How, exactly, does Jim Hansen qualify as “the world’s leading climate scientist"?

Greenpeace Loves Some Jim Hansen « Carbonated Climate

Some of you may have read about the Greenpeace coal power plant fiasco in Kingsnorth. Some of you may not know how big of a crush Greenpeace has on Jim Hansen. When looking through their trial updates on the Greenpeace site, I noticed something. They didn’t mention Hansen’s name without referring to him as “the world’s leading climate scientist.”