[djaahk]

The first thing to determine, as with any challenge, is goal definition and scope. What do we mean by "fixing the Earth", and for what stakeholders.

A few potential goal definitions which can be wildly contradictory: - maximise the probability for Earth to remain habitable until cosmic conditions (the Sun's decline) dictate otherwise, for humans, - ibid, but for for as many species as possible, - identify and implement the most optimal way to coexist as a species toaximised learning and knowledge advancement, - etc.

It feels like long-term, multi-national, consequential fundamental research could be undertaken on an interesting scale with such a budget. This in turn could highlight scenarii of different ways forward to inform and influence policy-making. It may be one of the best ways to spend it.