The present invention provides methods and systems for continuous polymerization of ethylenically unsaturated monomers in a water-in-oil inverse emulsion under adiabatic conditions without the need for external cooling during the polymerization. The method comprises neutralizing a monomer composition comprising at least one acidic vinyl monomer with a base in an aqueous medium comprising water and water ice to form an aqueous monomer solution therefrom; homogenizing and degassing to form an inverse monomer emulsion; initiating polymerization; passing the inverse emulsion through a tube reactor without cooling, and flash evaporating a portion of the water from inverse emulsion to cool and concentrate the resulting polymer-containing inverse emulsion. During neutralization, the aqueous medium comprises an amount of water ice sufficient to maintain a temperature of 30°C or less, and the polymerization is initiated by adding a free-radical polymerization initiator to the emulsion prior to passing the emulsion through the tube reactor.