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We report on the lattice evolution of BiFeO3 as function of temperature usingfar infrared emissivity, reflectivity, and X-ray absorption local structure. Apower law fit to the lowest frequency soft phonon in the magnetic ordered phaseyields an exponent {\beta}=0.25 as for a tricritical point. At about 200 Kbelow TN~640 K it ceases softening as consequence of BiFeO3 metastability. Weidentified this temperature as corresponding to a crossover transition to anorder-disorder regime. Above ~700 K strong band overlapping, merging, andsmearing of modes are consequence of thermal fluctuations and chemicaldisorder. Vibrational modes show band splits in the ferroelectric phase asemerging from triple degenerated species as from a paraelectric cubic phaseabove TC~1090 K. Temperature dependent X-ray absorption near edge structure(XANES) at the Fe K-edge shows that lower temperature Fe3+ turns into Fe2+.While this matches the FeO w\"ustite XANES profile, the Bi LIII-edge downshiftsuggests a high temperature very complex bond configuration at the distorted Aperovskite site. Overall, our local structural measurements reveal hightemperature defect-induced irreversible lattice changes, below, and above theferroelectric transition, in an environment lacking of long-range coherence. Wedid not find an insulator to metal transition prior to melting.

High Temperature Emissivity, Reflectivity, and X-ray absorption of BiFeO3