The United Nation’s 2015 Paris Agreement on climate change aims to limit the average global temperature increase to “well below 2° Celsius.” Achieving this means reducing carbon emissions to net zero, that is, balancing the man-made greenhouse gases being added to the atmosphere with the amount being removed in the second half of the 21st century.

Net-zero efforts are gathering momentum to meet this challenge. In June 2019, the U.K. set into law a target of being net zero by 2050 — the first major economy to do so. Several other European countries, along with Japan, South Korea and China, have since set legally binding, mid-century, net-zero targets. The European Commission plans to mobilize up to $1 trillion to help make Europe climate-neutral by 2050. After a four-year hiatus, the United States is also ready to work toward making its economy carbon-neutral by 2050. The two charts on page 29, “CO2 emissions from energy” and “Global energy demand,” illustrate