The cost to stop global warming would be rather more than 2.4 trillion. We’re rather dependent on fossil fuels. If global warming is only 2.4 trillion dollars it would be much more economical to suffer it than undergo the prescriptions of many environmentalists.
On the other hand, a carbon tax could at least raise some tax revenues while cutting greenhouse emissions in the most economical fashion. There would still be a major gross cost, but if it balanced the budget and/or replaced the income tax, the cost of reengineering the economy would be at least partly offset by the benefit of reduced spurious financial games.