Gov. Gavin Newsom has been positioning himself as a global climate leader this year, evangelizing California environmentalism in China and at the United Nations. But at home, he is increasingly at loggerheads with leading environmentalists. Environmental groups and tribes say the governor’s plan to protect water supply from climate change will exacerbate existing ecological devastation and irreversibly damage the Sacramento-San Joaquin River Delta, the central hub of the state’s water system. While this relationship has been fraying for years, a new fault line opened this month when Newsom used newfound authority to fast track approval for the largest proposed piece of concrete water infrastructure to be built by the state in decades.