Guardian: China must be far more ambitious in tackling climate change if the international community wants to prevent calamitous levels of global warming, a senior US official told counterparts in Beijing today. David Sandalow, assistant secretary of state for energy, said the continuation of business as usual in China would result in a 2.7C rise in global temperatures by 2050 even if every other country slashed greenhouse gas emissions by 80%. “China can and will need to do much more if …