Quantum evolution of near-extremal Reissner-Nordstrom black holes

We study the near-horizon AdS(2) x S-2 geometry of evaporating near-extrema l Reissner-Nordstrom black holes interacting with null matter. The non-loca l (boundary) terms t(+/-), coming from the effective theory corrected with the quantum Polyakov-Liouville action, are treated as dynamical variables. We describe analytically the evaporation process which turns out to be comp atible with the third law of thermodynamics. i.e., an infinite amount of ti me is required for the black hole to decay to extremality. Finally we comme nt briefly on the implications of our results for the information loss prob lem. (C) 2001 Elsevier Science B.V. All rights reserved.