Well the president did suggest we take forest floors to prevent wildfires, so..

I suspect that you'd just get lots of mammoths sunk in the mud.

While the scale required is huge, mammoths are just one of the players here. I am not sure if you have heard of pleistocene park were they have started with horse, karibou, sheep, yak and a few others and already seen some effects. All those animals are seeking plants in some form or the other in the winter and by doing so move the snow cover that is insulating the permafrost, letting the cold seek deeper into it (or rather letting the warmth diffuse out). Mammoths are a key species as they as larger mammals are more prone to trampel down larger vegetation like trees to create the ecosystem all together.

> But the scale required to make a difference, and the cost to get to that scale boggles my mind. You can't just whip up one pack of mammoths and call it a success...

I assume the idea is that if you can create your big furry von Neumann machines correctly in the first place, you only need to whip up one pack of mammoths and it will indeed then be a success eventually.

It defies logic but case in point: the re-introduction of wolves actually changed rivers in Yellowstone: https://www.youtube.com/watch?v=ysa5OBhXz-Q .

Not claiming this proposal will have the same impact, or even a positive one.

Also hire only one IT guy.