The International Energy Agency cut its oil-demand growth forecast for this year by more than a fifth, predicting global consumption is easing dramatically, even as producers show few signs of cutting back output. Crude prices tumbled. The prospect of unchecked supply has hit global oil prices hard over the past two weeks amid signs of a deep split among members of the Organization of the Petroleum Exporting Countries. The grouping of some of the world’s biggest oil producers hasn’t been willing to rein in output to help bolster prices. Instead, members have been reducing prices in an effort to boost, or defend, their global market share. Slowing economic growth in Asia and a sputtering European economy have also weighed on prices over the past few months. Those worries intensified Tuesday after the Paris-based IEA, in its closely watched monthly oil-market report, cut its forecast for global demand growth by about 22%. It now forecasts demand will climb a meager 700,000 barrels a day this year, about 200,000 barrels a day lower than previously forecast. Global oil demand is just over 92 million barrels a day.