The process of shipping of beef from Buenos Aires to Brussels has a much smaller climate impact than the process of producing that beef in the first place. In particular, the methane burped up from cows has a gigantic impact on radiative forcing in the upper atmosphere. And again, the amount of beef being allowed to be shipped to Europe is quota'd to a quite amount relative to the domestic industry.

That's not to say that we shouldn't do anything about these emissions, but the solution is going to be to develop more climate friendly shipping techniques, not to eliminate global trade.