UN chief Ban Ki-moon appealed for world powers to make a new effort to secure a legally binding climate deal next year amid new diplomatic wrangling over the failure of the Copenhagen summit. China hit back at Britain over claims that Beijing had "hijacked" the Copenhagen negotiations while Brazil and Cuba lashed out at the US President Barack Obama. With scientists warning of the growing threat of drought, floods, storms and rising sea levels, Ban acknowledged international disappointment over the summit accord on restraining rising temperatures.