> I don't think this is really true.
Well... I don't know what to tell you but it is. In the 2016 election both Biden and Warren (two candidates that proposed a "green manufacturing" plan for climate change) both admitted that in the short term their plans would lead to a net increase in emissions. And in fact, in 2022 we saw the EU emissions decrease by 2.5%, China's decrease by 0.2%, but the US increase by 0.8% in large part due to their approach to climate change solutions.
https://www.iea.org/reports/co2-emissions-in-2022
> then the emissions required to build renewable infrastructure will be much smaller than the total emissions for all other causes
Let's look at electric vehicles as a more concrete example. A lot of people don't realize that around 10% of lifetime emissions of a vehicle are in its initial manufacturing... for an ICE vehicle. The production of an EV is much more expensive due to their batteries. And in fact over 30% of its lifetime emissions could be in the manufacturing of the battery alone. This is why, in the US, it takes around 28,069-68,160 miles before an EV is actually less polluting than an ICE vehicle.
https://news.harvard.edu/gazette/story/2023/08/when-buying-a...
That's a technology-specific example, but similar dynamics play out in many other ways. One simple one is just... infrastructure. The simple fact that we already have gas stations. We need to invest massive amounts of resources in order to build all these new electric vehicle charging stations
Yes we will (hopefully) soon see something like "economies of scale for emissions" come into play but it's hard to deny that there's a massive upfront cost to simply "building new stuff"