The international activist is believed to be about to expose the global architect's 'greenwash' - where he says all the 'right things about saving the planet' but doesn't act on them.
Gehry is currently working on the King Alfred Leisure Centre site in Hove, all the way from his California headquarters.
Other to have come under attack from Monbiot include Coldplay lead singer Chris Martin, Tory leader David Cameron, veteran entrepreneur Richard Branson and Tesco chief executive Terry Leahy.
The process of exposing 'greenwash', according to Monbiot, is to dig behind the rhetoric people deliver about climate change and reveal whether they follow up their words with action.
According to Monbiot's website, www.turnuptheheat.org, this process is not designed to reveal everyone as a 'fully-fledged climate criminal'.
Instead, it intends to scare well-known figures who 'make inflated claims about their environmental performance, urge other people to do as they don't or help corporations to greenwash their public image'.
Gehry's workload sees him jetting all over the world to meetings about many different schemes in different countries.