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The intrinsic escape fraction of ionizing Lyman continuum photons ($f_{esc}$)is crucial to understand whether galaxies are capable of reionizing the neutralhydrogen in the early universe at z>6. Unfortunately, it is not possible toaccess $f_{esc}$ at z>4 with direct observations and the handful ofmeasurements from low redshift galaxies consistently find $f_{esc}$ < 10%,while at least $f_{esc}$ ~ 10% is necessary for galaxies dominate reionization.Here, we present the first empirical prediction of $f_{esc}$ at z>6 bycombining the (sparsely populated) relation between [OIII]/[OII] and $f_{esc}$with the redshift evolution of [OIII]/[OII] as predicted from local high-zanalogs selected by their H$\alpha$ equivalent-width. We find $f_{esc}$ =$5.7_{-3.3}^{+8.3}$% at z=6 and $f_{esc}$ = $10.4_{-6.3}^{+15.5}$% at z=9 forgalaxies with log(M/M$_{sun}$) ~ 9.0 (errors given as 1$\sigma$). However,there is a negative correlation with stellar mass and we find up to 50% larger$f_{esc}$ per 0.5 dex decrease in stellar mass. The population averaged escapefraction increases according to $f_{esc}$ = $f_{esc,0} ((1+z)/3)^a$, with$f_{esc,0} = 2.3 \pm 0.05$% and $a=1.17 \pm 0.02$ at z > 2 for log(M/M$_{sun}$)~ 9.0. With our empirical prediction of $f_{esc}$ (thus fixing an importantpreviously unknown variable) and further reasonable assumption on clumpingfactor and the production efficiency of Lyman continuum photons, we concludethat the average population of galaxies is just capable to reionize theuniverse by z ~ 6.

Revisiting the Lyman Continuum Escape Crisis: Predictions for z > 6 from Local Galaxies