SAN DIEGO — San Diego leaders have declared a war on natural gas to dramatically shrink the city’s carbon footprint and reach net-zero emission by 2035. The City Council voted unanimously this week to approve a dramatically overhauled climate action plan that calls for banning the fossil fuel in new construction while also electrifying nearly all existing buildings over the next 12 years. Dozens of cities across California have restricted installation of gas stoves and heaters in new construction, including Encinitas. However, retrofitting entire neighborhoods would be a massive undertaking fo…