refined products peaked years earlier.

The segment on sustainable investing runs on the same gap between what is said and what is happening. Bullard’s running count of Larry Fink’s annual BlackRock letter shows sustainability and climate mentioned about 45 times combined in 2020 and five times in the letter published in the spring of the year before recording, with ESG itself all but vanished. Yet assets under management in environmental, social and governance funds are approaching 5%, having surged in 2020 and 2021 and grown slowly rather than reversed since. Bullard’s explanation is that American politics around the label has decoupled from investment performance, that European institutional investors retain appetite for structural reasons, and that the performance story, including a clean energy exchange-traded fund doing poorly, is usually left out of the political version. When Kann proposes that climate people should sever climate from the ESG umbrella, Bullard reframes rather than agrees: these are a set of issues, useful as a screen or filter on institutional investment, and not a set of drivers or an investment case. The label says nothing about what a company actually supplies to the market. Carbon removal shows a different shape, a 2021 bubble deflating on both sides at once. Roughly 500 carbon dioxide removal startups exist and almost 80 were founded in 2021 alone, which Bullard files under a deck section joking that some things are a 2021 thing. Voluntary carbon credit issuance followed the same curve, more than 300 million credits and more than 2.1 billion in transaction value in 2021, falling to roughly 150 million last year. Both men read the deflation as at least partly healthy, and Kann expects a genuine shakeout, because the number of startups grew and the buyer pool did not.