The new deal is not legally binding and can’t, on its own, force any country to act. Yet many of the politicians, environmentalists and business leaders gathered in Dubai hoped it would send a message to investors and policymakers that the shift away from fossil fuels was unstoppable. Over the next two years, each nation is supposed to submit a detailed, formal plan for how it intends to curb greenhouse gas emissions through 2035. Wednesday’s agreement is meant to guide those plans.