Like it or not but we're already well into the "unimaginable disaster" phase for climate change.
The biggest group of climate change denialists are those scientists that insist we can cap things at 2°, which at this point is about the same as thinking that Santa is real.
I'm not a climate change denialist, but I am a climate change optimist. I think it would be possible to cap things off at two degrees, but we would have to start sucking CO2 out of the atmosphere and doing something with it (like big tanks or put it underground as dry ice, etc). Anyone that thinks we can stop this by producing less CO2 is deluded. We're well beyond the "unmitigated disaster for our current environment" ppm level.
If we can't fix this, at least life will evolve and move on after we and many other species go extinct due to human activity.
I have suspicions that most world leaders are aware of the work done on the various geo-engineering mitigation strategies and are willing to risk it.
Such a terrible prospect to consider but that hasn't stopped scientists and engineers planning for the worst. An ill-conceived quick fix scares me, yet seems to be more likely than global agreement to reduce emissions in the fractured world of international politics.
Actually, what is not appearing in those calculations, that the ability to react with technology might shrink due to the costs added by the migrations out of parts of the earth that become uninhabitable.
The problem with this is funding. If one country took it upon itself to save the planet they pay a huge price and everyone benefits, so there's no incentive to do it.
It's only when things get so bad there's no option but to do it, by which it's probably too late, when everyone might decide to fuck it and go solo instead of waiting for consensus.
True, but don't forget that large scale events also would occur without human intervention. It cant be denied that our actions are the cause for a lot of changes, but a volcano or an earthquake are just natural occurences. We live on a big ball of mud.
A significant element of the present era is that several distinct existential risks humans face are either self-imposed or self-inflicted.
Climate change, overpopulation, mass extinction, resource exhaustion, the threats of nuclear war and winter, self-imposed mass epidemic (particularly biowarfare), long-term chronic pollution (especially lead, mercury, and dioxins), ozone layer, mutagens, genetic drift.
Others aren't directly imposed but are self-inflicted: systemic global supply-chain collapse risk, global financial system collapse risk, creating potential breeding grounds and vectors for global pandemics, etc.
The risk of exogenous events -- supervolcanos, asteroid impacts, solar storms, nearby supernovae -- aren't affected by human activities. But in the case of endogenous events, we're directly affecting the probabilities.
The biggest group of climate change denialists are those scientists that insist we can cap things at 2°, which at this point is about the same as thinking that Santa is real.