US President Barack Obama and his Chinese counterpart Hu Jintao have agreed to cooperate on a number of global problems signalling a possible new era in Sino-American relations.Climate change is a key issue others include trade and the nuclear ambitions of Iran and North Korea. But old sticking points remain with Obama calling on the Chinese to re-enter talks with the Dalai Lama over Tibet and human rights. The president himself suffered at the hands of the censor after his question-and-answer session in Shanghai received the air-brush treatment. Obama spent some time visiting the Forbidden City and appeared to be enjoying his first trip to China. “Obviously on my first visit to China I wanted to go to Shanghai and Beijing but, I hope the next time I come I get to go to some other parts of the country,” he said. Major issues such as the value of the Chinese yuen and America’s new tariffs on Chinese-made tyres, steel pipes and other products are still to be resolved, but further rounds of talks on a raft of topics are promised.