Soumaya Keynes of the Economist has a great six part Special Report on World Trade. I really enjoyed it and highly recommend it! (Unfortunately, Soumaya is apparently leaving the trade beat, but this was a nice way to go out).
There were two small bits in the environment part that I have quibbles with, though, and I'll mention them here.
First, she says:
"In theory, the wto should be an ideal forum in which to consider environmental issues. Global problems of the commons require global solutions."
I completely agree with the second sentence, but I completely disagree with the first. In my view, there is no reason to think the WTO would be an "ideal" forum for environmental issues, or even a good forum. Certainly there is an overlap between trade and the environment, and WTO Members will have to come up with ways to address this. For example, an agreement to lower tariffs on environmentally-friendly goods could be useful; and we need clarity on how domestic environmental measures will be judged in WTO dispute settlement. But for the fundamental aspects of environmental issues (e.g. reducing carbon emissions), I don't see why the WTO would be the right place.
One reason I say this is that I don't think it's a good idea to deal with multiple global problems in one institution. That creates fears about some sort of "global government," and gets more than a few people riled up. People are riled up enough as it is -- let's not give them another reason!
Now, if the WTO were particularly effective at handling international rules on the environment, maybe it would be worth that risk. But the WTO is not particularly good at international rules on anything these days, so I don't see why it would be particularly effective here.
Overall, I don't see any advantages in doing this sort of global coordination at the WTO. It can be done anywhere, either in a permanent institution or through an ad hoc mechanism. Governments have certainly had trouble doing it, but the reason they are having trouble is unrelated to institutions or mechanisms. Rather, in my view, it's that most of them have simply been reluctant to take action in certain areas, such as climate change. If they wanted to take global action on climate change, they could. But they are all torn about it for one reason or another, so they haven't.
Second, she says:
"... the wto’s lawyers tend not to approve of discrimination based on how products are made, which is crucial if carbon-intensive products are to be treated differently from cleaner ones."
It is true that there is an approach to GATT/WTO non-discrimination obligations that goes something like this: If you have two products that are "like" in terms of their physical characteristics, but are treated differently pursuant to a regulation on the basis of how they were made, that will inherently treat at least one foreign product less favorably than one like domestic product, and that in and of itself leads to a finding of violation of GATT Article III or Article I with no further analysis needed. (There may be some variations on this view -- that was just a quick off the top of my head explanation).
However, I would say that while this approach used to be the dominant one, it is now an increasingly minority one, and it would probably not be applied by a WTO panel (or the Appellate Body or the MPIA) today. In my view, the existence of discrimination based on how different products are made is not directly relevant to the WTO's non-discrimination standards (in either the obligations or the exceptions), which instead should focus on issues such as the "design and structure" of the measure and should be centered around the concept of nationality-based discrimination rather than discrimination against particular products. A regulation that treats products differently depending on how they were made could certainly be challenged under these provisions, just as any regulation could. But you would still have to go through the full analysis under provisions such as GATT Articles III and I and the Article XX exceptions, rather than just assuming that a measure which treats carbon-intensive products differently from low-carbon ones leads to a violation. There's no doubt in my mind that a carbon regulation could be designed in a way that either does not violate or is upheld under the exceptions, although in practice governments tend to slip in some nationality-based discrimination, which is what often leads to problems.