[tremon]

One simple place to start is placing large taxes on the most harfmul activities (e.g. generating co2). This should incentive increased investment in safer energy sources.

This was the basis for the Kyoto Protocol [1] in 1997, which sought to limit greenhouse gas emissions by making organizations pay for a license to emit greenhouse gases. It even put most of the burden on developed nations, as you suggest.

Now, you may argue that the costs for licenses were not steep enough, or that the resulting emissions trading market diluted the effectiveness of the regulation, or that the US' refusal to ratify it makes effectively a failed attempt -- but what you propose has been tried before.

[1] https://en.wikipedia.org/wiki/Kyoto_Protocol