Oil extended gains after the close as a decision by the U.S. and other major economies to release emergency stockpiles failed to ease concerns of a major shortfall in supplies as sanctions mount on Russia.

West Texas Intermediate crude closed above $80 a barrel for the first time since late 2014 as a growing power crisis from Europe to Asia boosts demand for oil ahead of winter.

Oil resumed losses after a brief bounce higher amid the aftershocks of a major index tracked by billions of dollars in funds exiting near-term contracts for fear prices may turn negative again.

Oil climbed Oct. 13 as dwindling U.S. crude stockpiles and near-record Chinese imports signaled the worldwide glut is eroding.

Oil closed at its highest level in five weeks, bolstered by a weakening dollar and speculation that OPEC talks next month could result in a crude output freeze.

Oil fell below $40 a barrel for first time since April, falling into a bear market on concern that the global supply glut will expand.

Oil tumbled to its lowest level in more than 12 years as crude stockpiles at the delivery point for New York futures expanded to a record.

West Texas Intermediate crude rebounded after sliding to the lowest level since July 2009 on speculation that prices have further to drop before OPEC’s decision to maintain output slows U.S. shale supply.