Carbon Offsets Are Taking Off, but They Aren’t All Created Equal

Projects range from restoring mangrove swamps to drawing carbon dioxide from the air with machines, but some climate experts warn against relying on offsets

The business of carbon offsets is evolving fast, leaving companies to navigate a dizzying market for services that aim to cancel out greenhouse-gas emissions.

Carbon offsets remove or avoid adding greenhouse gases to the atmosphere—a process that needs to happen on a vast scale to avert disastrous climate change, according to the projections of some scientists.

Businesses...