New York-At the United Nations Climate Summit today, the world's two biggest emitters of greenhouse gases, China and the United States, both held off on making any specific additional pledges regarding their future emissions. In 2012, humanity emitted 36 billion tons of carbon dioxide into the atmosphere, of which 10 billion came from China and 5.2 billion from the United States. Convened by General-Secretary Ban Ki Moon, the Summit is supposed to "catalyze action" in advance of the big U.N. climate change conference at Paris in 2015. At the Paris conference, the nations of the world are supposed to make pledges to cut their emissions sufficient to keep future warming below the internationally agreed upon threshold of 2 degrees Celsius. It is not at all clear that today's Summit catalyzed much more than pious clichés.

In his remarks before the U.N. General Assembly, President Barack Obama opened by noting that while the world is confronting the current issues of terrorism, instability, inequality, and disease, "there's one issue that will define the contours of this century more dramatically than any other, and that is the urgent and growing threat of a changing climate." The president proudly added that since he took office the U.S. produces three times more electricity from the wind and 10 times more from the sun. How much is that? The Energy Information Administration reports that in 2013 electricity from wind power amounted to 4.13 percent and solar to 0.23 percent of supply.

The president observed that "the United States has reduced our total carbon pollution by more than any other nation on Earth." In fact, by 2012, U.S. carbon dioxide emissions were down by more than 12 percent over the 2007 peak; down to about where they were in 1994. However, emissions upticked 2 percent in 2013. While the president reiterated his pledge that the U.S. would by 2020 cut its greenhouse gas emissions 17 percent below the levels emitted in 2005, he held off making any new ones, promising that "by early next year, we will put forward our next emission target."

With China clearly in mind, President Obama declared, "We can only succeed in combating climate change if we are joined in this effort by every nation –- developed and developing alike. Nobody gets a pass."

General Secretary Ban Ki Moon had hoped to attract heads of state of most the big emitting countries to the Summit, but China's President Xi Jinping declined to come. Instead, Vice-Premier Zhang Gaoli put forward China's views at the international confab today. Like Obama before him, Zhang largely stuck to restating China's earlier pledge of cutting its carbon intensity by 40 to 45 percent by 2020 from the 2005 level. Carbon intensity is the ratio of carbon dioxide emissions per unit of gross domestic product—basically burning ever less fossil fuel to produce goods. Zhang noted that by 2013 China's carbon intensity was already down by 28.5 percent. There is plenty of room to improve: China emits almost twice as much carbon dioxide per dollar of GDP as does the United States.

Like President Obama, the Chinese vice-premier was not yet ready to reveal his country's negotiating bid just yet, stating, "We will announce post-2020 actions on climate change as soon as we can." Zhang did, however, suggest that China's future pledges with regard to its greenhouse gas emissions will aim to bring "about marked progress in reducing carbon intensity, increasing the share of non-fossil fuels and raising the forest stock, as well as the peaking of total CO2 emissions as early as possible."

On the face of it, this part of Zhang's statement – especially the part about peaking emissions—should cheer those concerned about man-made global warming. Well, maybe. In his remarks, Zhang also repeated China's dogged insistence on adherence to the United Nations Framework Convention on Climate Change. In that treaty, China and a bunch of other developing countries have no firm obligations whatsoever to do anything about their emissions. That treaty was adopted in 1992 when China's was much poorer and its emissions hovered around a third of what they are today. In other words, Zhang seems to be insisting that the world's biggest emitter should be given a "pass" with regard to making any commitments toward actual cuts in greenhouse gas emissions. Meanwhile Zhang also declared that "developed countries need to intensify emission reduction and fulfill their commitment of annual financial support of 100 billion US dollars and technology transfer to developing countries by 2020."

I plan to do a more in-depth report and analysis of what happened – and did not happen – at the U.N. Climate Summit later this week.