Maybe I can provide a little more context than a he said, she said on how these carbon marketplaces work. The ones that I am most familiar with are soil carbon credits, even though I and a brother have properties enrolled with NCX (more on that in a bit). I did my PhD research on soil carbon sequestration and used carbon modeling to better understand management practices that affect soil carbon changes over time. In my current job, my company partnered with a carbon exchange on enrolling farmers into a program that pays them based on changes in management practices that are affecting soil carbon changes. The company I am working with is Indigo Ag and they are the largest and most accurate from the exchanges I have looked at. Again, I can only speak to soil carbon. Indigo works by creating registries for companies to purchase the carbon credits that farmers are selling through Indigo. Companies and investment groups are purchasing these credits for a multitude of reasons, but the two main ones are for off-setting their own emissions because they think it is important and/or they are doing it for good PR. There is currently zero government support for these carbon credits, and this was true before and after Biden took over. There is an overwhelming demand for carbon credits that is fueled entirely by the private sector (at least here in the US). When the Biden administration said that they would not include carbon credits in the infrastructure bill or in the farm bill, there was no effect on the price of carbon credits, because there is currently much higher demand than supply. The true market value for a soil carbon credit is somewhere around $27/credit. This is expected to at least double or even triple based on current demands and the rate of increase in farmer enrollment (supply).
Now as far as accuracy is concerned, this is where I can speak with a little more authority. Within the soil carbon credit space, the quality of the registries determines consumer confidence in the system that is currently entirely motivated by a carrot and not the stick. In other words, companies that are purchasing carbon credits are demanding to see the models that are verifying that they carbon credits they are purchasing are in fact carbon off-sets. Indigo currently verifies through soil testing the amount of carbon sequestered in about 60% of the farms enrolled. It is just about impossible and cost prohibitive to measure soil carbon changes on every farm. I am not sure how intensive NCX is using direct measurements in the field to verify their models, but I can say that mine and my brothers and several others on this forum have had their properties sampled, so they are at least doing some due diligence. How much is done is probably a function of cost of the on-site analysis and the demand from NCX's customers. I honestly don't know the first thing about forestry carbon credits, but I can say that at least some soil carbon credit exchanges are very solid and at least rooted in the most up-to-date science when selling carbon credits.
