Climate bar code (15)
The Dutch national weather service published a very simple visual that underlines temperatures are rising. A colored bar code of average temperature per year, from 1901 to 2019.

Apparently this visualisation stems from Ed Hawkins, a climate scientist in the National Centre for Atmospheric Science (NCAS) at the University of Reading. A very powerful visualization.
The Dutch version covers roughly a century of data, on Ed Hawkins’ blog you find a visualisation of UK data that goes all the way back to 1772.