You’ll hear lots of pledges from companies and governments to cut the greenhouse gases they release to “net-zero.” …But how to get there? That’s where the concept of carbon offsets comes in, though their use is controversial. What’s a carbon offset? …What’s the appeal? For many industries, the cost of addressing their climate pollution can be daunting. Offset projects that plant trees or destroy landfill methane might reduce heat-trapping gases for a fraction of the cost. By allowing companies or governments to pay — and take credit — for cheaper emission reductions beyond their own field of activity, the cost of addressing climate change becomes less formidable. …How big is the market for carbon offsets? …What’s the problem with carbon offsets? …The market is flooded with blatantly non-additional projects — like conservation groups or local governments selling offsets for preserving trees that weren’t going to be chopped down anyway.