GRUNDY COUNTY, Tennessee — For much of human history, the way to make money from a tree was to chop it down. Now, with companies rushing to offset their carbon emissions, there is value in leaving them standing. The good news for trees is that the going rate for intact forests has become competitive with what mills pay for logs. …Preserving trees is rewarded with carbon-offset credits, a climate-change currency that companies can purchase and apply toward a tiny portion of their tab. But lately, big energy companies are looking to preserve vast tracts of forest beyond what they need for California, as part of a burgeoning, speculative market in so-called voluntary offsets. One of the most enthusiastic, BP PLC, has already bought more than 40 million California offset credits since 2016 at a cost of hundreds of millions of dollars. [We respect the copyrights of the source publication – full access may require a subscription]