Biodiversity and trade

So, this Nature paper has been a weekend hit. It links threatened species to trade routes and shows that trade is a cause of loss of biodiversity. Or so it argues.

I am not sure the paper supports that claim, though. Suppose monkey production threatens a species of coffee -- hmm, too early in the morning. Try again. Suppose coffee production threatens a species of monkey, and suppose that 90% of coffee is exported. The paper then argues that 90% of the expected biodiversity loss is also being exported.

We seem to be missing a counterfactual. What would happen if the trade weren't there (e.g. if it were banned)? Presumably economic activity would not stop but would be diverted to alternatives. Some of those would be more ecological, some would not. Subsistence agriculture, plus overpopulation, can be pretty devastating to habitats, right?

It is surely true that rich countries have exported environmental destruction to poor countries which have lower protections for public goods. (Although those countries may also put a higher priority on economic growth.) And biodiversity certification a la the Rainforest Alliance logo might be a solution. It's just that I'm a bit unclear what the paper is actually estimating.