As a former prime minister of Australia, I understand something of the political costs leaders must bear in aiming to reconcile the long-term interests of the planet with short-term national interests.

In the cynical world of politics it is important, just occasionally, to give credit where it is due. The commitments on carbon emissions announced on Wednesday by President Barack Obama of the US and President Xi Jinping of China, supported by the significant diplomacy of Secretary of State John Kerry, are both environmentally substantive and politically influential. Between them, these countries account for 44 per cent of global carbon emissions – a share that is still rising.

China's political, economic and foreign policy over the next decade is not only fundamental to the country itself, but also to the wider Asia-Pacific region and – increasingly -- the world beyond.

China already represents 16 percent of global gross domestic product (GDP), rising to 28 percent by 2030. China is also by far the world's largest emitter of greenhouse gases. Furthermore, continued maritime boundary disputes in both the East and South China seas are a significant continuing factor in the region's underlining strategic instability. How China deals with each of these challenges is therefore of significance to us all.