In the long term - 200+ yrs. For the short term it is going to worse no matter what we implement today. Something that is going to have to sink in after everyone accepts that we need to do something about CC now. We are going to have big adaptation implications.

And this is only with an angry planet. Imagine if the sun got angry as well. Millenia of warming to make life in Earth possible, and this is how we pay back. If I was the sun, I would be furious. Not to mention the galaxy.

I say this not to be partisan (although I am) but rather to highlight the problem, so that we might see the solution more clearly.

And the solution is get the current crop of Republican deniers out of Congress.

To me, that’s the $64 trillion question: How close are we to that global tipping point? I don’t think anyone knows (even if we all have guesses), which is why I keep saying not only are we playing Russian roulette, but we don’t even know how many bullets are in the gun.

anyway this is my third choice for the tantrum/coincidence duality: a higher severity of a periodic event. maybe there will be a respite, the droughts and storms will relax, or maybe we’ll find out that el niño 2.0 sux worse.

[How close are we to that global tipping point? I don’t think anyone knows (even if we all have guesses), which is why I keep saying not only are we playing Russian roulette, but we don’t even know how many bullets are in the gun.]

At atmosphere’s CO2 concentration of 388 ppm plus the CO2 eq. gases (about 12% of CO2), climate forcing is about 434 ppm CO2 eq.

We are playing Russian roulette and we do know how many bullets are in the gun; bullets in all chambers.

John McCormick

Accelerated feedback is here.

How do you define “tipping point”?

If you mean when does the feedback cause runaway warming, then we are very far from that point. The earth survived 1500±500 ppm CO2 approximately 50 million years ago without runaway warming (though the sun was slightly weaker then). It did of course get very very warm as a result, but without turning the Earth into Venus.

If you define “tipping point” as simply leading to major damage to humanity and Earth’s ecosystems, then I opine that there may be multiple tipping points. The permafrost is one that is either imminent or we have already crossed (time will tell). Once the permafrost kicks in, it will accelerate warming until the carbon stored there is fully released. Then things slow down again, until the next tipping point is reached (unless it overlaps with the permafrost). When that next carbon store is used up, things slow down again, and so on. Similarly, there is a boost to warming when the temperature reaches a point at which polar ice melts. When that ice is gone, the rate falls back. The Earth’s sensitivity to CO2 is nonlinear.

Hansen’s analysis suggests that there is a tipping point at 425±25 ppm based on the observation that as the Earth reduced from 1500±500ppm at 50 million years ago (Mya) down to 425±25 ppm at 35 Mya, the Antarctic ice sheet started to form. Returning CO2 back above the 425±25 ppm point should begin to reverse that process (though it might take a while). Given that the permafrost has 500-1000 Gt of carbon to release, which is sufficient to raise atmospheric CO2 well above 450 ppm, it looks like these two feedback mechanisms overlap. That is unfortunate for us.

Hansen suggests that we eventually need to return CO2 to 350 ppm to keep things sane. We may temporarily exceed that (as we already have), but the longer we remain above 350 ppm, the worse the danger to us.

Bill McKibben likens the 350 ppm limit to a medical threshold. It isn’t instantly fatal to have a high test result, but if you don’t do something to return to the safe range, you’re likely to suffer severe consequences before too long.

Thanks Joe for making me aware of wildfire connection to climate change.