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Comment by cs702 | Hacker News Reader

A powerful example of how well-intentioned regulations -- in this case, a mandate to reduce sulfur content in ship fuel, for environmental reasons -- can lead to unintended consequences that are worse than the original problem -- in this case, the reduction in sulfur led to an increase in the rate of global warming. As the saying goes, the road to hell is paved with good intentions.

Go read the abstract and the introduction. Highly recommended!

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When I was a kid, acid rain was destroying forests and lakes in Europe and North America. It was an immediate and obvious problem with catastrophic consequences. We managed to deal with it, which is why we can now afford to think about longer-term environmental issues, such as climate change.

The problem remains in large parts of Asia, where sulfur emissions have continued rising. These emission caps are necessary. They may make climate change a more urgent problem, but that's not a valid excuse to repeal the caps.

I read somewhere that sulphur emissions over the oceans aren't really a big problem. Don't know if it just the old "the solution to pollution is dilution" or if there is something more to it.

It’s not worse than the original problem. SO2 emissions from shipping are a huge problem for human health, and are very damaging to aquatic and coastal ecosystems.

The potential heating effect from reducing atmospheric aerosols was predictable and was a foreseen consequence of this regulation that was considered at the time.

But it’s important to remember that this is a “one time bump” to global heating, not cumulative like GHG emissions. In the overall context of global heating it’s pretty insignificant in the longer term.

> “one time bump” to global heating

That's not entirely accurate. Short lived climate pollutants (SLCPs) that are being continuously emitted (e.g. SO4, NOx, contrail-cirrus) have cumulative effects. The heat trapped on earth is cumulative with a long equilibration time constant, and SO4 (not just from ships) has wiped out a huge fraction of the warming up to now.

(disclaimer that I manage a climate research group)

I think the one time bump could be a fair description in that is doesn't add to the long term warming rate in the same way GHGs do. The cumulative effect here is pretty much all realised within about 20 years (so not an instantaneous effect, but it could be considered a one time one?)

Sure, it's kind of a terminology question.

There is heat being continually trapped by the SLCP, which analogous to a one-time (large) release of CO2. The earth will warm up in response, and will keep absorbing heat from the SLCP as long as the pollutant is being emitted.

As we heat up, though, we'll radiate more heat back into space (blackbody) leading to a new equilibrium temperature (the trapped flux and outgoing flux are now both larger, but balanced).

If you think about it as heat, it's cumulative. If you think about it as temperature, it'll effectively lead to a ~fixed bump (not quite a fixed one-time bump, as the effects are not linear, but one can think of it that way).

The wording is "could lead to a doubling (or more) of the warming rate" which suggests a one-time bump to the slope and a significant long-term impact on global heating.

The wording of the article and the paper are a bit misleading here. It is definitely a one time even (although it plays out over 20 years)

The doubling of the rate of warming only applies for the first year or two. Based on this paper, over the period 2020-2030, the impact of ship fuel regulations is warming of about 0.12K. The long term temperature trend is around +0.19K over this 10 year period.

>SO2 emissions from shipping are a huge problem for human health

This is one question I have regarding stratospheric sulfide injection. What goes up must come down right? What are the population wide effects of having higher concentrations of sulfide in the atmosphere?

What exactly do you mean by "one-time bump"? You're saying that the result would only be a transient increase in global temperature?

Neal Stephenson wrote a book in 2021 aptly named "Termination Shock" where sulfur is intentionally added to the atmosphere to influence the climate.

A very good book, I highly recommend it. Once I finished it I was very interested in finding more research regarding geoengineering as a method to fight climate change. Both the good and the bad are presented in the book, hence the title.

Banning sulfur isn't "good intentions". It is a quite necessary step for protecting the environment. It is just that it for a while downplayed the severity of the climate change already happening. So of course the right step now is to intensify the fight against climate change, that is, reduce our CO2 output even quicker.

Why is banning sulfur in container ship fuel necessary for protecting the environment? It seems like it might make sense to use sulfur as an additive to fuel, if it helps reduce warming.

What do you propose? No regulations?

They weren't saying they had other suggestions or options. They just pointed out the irony of this situation.

What do you propose?

How about getting more scientific input on regulations? Wasn't the cooling effect of sulfur already well known?

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