Both increase productivity, which is higher output per unit of labor input.

FORBES: Protection Does Not Create Jobs

When anticipated supply is sufficiently high, gas undercuts coal as the fuel of choice for electrical generation, which results in reduced carbon dioxide emissions, as natural gas produces only about 50% to 70% of the carbon dioxide per unit output (depending upon your metric) that coal does.

FORBES: China Talks A Green Line While The U.S. Walks One

Hu has pledged to reduce carbon intensity, or the amount of carbon emitted per unit of economic output.

CNN: Obama's China trip is high-stakes mission for environment

In 2006, the first year of the plan, the country's reduction in energy intensity, which measures energy consumption per unit of economic output, was a mere 1.23%.

FORBES: Magazine Article

America guzzles more petrol per person than any other big country, and uses more energy to produce each unit of economic output than most of its rivals.

ECONOMIST: Pump fiction | The