1. Why did they choose the two axis powers to draw their comparison?
2. What would be the cost, in additional carbon emissions, to procure, distribute, and deploy all that basalt?
Post WWII Germany and Japan are not the axis powers, so this question seems quite irrelevant. More likely Germany and Japan are two industrialized nations the sum of whose carbon emissions roughly equals the amount of carbon that could be offset by this process.
> 2. What would be the cost, in additional carbon emissions, to procure, distribute, and deploy all that basalt?
For the procurement, they claim near zero:
"Basalt is the best rock for capturing CO2, and many mines already produce dust as a byproduct, so stockpiles already exist. "
"Basalt is one of the most common rocks on Earth, and waste dust from mining could be used for ERW, as could waste from cement and steel manufacturing. This would remove the need to grind the rocks into fine particles, which requires energy. But how big these waste stockpiles are is unknown."
"“We are calling on nations to make inventories,” said Beerling. He said mines in Northumberland, UK, that produce basalt aggregate for construction produced 20-30% waste dust. But he said some mining specifically to produce basalt rock dust would probably still be needed, using existing mine capacity rather than new mines."
Even if I'm misreading it and parent is instead saying there's no correlation, there's still no need to be mean.