World Bank chief economist Indermit Gill predicts a "lost decade" for the world's economy. The official World Bank’s report "Falling Long-Term Growth Prospects: Trends, Expectations, and Policies" reads that "the theoretical growth rate an economy can sustain over the medium term based on investment and productivity rates without risking excess inflation is expected to fall to a three-decade low between now and 2030." The paper notes that a span of nearly three decades of sustained economic growth has ended. "The global average potential GDP growth rate is expected to fall to a three-decade low of 2.2% a year between now and 2030, down from 2.6% in 2011-21," the report states. Ayhan Kose, director of the World Bank's forecasting group, said: "It will take a herculean collective policy effort to restore growth." At a global level, given the cross-border nature of many challenges confronting growth, the policy response requires stronger cooperation and reenergized push for the mobilization of private capital. Kose pinpoints that developing countries should repeat their best 10-year improvement in different sectors.