Climate Week is ending. What next?

Climate Week NYC is wrapping up. Marchers are filing out of Manhattan. Foreign dignitaries are headed home. 

After a week of climate-themed events and a global UN summit in New York, the international community will be without a comprehensive strategy to fight climate change.

Of course, that was never the point. The record-breaking march on Sunday, the lectures and panels throughout the week, and even the session at the UN were planned to function more as a pep rally – a way to build momentum in advance of negotiations in Lima, Peru later this year and in Paris next year. That's when the international community makes what many view as a last-ditch effort to enact a plan to slow and eventually reverse the upward growth of global carbon emissions. 

It will require herculean efforts – diplomatically,  economically, and technologically – to decarbonize the world's energy supply and lower emissions in other industries. Not everyone believes such an agreement on climate change is possible or even necessary. Past negotiations and their resulting agreements have at best underwhelmed. The global economy is still wobbly, and there are plenty of other issues – terrorism in the Middle East, ebola in West Africa, crisis in Eastern Europe – jockeying for resources and attention.

But if civilization continues to emit heat-trapping gases into Earth's atmosphere at its current rate, most scientists agree the consequences for populations around the globe will be disastrous. 

Where, then, do negotiators go from here? 

"Even though we are in a very complex process in the negotiation, I think what we have received from the [New York] summit has left for us a hope that we can deal with the problems and reach the objective," Manuel Pulgar-Vidal, Peru's minister of the environment, says in a telephone interview. "Our challenge is to maintain this message through Lima."

As president of the Lima summit in December – called the 20th session of the Conference of the Parties (COP20) – Minister Pulgar-Vidal has the unenviable task of overseeing negotiations among a diverse range of global interests. If they're successful, they'll walk away from the table with a rough-draft agreement that will serve as the basis for the final vote in Paris next year.

It will not be easy. There is a lingering divide between developed nations (namely the US, and Western Europe) and countries that are quickly industrializing, growing middle classes, and demanding a quality of life long enjoyed in much of the West. Foremost among them is China, but other countries in Asia, Latin America, and Africa are also experiencing quick growth spurts – buying and driving more cars, installing air-conditioners, and fueling it all with a lot of cheap, reliable, and plentiful fossil fuels.

The majority of future growth in carbon emissions is expected to come from these developing nations, so rich nations often emphasize the role China, India, and others should play. But it is the US, Europe, and others who saturated the atmosphere with carbon dioxide to begin with. They powered their own 18th- and 19th-century industrializations with carbon-heavy coal, largely unaware that the seemingly harmless gas it emits when burned would one day pose such a threat. It's why developing nations sometimes point to the West as the culprit. 

The hope is to transcend this divide. There is general agreement among negotiators that, as President Obama put it in his speech to the UN Tuesday, nobody "can stand on the sidelines on this issue." But the devil, of course, is in the details: exactly how to divvy up a vast, borderless challenge across very diverse and tangible borders.

One opportunity for forward movement, watchers say, is the UN's Green Climate Fund. Established in 2010, the fund is designed to spearhead clean-energy development in developing countries using private and public finance from rich nations.

"The Global Climate Fund is obviously very important," Pulgar-Vidal says. "Capitalization and mobilization of resources should create movement and send a strong political symbol."

But the fund has struggled to get off the ground, and some are concerned it will miss its initial fundraising target of $10 billion to $15 billion, which would make developing nations less likely to commit to a broader plan in Paris. So far, Germany and France have pledged a billion each, and others have made smaller pledges. Pulgar-Vidal says he's confident the fund will be between $10 billion and $15 billion by the end of November, as countries step up pledges in advance of the Lima talks.

Not all of it need come from government. Robert Stavins, who directs the Harvard Project on Climate Agreements at Harvard University, says one of the most noteworthy displays at this week's New York summit was the role private companies played. Apple, Ikea, and Kellogg, were among dozens of companies making clean energy and climate pledges of their own – or at least speaking out on the issue during Climate Week. And this time around, leaders inside the UN were actively receptive and supportive of the message.

"The business community always has been significant around the sidelines, but [the United Nations] has never embraced it as part of the solution verbally and publicly to the degree to which it did in New York," Mr. Stavins, who also directs Harvard's environmental economics program, says in a telephone interview. 

Some of that corporate support may be more public-relations strategy than substantive action, but many observers see private-public partnership as a much-needed, missing piece of the climate puzzle. That has made some more optimistic going forward – chief among them, UN Secretary General Ban Ki-moon:  

"As we look forward to Lima, later this year, and Paris in December 2015, let us look back on today as the day when we decided – as a human family – to put our house in order to make it sustainable, safe and prosperous for future generations," Mr. Ban said in his summary Tuesday. "Today’s Summit has shown that we can rise to the climate challenge."