What counts as a real biosignature vs a false positive in exoplanet spectra?

[Emily31]

I was reading about the new results from the James Webb Space Telescope and it mentioned the detection of a potential biosignature on an exoplanet. I'm having a hard time understanding how they can distinguish a real atmospheric biosignature from a false positive caused by geological processes. It seems like such a huge claim to make from just a light spectrum.

[Brian36]

I skimmed it too and it feels like a giant claim from a flicker in a spectrum

[James.A]

What helps in practice is not a single line but a pattern they look for more than one molecule in the right proportions and for disequilibrium that does not sit with simple geology That can point toward a biosignature but it's not proof

[Jack.J]

They also test with models of the planet atmosphere and check how clouds and hazes might color the signal and compare to what JWST could actually resolve It feels tentative and iterative rather than definitive

[NoraG]

Are we sure the problem isn't that we are chasing a single signal when planets are messy and the data is loud I mean maybe the real limits are methodological not just the spectrum