Yes, but the lifetime emissions are much lower than diesel buses. Although GHG emissions for buses are difficult to measure and compare we can look at cars to compare EVs and fossil fueled vehicles.
Current estimates say that producing an EV emits about 50% – 100% more GHG than a fossil car due to the battery. This impact is quickly off-set by reduced GHG emissions in use. e-Buses are expected to run for 1,000,000 km over their lifetime, off-setting about 1850 tonnes of Co2 emissions.
There is nothing intrinsic about the emissions of battery production. Lead by companies like Tesla and Volkswagen, efforts are underway to decarbonize the battery supply chain so that emissions are reduced or eliminated at each step. You can read about Volkswagen’s efforts here.
When the time comes to buy electric buses, one of the factors that should be rated equally with cost and capabilities is the carbon footprint of bus production.