  Using cosmological hydrodynamical simulations, we investigate the prospects
of the thermal Sunyaev-Zel'dovich (tSZ) effect to detect the missing baryons in
the local universe. We find that at least 80% of the tSZ luminosity is
generated in collapsed structures, and that $\sim$ 70% of the remaining diffuse
tSZ luminosity (i.e., $\sim 15$% of the total) comes from overdense regions
with $\delta_{gas}>$10, such as filaments and superclusters. The gas present in
slightly overdense and underdense regions with $\delta_{gas} < 10$, despite
making up 50% of the total baryon budget, leaves very little tSZ signature: it
gives rise to only $\sim$ 5% of the total tSZ luminosity. Thus, future Cosmic
Microwave Background (CMB) observations will be sensitive to, at best, one half
of the missing baryons, improving the current observational status, but still
leaving one half unobserved. Since most of the tSZ is generated in haloes, we
find a tight correlation between gas pressure and galaxy number density. This
allows us to predict the CMB Comptonization from existing galaxy surveys and to
forecast the tSZ effect from the local structures probed by the Two Micron All
Sky Survey (2MASS) galaxy catalog.
