•A tree-planting project in Panama that promises profits for logging as well as calling itself a certified offset program when it is not. Few trees have even been planted.
•Scams in Australia that have prompted the alarmed government to launch a crackdown.
•A California promoter who launched a ship to spread iron dust in the South Pacific to grow carbon-sucking algae, a plan that the Environmental Protection Agency said would amount to illegal dumping at sea.
•An Israeli charity that is selling offsets that are supposed to create brand-new projects, for tree plantings it has been doing for 60 years.
Such examples are causing some supporters of carbon offsets to back off what they once saw as a promising tool to help the environment. And the troublesome record concerns those who want a national carbon cap-and-trade program in the US that would use offsets.