Markey hands down. Nothing against Kerry it's just that Markey is more progressive, he helped author the GND.
The Green New Deal is like six pages. It's pretty sad if, after decades in public life, the main thing going for the guy is that he "helped" author a few pages of non-binding recommendations, non of which were original or innovative in any way, and which continue to be the laughingstock of DC.
John Kerry wrote the Paris Agreement and got 195 countries to sign on. In the real world, that's a monumental achievement. But on Atlas, this pales next to Unstoppable Climate Titan Ed Markey, who helped a House freshman sabotage the climate movement by writing a piece of joke legislation that Republicans could point to as proof that Democrats aren't serious about climate change.