There are lots of forces, and the feedback loops are starting to hit.
- Warming has been going on for 200 years, so we are deep into it.
- The polar ice sheet has been shrinking because it is warmer. So instead of the long summer days reflecting off the ice, they are absorbed by the ocean.
- Shipping has been eliminating sulphur from bunker fuel to reduce acid rain and smog (2020 change), and the lack of smog allows more sun to reach the earth.
The recent shock of cleaner shipping exhaust has combined with the historical warming and the feedback loops of falling ice albedo (and others) shows up in warmer water.
If I remember correctly: Ships were using a particular type of gas that was outlawed recently. Turns out it was also acting as a coolant for the atmosphere. The bad news is that global warming is further along than we expected. The good news is that we now have evidence that a global campaign for cooling the atmosphere can actually work.
Can’t find sources right now, but it was very interesting when it came out ~6 months ago.
Change in the fuels cargo ships use. Previous fuels where high in sulfur which is all kinds of nasty, but has the benefit if seeding clouds. More warming this year is due to fewer clouds, at least partially.
