By Leela de Kretser and Alexander Smith DAVOS, Switzerland (Reuters) – U.S. Secretary of State Antony Blinken told business and political leaders in Davos on Wednesday he could not think of a time in his career when there had been more global challenges, ranging from war in Gaza and Ukraine to tensions over Taiwan. Blinken said that almost none of the problems that U.S. President Joe Biden’s administration wanted to address could be tackled in isolation, echoing comments on Tuesday by Chinese Premier Li Qiang, who called for greater global cooperation. Describing the conflict in Gaza as “gutwr…