The growing urgency to address climate change and concerns about the financial performance of Exxon Mobil aligned this week to help activist investors place two directors on the company’s board. But it is not clear if the activists can deliver on their dual goals — reducing the emissions that are warming the planet and lifting the profits and stock price of Exxon. The potential tensions between those objectives could doom the investor effort to transform the company and the oil industry. Getting Exxon, a behemoth company with $265 billion in revenue in 2019 and oil and gas fields around the world, to switch to cleaner energy will be a yearslong and difficult process. It is unlikely to produce quick returns and could sap profits for a while as the company spends a small fortune to retool itself. And the biggest investment firms, which lent critical support to the activists and control a lot of Exxon’s stock, may be too timid to keep the pressure on company executives and board members