It is one of most popular plans among economists for addressing climate change. Many Democrats have embraced it. Even some Republicans have come around to the idea. But a carbon tax is increasingly out of favor among left-wing climate activists, who are animating the push for a Green New Deal. These progressives argue that simply charging a tax on those who emit carbon dioxide and other heat-trapping gases would be too little, too late given the amount of greenhouse gases humans have put into the atmosphere. “Carbon tax is often treated as a magic bullet,” said Nicole Ghio, the fossil fuels program manager at the environmental group Friends of the Earth. “It’s unrealistic to expect a carbon tax on its own to solve the climate crisis.” Other environmentalists have begun treating any pricing-carbon plan with outright hostility. […]