"Climate change is the defining issue of our times," Ban has said over and over again, urging that "now is the time for action."
And this week the heads of UN member countries appear to have taken up the challenge. One after the other, leaders pledged billions for a global climate fund to help developing nations, set specific targets to cut greenhouse gas emissions and promised greater use of clean energy.
But promises in the hot media glare — and mass demonstrations — of New York are one thing. There’s still the matter of whether the steps needed to mitigate global warming will actually be taken after the summit wraps up and all the brouhaha fades.
Scott Vaughan, the president of the Canadian-based International Institute for Sustainable Development, is confident they will.
"Everybody is absolutely focused on what needs to be done practically, concretely to get an agreement in 2015," he said in an interview with CBC News, referring to the next key climate conference to be held in Paris next year.
Of course the cautionary tale here is that the last international climate negotiations in Copenhagen in 2009 failed to produce a binding agreement among countries to enact effective policy to reduce greenhouse gas emissions.
Vaughan, who's in New York meeting with some of summit participants and tracking pledges, said the New York summit is a "game-changer if anything is," and cites the convergence of civil society, corporations and many key governments in tackling climate change.
In recent decades, climate change policy has aimed to prevent the Earth from heating up by a global average of 2 C above pre-industrial times.
However, the failure of world governments to commit to any lasting action at past meetings likely means a 2 C rise is a foregone conclusion, some scientists say, pointing to the fact that the average temperature has already risen nearly 1 C since the 19th century.
Now, negotiators and researchers are scrambling to keep us from heading towards an increase of between 3 C and 4 C by the end of this century.
Vaughan said there are two goals to work towards: reducing greenhouse gas emissions and providing support for the most vulnerable countries to adapt to climate change.
For the latter, French President Francois Hollande, the host of next year's climate conference, pledged $1 billion. Other EU countries such as Denmark and Switzerland have made similar commitments.
As for reducing emissions, that involves a shift away from fossil fuels in favour of renewable energy, something Greenpeace Canada said is already happening.
"For the U.S. and China, their biggest problem, in terms of greenhouse gas emissions, is coal," said climate and energy researcher Keith Stewart.
"Both countries are actually taking measures to reduce coal and that's the kind of thing that builds trust," he said. The U.S. and China are the world's two biggest producers of carbon pollution.
Corporations jumping on the bandwagon
This past summer, U.S. President Barack Obama announced a proposal to cut carbon pollution by 30 per cent from 2005 levels by 2030. The main way to carry out that rule would be by limiting emissions from coal-fired power plants.
China, the world's biggest GHG emitter, last year invested $54 billion in renewable energy and is the world's biggest provider of wind, solar and other clean energy technologies, according to data by the Pew Charitable Trusts.
Part of that, said Ian Bruce of the David Suzuki Foundation, is because of China's toxic air pollution. But the other aspect is that high carbon fossil fuels are risky investments.
"The cost of renewable energy has decreased almost 100 per cent over last five years," said Bruce, the foundation's science and policy manager, "while the cost of fossil fuels has been very volatile and on the rise."
That cost equation helps explain why corporations are jumping on the bandwagon and attended Tuesday's summit.
"Certainly, having 200 CEOs in the room at the UN right now underscores that they are as concerned about their sustainability as civil society is," said the IISD's Vaughan.
The World Bank also announced that more than 1,000 businesses — along with 73 countries and 22 states, provinces and cities — have expressed their support for carbon pricing. Not to mention the announcement of the Rockefeller Brothers Fund selling $50 billion US worth of fossil fuel assets in an effort to fight global warming.
"When the family that built the very first multinational oil company says it's time to get out of fossil fuels, this is an important moment," said Greenpeace Canada's Stewart.
"And when you have these things coming together, there is an opportunity for politicians to actually lead rather than tell us why they can't do anything."
Strategy needed, not pledges
Still, Scott Barrett, a natural resource economics professor at Columbia University's Earth Institute and a former lead author of the UN's Intergovernmental Panel on Climate Change, is not convinced anything concrete will come out of the Paris climate conference, despite the enthusiasm on display in New York.
"The real problem is at the global level," said Barrett. "We have not found the means to change the incentives to get the countries to actually adopt limits, essentially on emissions."
He said international treaties are not enforceable, even when they are legally binding. Using the example of the 1997 Kyoto Protocol, Barrett said the U.S. didn't participate and Canada ended up withdrawing.
"Unfortunately in the climate area, strategy is the last thing that anyone is ever thinking of as far as I can see, because they keep coming up with ideas like pledges which imply that you can, by some kind of central planning, ordain a collective outcome and the world doesn’t work that way," he said.
There is one bright spot, he noted, in the effort to fight climate change — the 1987 Montreal Protocol, an international treaty to protect the ozone layer by phasing out chemical substances that deplete it.
Those substances — chlorofluorocarbons (CFCs) — are also powerful greenhouse gases.
The power of the Montreal Protocol lies in the ability to ensure signatories follow the rules by prohibiting certain trades with other member parties.
Since its implementation, the Montreal Protocol has reduced CFCs by the equivalent of 135 billion tonnes of carbon dioxide, according to a 2007 book published by the UN Environmental Program.
Barrett said the protocol is a solution to a small problem, but it is a solution nonetheless.
"We've been doing this for 25 years and we’ve failed for 25 years," he said. "We need to come up with newer approaches, people don't want to repeat the past mistakes."