Charted: Why coal is such a big deal at COP26

The chart above illustrates why the new pledge by dozens of countries to phase out coal in the 2030s and 2040s at the COP26 summit has been one of the most attention-grabbing developments this week.

"Seeing major coal-burning economies such as Viet Nam, Indonesia, South Korea and Ukraine commit to a coal exit genuinely is the progress we need to see," said Pauline Heinrichs, of the climate think tank E3G, in a statement. (Indonesia's endorsement was partial, however.)

Yes, but: China, which accounts for about half of global coal demand, did not sign-on. Nor did India, another major user.

• The U.S. didn't either, though Alok Sharma, the U.K. official presiding over COP26, noted the U.S. has endorsed decarbonized power in the 2030s via a G7 statement in May.