2) Agents in the current system have incentives to prioritize short term benefits over longer term benefits. And a lot of climate related things are short term cost/investment for "profitable" long term benefits ; the current system sucks big time in this configuration.
3) The people having the least negative impact from climate change are the countries emitting the most greenhouse gas. The countries the more negatively impacted by climate change are countries contributing the least to climate change. There is a big misalignment of interest there making a purely "free market" "economical" solution difficult.
4) There are a lot of case in the real world were there is a strong economical incentive to switch to something different and were the different agents just don't... Because people don't want to change, because there can be some particular interest in the system, because of political motive... Human is not a rational animal, and his rationality is not only dictated by money
5) We need to do more than just switching from fossil to "green electricity"