Exxon Mobil Corp’s latest shift on climate includes a $1 million donation to a political action committee’s lobbying campaign to promote a U.S. tax on carbon-gas emissions, a central factor in global warming.  The contribution, made to the Americans for Carbon Dividends political action committee of the Climate Leadership Council (CLC), was disclosed by the group on Tuesday, less than a month after Exxon agreed to contribute $100 million to oil companies’ efforts to develop technologies to reduce greenhouse gas emissions. “Applying a uniform cost across the economy is consistent with our principles on how to manage the risk of climate change,” Exxon spokesman Scott Silvestri said in an email. […]