The areas of the wedges, and the numbers beside the country/region name, represent total CO2e emissions, in Megatonnes(Mt)/year reported for 2006. The angle of the wedge represents the total population (2007 figures). The radius represents the percapita emissions.

The wedges are arranged by per-capita CO2 emissions.

The emissions numbers are from the Energy Information Administration (EIA) and the population numbers are from the Population Reference Bureau.

Notes:

• Total emissions for China are slightly less than the US even though their population is more than 4 times as great (China: 1,318 million. US: 302 million).
• Canada's 2006 percapita emissions are the second highest (behind the US). More recent estimates put Canada at the top of the list.
• The grey circle represents average global percapita emissions (3.8 tonnes) for the year 2000.

The numbers used in the chart are as follows:

The inspiration for this chart is the famous coxcomb chart that was designed by Florence Nightingale to represent the causes of deaths of British soldiers during the Crimean war. This chart was developed at the suggestion of my friend, Professor Lynn McDonald, editor of the Collected Works of Florence Nightingale.