An apocalypse half a billion years away? In what context does the word "fears" make sense on that kind of scale? If we're still around then, and still dependen

An apocalypse half a billion years away? In what context does the word "fears" make sense on that kind of scale? If we're still around then, and still dependent on this planet, and haven't transformed it into an entirely different ecosystem (all these ifs seem incredibly unlikely), then as you say there are easy fixes that even we at our current technological level could pull off. So I'm not clear why Ward would "fear" this.