Mr Ban's intervention came as efforts to agree a symbolic extension of the UN Kyoto Protocol, a treaty that obliges developed nations to cut greenhouse gas emissions, looked to be faltering.
In a speech to almost 200 nations meeting in Doha, Mr Ban said a thaw in Arctic sea ice to record lows this year, superstorms and rising sea levels were all signs of a crisis.
"The abnormal is the new normal," he told delegates. He said signs of change were apparent everywhere and "from the US to India, from Ukraine to Brazil, drought [has] decimated essential global crops".
"No-one is immune to climate change – rich or poor. It is an existential challenge for the whole human race – our way of life, our plans for the future," he said.
Urging nations to cast off their apathy and embrace ambition, he had earlier said Superstorm Sandy had "given us an awakening call".
The failure to agree a Kyoto extension is blocking efforts to lay the foundations of a new global UN deal that is meant to be agreed in 2015 and to enter into force from 2020. In 2009, a summit in Copenhagen failed to agreed a deal to succeed Kyoto.