The main source is battery production and related to the mining and refinement of their raw materials (source, source). The exact emissions are hard to quantify. That being said, the lifetime emissions of battery EVs are still significantly lower, so it’s still a net benefit. For a bigger picture, you can check the references here and here.
What’s the upfront emission of EV production that makes it that much of a detriment compared to ICE production?
The main source is battery production and related to the mining and refinement of their raw materials (source, source). The exact emissions are hard to quantify. That being said, the lifetime emissions of battery EVs are still significantly lower, so it’s still a net benefit. For a bigger picture, you can check the references here and here.