Data from the Sloan Digital Sky Survey (∼300,000 galaxies) indicate that recent star formation (within the last 1 billion years) is bimodal: half of the stars form from gas with high amounts of metals (solar metallicity) and the other half form with small contribution of elements heavier than helium (∼10%–30% solar). Theoretical studies of mass loss from the brightest stars derive significantly higher stellar-origin black hole (BH) masses (∼30–80 M☉) than previously estimated for sub-solar compositions. We combine these findings to estimate the probability of detecting gravitational waves (GWs) arising from the inspiral of double compact objects. Our results show that a low-metallicity environment significantly boosts the formation of double compact object binaries with at least one BH. In particular, we find the GW detection rate is increased by a factor of 20 if the metallicity is decreased from solar (as in all previous estimates) to a 50–50 mixture of solar and 10% solar metallicity. The current sensitivity of the two largest instruments to neutron star–neutron star (NS–NS) binary inspirals (VIRGO: ∼9 Mpc; LIGO: ∼18) is not high enough to ensure a first detection. However, our results indicate that if a future instrument increased the sensitivity to ∼50–100 Mpc, a detection of GWs would be expected within the first year of observation. It was previously thought that NS–NS inspirals were the most likely source for GW detection. Our results indicate that BH–BH binaries are ∼25 times more likely sources than NS–NS systems and that we are on the cusp of GW detection.