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Trace the Information: Did a reduction in ship pollution speed up climate change?

SKILL: Trace the Information

DIFFICULTY: Challenging

SUBJECT(S): Climate change

A Reddit post claims that the reduction of shipping pollution has, ironically, caused a global temperature increase. Students will trace the information back to the original source to find that while scientists have proposed the idea, the science is not settled.


The sulphur in commercial ship exhaust contributes to the formation of marine clouds, or ship tracks, that radiate heat back out into space. To curb this harmful pollution, regulations were imposed in 2020 to reduce sulfur content in fuel. 

However, some scientists have suggested that the reduction in marine clouds has had an unexpected effect: with fewer ship tracks, more heat is absorbed into the oceans, potentially accelerating global warming.

About the Example

A post in the subreddit r/Irony claims, “Ironic, reduction of pollution causes an acceleration of global destruction. It’s like rain on your wedding day.” The comment is accompanied by what appears to be a headline saying, “[s]cientists warn Earth is warming faster than expected — due to reduction in ship pollution.” 

While the information in the Reddit post seemingly goes against the common knowledge that pollution is a driver of climate change, the Reddit user also linked to an article from the CBC, which can provide us with more information. 

We can use the click through and find skill to trace this information back to the CBC article reporting on the original scientific study to gain key context about the claim. 

The CBC article tells us that while a study by climate scientists does indeed suggest that a reduction of marine clouds from shipping emissions has allowed more heat to be absorbed in the oceans, the science isn’t nearly as settled as the headline suggests. In fact, other scientists have called the study’s results into question, and the study’s authors themselves have noted a need for more research. 

That’s not to say that the study is completely wrong. But it’s important to recognize that headlines can often make it seem like scientific results are much more agreed upon than they actually are, especially when those results are new and unusual.


  1. Show students the Reddit post and have them summarize the claim. Fill in any gaps in their knowledge about global warming.
  2. Have students click on the article linked in the post. Guiding questions:
    • What source does the Reddit post link to? Is it a reliable source of information on climate change?
    • Was the story distorted when it was re-shared on Reddit? Explain your reasoning.
    • What additional context did you learn by clicking through the attribution link to the CBC article? Why is this context important?

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