Among the sinews of superpower strength in the 21st century, maximum energy self-sufficiency will be critical as nations jostle to secure supplies of oil and natural gas, as well as food, water and minerals.

This contest for power and influence will take place in a world with many more people and one that is increasingly vulnerable to adverse climate change.

By this measure, how will China shape up against the United States, which became the unchallenged global leader in the second half of the 1900s but is widely expected to be surpassed by East Asia's re-energized giant this century?