That's an excellent question.
In that hypothetical situation, the impact would depend on the relative GHG intensity of Canadian and U.S. or Canadian and EU production. If Canada, for example, was a lower GHG-intensity producer of wheat than U.S. producers, we would actually benefit from a border carbon adjustment imposed by the U.S., which would presumably put a price on carbon on U.S. production and impose one on Canadian production.
Now, the devil is all in the detail. It's unlikely that a U.S. proposal would put a price on U.S. production. If we're talking about a hypothetical charge on all imports entering the U.S., including agricultural goods, obviously we would suffer from that.
If we're talking about a CBAM-like mechanism, which is a more fair mechanism and which imposes a domestic price, and let's say they impose the price on their agriculture and mirror that price at the border—that's what a real border carbon adjustment is supposed to do—then again, it would depend on the relative GHG intensity of Canadian and EU production.
I'm not an expert in that area, but I know that EU agriculture is not particularly low-cost agriculture. I know also that the CBAM credits for carbon price paid in the country of export. Canadian agriculture.... In all of the other sectors I've examined that are covered by CBAM, Canada does well. Agriculture may be the same.
You have to do a quantitative analysis to answer authoritatively, though.