But not too late for 4. Urgent action needed to prevent worst-case climate change scenarios and limit repercussions of abrupt runaway climate change..... OR, that's what I used to think, 5+ years ago; NOW I think it is indeed too late; we're f'd. Tipping points have tipped. Positive feedback effects in play. Bring on the methane. Abrupt climate change on the horizon. Exponential changes will escalate. Homo sapiens may not survive the current on-going 6th mass extinction.