Whatever a genius like Hawking says is obviously significant.

The advantage of Hawking is that he is steeped in the scientific method, and then some. Is he saying that we are at a position of dynamic equilibrium, of instability made stable by lots of feedback loops which can just turn into feed-forward loops as soon as certain boundary conditions are breached ? Sounds like it.

In such an unstable system I suggest that tinkering with just one of the elements which pushed us to instability is unlikely to be the holy grail to re-stabilize the system, just simply because there are so many variables at play.

If we are to do “climate engineering”, which even a reduction of CO2 levels is in truth, we ought to be trying to jig a number of variables into place, particularly variables which we can fine tune as time goes on.

The most important variable is obviously incident solar radiation. Probably the reflection of incident solar radiation from the high atmosphere is another, which is likely correlated with surface albedo (white stuff, including ice, clouds etc…)

We have to start thinking about climate as a system, and take away climate control from those pursuing another agenda, related to a return to the “good old days”, to primitive magical thinking about the ills of civilization and how nasty humankind is to the Earth.

The Earth does not owe any particular civilization a living, things change, and we are changing them. We have allowed our population to increase, and in some places this is already, or will soon become, unsustainable (sea level changes, climate changes and other stuff.)

Humanity was around during the last ice age, and obviously survived that. Presumably this would not have been survivable for all, and one can imagine (or try to) what a rapid development of an ice age would do to today’s world. This should make us humble, and more determined to bite the bullet on climate engineering.