Nej de är inte inställda i samma universum, men de kan dela liknande landmärken.
Från Tor-webbplatsen:
It was a pleasant surprise to discover that Robinson actually starts his new novel 2312 in Terminator, the moving city on Mercury, taking the concept from Blue Mars (and, I later discovered, from another novel and short story) and using it as a building block for what may be his most ambitious novel to date: a future history of the solar system, set exactly 300 years into our future. However, one thing should be explained right from the start: despite the similarity of the city on Mercury, 2312 is actually set in a completely different timeline from the Mars trilogy, one in which Mars took a different path. So: a standalone novel, not a sequel. --Tor.com