How Reducing Ship Pollution Accidentally Sped Up Ocean Warming

What do you do when your best efforts to protect the planet seem to do just the opposite? Hopefully, drop anchor and dive deep to figure out exactly what’s going on, then chart a new course and set sail once again. And that’s what certain climate scientists are doing right now (metaphorically, of course).

Good intentions to reduce ocean pollution

In 2020, the International Maritime Organization (IMO) implemented regulations on cargo ship fuel to reduce sulphur content from 3.5% to 0.5%. The goal? “To curb the harmful aerosol pollution released by [cargo] ships” which produce ship tracks.

Unexpected effects of sulphur content reduction

So, what happens when sulphur content is significantly reduced? Less pollution (yay!) and surprisingly, increased global temperature (darn).

One American climate scientist, James Hansen, recently published a study on the issue. He concludes that because of the reduction of ship tracks and the subsequent loss of heat radiation, more energy is being absorbed by the ocean:

  • Global warming will increase to a ”rate of at least 0.27°C per decade” – up from 0.18°C per decade prior to 2010.
  • Global temperature will reach 1.5°C higher than pre-industrial temperatures during the 2020s and 2.0°C higher by the 2050s

The solution

Hansen has proposed a three-fold solution that includes:

  • Further human intervention to manage “earth’s radiation imbalance”
  • Increased global price on greenhouse gases (such as carbon tax)
  • Cooperation between the East and West in a way that would support “developing world needs

Not exactly a walk in the park, but at least there’s hope!

The takeaway

Global temperature management is no easy task, and sometimes even our best efforts may not yield the results we’re looking for. When that happens, the best thing to do is learn from our mistakes and keep trying and pushing forward!

Dig Deeper: Read Hansen’s full study and [CBC’s summary] on what he and others are saying. Spoiler: not everyone agrees on the issue!


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