We actually had a natural experiment with this during the COVID-19 pandemic! There was a study published last week in npj Climate and Atmospheric Science that found the pandemic shutdowns in...
We actually had a natural experiment with this during the COVID-19 pandemic! There was a study published last week in npj Climate and Atmospheric Science that found the pandemic shutdowns in Southeast Asia greatly reduced the concentration of these short-lived cooling particles and resulted in increased climate warming since the concentration of long-lived greenhouse gases was minimally affected.
Abstract: Anthropogenic aerosols mask the climate warming caused by greenhouse gases (GHGs). In the absence of observational constraints, large uncertainties plague the estimates of this masking effect. Here we used the abrupt reduction in anthropogenic emissions observed during the COVID-19 societal slow-down to characterize the aerosol masking effect over South Asia. During this period, the aerosol loading decreased substantially and our observations reveal that the magnitude of this aerosol demasking corresponds to nearly three-fourths of the CO2-induced radiative forcing over South Asia. Concurrent measurements over the northern Indian Ocean unveiled a ~7% increase in the earth’s surface-reaching solar radiation (surface brightening). Aerosol-induced atmospheric solar heating decreased by ~0.4 K d−1. Our results reveal that under clear sky conditions, anthropogenic emissions over South Asia lead to nearly 1.4 W m−2 heating at the top of the atmosphere during the period March–May. A complete phase-out of today’s fossil fuel combustion to zero-emission renewables would result in rapid aerosol demasking, while the GHGs linger on.
Why do I share links to climate stuff like this? I guess to get across some of the complexity. The world is an uncontrolled experiment and pollution controls have more than one effect, which means...
Why do I share links to climate stuff like this? I guess to get across some of the complexity. The world is an uncontrolled experiment and pollution controls have more than one effect, which means there are no easy answers, even if "how about we pollute less" sounds like it should obviously be good and "climate engineering" sounds dangerous.
But these sort of decisions (what kind of pollution controls huge cargo ships have) are not really up to us anyway. Even figuring out whether a climate study is a good one is beyond my competence. So I think deciding it's Someone Else's Problem is a perfectly reasonable thing to do. (And when it comes up, support the scientists who do the hard work of figuring this stuff out.)
I think Goodhart's law that a metric that becomes a target ceases to be a good metric might apply here. I'm quite skeptical of climate engineering approaches that take an extremely dynamic...
I think Goodhart's law that a metric that becomes a target ceases to be a good metric might apply here. I'm quite skeptical of climate engineering approaches that take an extremely dynamic approach to reduce certain metrics because of the myriad of potential unintended consequences. It's probably best to get away from thinking of climate change purely in terms of global warming, since ocean acidification is quite a serious issue and warming is not itself a pure bad.
From the article: […] Apparently these pollution reductions did happen, but the results aren’t known yet.
From the article:
In effect, the shipping industry has been carrying out an unintentional experiment in climate engineering for more than a century. Global mean temperatures could be as much as 0.25 ˚C lower than they would otherwise have been, based on the mean “forcing effect” calculated by a 2009 study that pulled together other findings (see “The Growing Case for Geoengineering”). For a world struggling to keep temperatures from rising more than 2 ˚C, that’s a big helping hand.
[…]
In 2016, the UN’s International Maritime Organization announced that by 2020, international shipping vessels will have to significantly cut sulfur pollution. Specifically, ship owners must switch to fuels with no more than 0.5 percent sulfur content, down from the current 3.5 percent, or install exhaust cleaning systems that achieve the same reduction, Shell noted in a brochure for customers.
There are very good reasons to cut sulfur: it contributes to both ozone depletion and acid rain, and it can cause or exacerbate respiratory problems.
But as a 2009 paper in Environmental Science & Technology noted, limiting sulfur emissions is a double-edged sword. “Given these reductions, shipping will, relative to present-day impacts, impart a ‘double warming’ effect: one from [carbon dioxide], and one from the reduction of [sulfur dioxide],” wrote the authors. “Therefore, after some decades the net climate effect of shipping will shift from cooling to warming.”
Apparently these pollution reductions did happen, but the results aren’t known yet.
We actually had a natural experiment with this during the COVID-19 pandemic! There was a study published last week in npj Climate and Atmospheric Science that found the pandemic shutdowns in Southeast Asia greatly reduced the concentration of these short-lived cooling particles and resulted in increased climate warming since the concentration of long-lived greenhouse gases was minimally affected.
Here's a press release from an affiliated academic institution: Reduced emissions during the pandemic led to increased climate warming
Why do I share links to climate stuff like this? I guess to get across some of the complexity. The world is an uncontrolled experiment and pollution controls have more than one effect, which means there are no easy answers, even if "how about we pollute less" sounds like it should obviously be good and "climate engineering" sounds dangerous.
But these sort of decisions (what kind of pollution controls huge cargo ships have) are not really up to us anyway. Even figuring out whether a climate study is a good one is beyond my competence. So I think deciding it's Someone Else's Problem is a perfectly reasonable thing to do. (And when it comes up, support the scientists who do the hard work of figuring this stuff out.)
I think Goodhart's law that a metric that becomes a target ceases to be a good metric might apply here. I'm quite skeptical of climate engineering approaches that take an extremely dynamic approach to reduce certain metrics because of the myriad of potential unintended consequences. It's probably best to get away from thinking of climate change purely in terms of global warming, since ocean acidification is quite a serious issue and warming is not itself a pure bad.
From the article:
[…]
Apparently these pollution reductions did happen, but the results aren’t known yet.
So we're all switching to the dirtiest diesel right?
Well, acid rain is a real problem. Perhaps less of one over oceans? Depending on how far it is from land.