Imagine you have a big blanket (the clouds) that keeps the Earth cool by blocking some of the sun. When ships burn dirty fuel, it makes the blanket thicker, which is good for keeping the Earth cooler. But in 2020, ships started using cleaner fuel, so the blanket got thinner. This made the Earth feel warmer because more sun could get through. So, even though cleaner fuel is good for our air, it made the Earth warmer by accident.
Explain like I'm 5:
Imagine you have a big blanket (the clouds) that keeps the Earth cool by blocking some of the sun. When ships burn dirty fuel, it makes the blanket thicker, which is good for keeping the Earth cooler. But in 2020, ships started using cleaner fuel, so the blanket got thinner. This made the Earth feel warmer because more sun could get through. So, even though cleaner fuel is good for our air, it made the Earth warmer by accident.