sentences:  Other researchers have suggested that a CLAW-like mechanism may operate in the Earth's sulfur cycle without the requirement of an active biological component.A 2014 review article criticised the model for being an oversimplification and that the effect might be much weaker than proposed.In his 2006 book "The Revenge of Gaia", Lovelock proposed that instead of providing negative feedback in the climate system, the components of the CLAW hypothesis may act to create a positive feedback loop.