Clean Fuel Laws May Have Caused This Year's Sudden Climate Change
But this isn't what you think.

Over the past few years, we have seen climate change really start to bite. Deadly cold snaps, crop-ruining droughts, heatwaves that pushed entire countries to the brink and record-setting global average temperatures. This sudden global warming is utterly unprecedented and far more extreme than any of our climate models ever predicted. So what’s going on? Well, a few studies have found that a recent change to shipping fuel standards to clean up the cargo industry might be to blame. However, this climate rabbit hole goes far deeper than just ships, as this could not only be the beginning of yet more sudden climate change but also a route to genuinely safe and effective geoengineering.
When I say sudden global warming over the past few years, I mean it. We haven’t just had bad luck with some extreme weather events. Take the graph below that has gone viral, shared by climate scientists and science communicators alike. This really is the year when climate change started to bite. But why?
This all starts with the International Maritime Organisation (IMO). They are responsible for setting international standards for all types of vessels and regulating the marine industry. One of their greatest challenges is reducing the environmental impact of cargo ships. You see, these oceanic leviathans operate on razor-thin profit margins, so every cost-saving measure they can take makes a vast difference. As such, for decades, they have used bunker fuel, also known as Heavy Fuel Oil, to power their gigantic combustion engines. This fuel is effectively what is left after a refinery has extracted all the kerosene, diesel, petrol, bitumen and other useful elements from crude oil. HFO is really dirty, as all the impurities in the crude oil are effectively concentrated into it during the refining process. This, combined with its less-than-ideal burning dynamics, makes it a filthy and inefficient fuel to use in combustion engines. But as no one else wants it, HFO is incredibly cheap!
One of the main impurities in HFO is sulphur. When burnt, this creates sulphates and sulphur particulates, and once in the atmosphere, they create ecosystem-wrecking acid rain and can severely irritate and damage the respiratory systems of animals. So in 2020, the IMO introduced a new regulation that ensured cargo ships could only use low-sulphur fuels to reduce these emissions and take a small baby step towards a sustainable shipping industry.
While this new regulation is a step in the right direction, mounting evidence indicates that it caused the sudden global warming we have seen recently. Let me explain.
Those sulphate emissions temporarily cool the climate. You see, climate change is driven by the increase in greenhouse gases in the atmosphere. These gases are transparent to visible light but absorb infrared light. This means the Sun’s light (and energy) passes through the atmosphere mostly unstopped. The ground then absorbs some of this energy and heats up. As it heats up, it gives off black body radiation in the form of infrared light (which is what thermal imaging sees). This infrared light is then absorbed by the greenhouse gasses in the atmosphere, which heats the gas and the overall atmosphere up. So effective, the more greenhouse gases in the atmosphere, the more of the Sun’s energy is trapped in the atmosphere.
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