What is the cost to turn back global warming by mid-century and keep the mean temperature rise to 1.5 Celsius? $131 trillion in U.S. dollars states IRENA as described in The Wall Street Journal. Meanwhile, the latest IPCC Working Group III report on mitigation strategies lays out the parameters and pathways needed to stay as close to 1.5 as possible although it means actions need to be taken in the next three years.