Abstract: A thermally reversible water in oil in water (W/O/W) emulsion including a thermally reversible viscosifying polymer in the continuous aqueous phase of the emulsion. The thermally reversible viscosifying polymer of the W/O/W emulsion includes a block copolymer having at least a first polyoxyalkylene block having a hydrophobic region and a hydrophilic region effective to form micelles in solution in response to a change in temperature, and at least a second block comprising a poly(vinylcarboxylic acid).