At a time when crises like the conflict with the 'Islamic State' movement, Ukraine and the spread of Ebola are dominating the global news agenda, Ban effectively reminded the world that climate change poses an overriding threat.
Droughts could endanger food security, sea level rise and extreme weather could jeopardize huge populations, sparking waves of migration and possibly conflict.
Bringing the climate message home
This was not a negotiating summit but a giant demonstration that the leaders of the world have finally recognized the need for urgent action. CO2 emissions have reached record proportions and are still on the rise. If the world is to have even the remotest chance of limiting temperature rise to two degrees Celsius, there is no alternative to drastic emissions cuts - now.
At the New York summit, the world's top emitters - the United States and China - openly accepted responsibility to lead the world in tackling climate change. China pledged to take firm action and to make deep emissions cuts by 2020.
US President Barack Obama reiterated his commitment. In spite of massive opposition from the US Congress and the fossil fuels lobby, Obama is using the negative health impacts of emissions to regulate them by executive power.
The president of the world's second biggest polluter wants to make climate action his legacy. Even in what is arguably the climate skeptic of nations, the message is finally coming home.
Major emitters take on responsibility
China and the US are not acting out of altruistic motives. Both are already feeling the impacts of a warming world. The US is suffering from drought and extreme weather. China is additionally crippled by air pollution from climate killer coal. And there's nothing better than disaster on people's doorsteps to convince them that unpopular action is crucial to halt climate change.
Key deals on stopping deforestation and agriculture were set in motion in New York. Money for the Green Climate fund was pledged. France promised $1 billion dollars (750 million euros) to match Germany's pre-summit pledge. Admittedly, there is still far too little in all. Oil-rich Norway entered into an exemplary partnership with Liberia to end deforestation there by 2020.
Time is running out
The large presence of corporate leaders, regions and cities in New York and the demonstrators on the streets around the world point the way forward. Climate change requires action from all. With emissions still on the rise, the world cannot wait for a paper deal, however crucial that might be.
The key role Ban allocated to new UN climate ambassador Di Caprio shows that he has understood how to engage the public. In our media-dominated world, celebrities can help get a message across.
But this is not a Hollywood movie. There will be no super hero, no magical powers. The everyday business of climate protection has little to do with the sparkle of the movie world.
Governments have to keep up with their homework, creating conditions for a switch to a green economy. The fossil fuels industry has to accept its responsibility for the world's climate plight and play its role in tackling the problem.
The biggest top-level climate show since the debacle of Copenhagen in 2009 has breathed new life into the climate process. But the world needs more than a one-off show. The rest of the series is still to come. And time is running out.