It may be because I've seen a lot of visualizations in the past decades but, even if I liked the map a lot, I didn't find it that impressive or insightful. It's a bit like a population map, after all, although I'll admit it helps bring attention to the story.
I was more interested in the variation of emissions and their sources. Fortunately, Nadja Popovich and Denise Lu, the authors, also cover that in the graphs that follow the map. There's a lot of attention to detail in the design of these. Notice the annotations and the careful use of color:
