The 1st of January 2020 is when the new international shipping regulation comes into force which will cut the air pollution from ships. The fuel must now be refined to remove basic impurities before it is used by ships. This is good news.
The bad news is that it has taken so long to achieve, if indeed it is successfully implemented. If the UN funded International Maritime Organisation had sufficient authority then the world could have passed this milestone in cleaner fuel for ships decades ago. Humanity cannot afford to waste time, we should agree on a global system of co-operation.