The talks between President Xi Jinping and visiting US President Barack Obama in the past two days have turned out to be productive. Impressive consensuses have been reached on such topics as trade and investment, anti-terror collaboration, dispute resolution and crisis control, to name but a few.

Even by agreeing to disagree, their face-to-face communication is conducive to benign interaction between the world's two largest economies. At least it helps to reduce the tensions that have resulted from misjudgments about each other's strategic intentions. China and the US have too many mutual misunderstandings for them to be straightened out in just a couple of days.

But the real highlight of this Xi-Obama meeting was the "China-US Joint Announcement on Climate Change". This unexpected outcome on global warming is a pleasant surprise.

China and the United States, which together are said to produce around 45 percent of the world's carbon dioxide, are considered key to a global deal on reducing greenhouse gas emissions in Paris next year. But they had been at loggerheads over the principle of common but differentiated responsibilities and respective capabilities.

Now China, for the first time in history, promises to make sure its greenhouse gas emissions peak around 2030, or earlier, and to increase the proportion of non-fossil fuels in its primary energy consumption to around 20 percent by 2030. That is a huge commitment for this country of 1.3 billion people, where development carries the only hope of freeing hundreds of millions from their daily struggle for subsistence.

In another historical first, President Obama pledged to cut his country's emissions by 26 to 28 percent below its 2005 level in 2025, and to "make best efforts" to make it 28 percent. That is an ambitious goal that entails a shared political will across party lines back home.

Obama acclaimed the joint announcement as a "historic agreement" and a "major milestone in the US-China relationship". It was certainly both.

Xi has advocated that China and the US work together so their new type of major-country relationship can bring more and better benefits to the peoples of both countries and the rest of the world. That the world's two largest polluters have finally chosen to join hands and "work constructively together for the common good" will do that.

At the negotiating tables for climate change control, there is no better way than to lead by example when it comes to persuading reluctant others.

Having agreed to set such a fine example, both China and the US will find their rhetoric about climate change more convincing and persuasive in the future.