And packaged foods company Conagra CAG.N warned raw material and packaging costs were hurting profit, a headwind that would not ease until late-2022. By Sujata Rao and Simon Jessop LONDON, Aug 11 (Reuters) - From container ships to cardboard, tighter environmental regulations are stoking shortages and price spikes as 'greenflation' takes a grip, adding a new twist to corporate valuations. For all the inflation-is-transitory messages from central banks, double or triple-digit cost increases have become common on company balance sheets, although the green variety has yet to show up in bond markets, the usual early warning system.