There are many different ways to compare national responsibility for climate change.
These include current emissions – which can be viewed in absolute figures or on a per capita basis – as well as historical emissions and the carbon footprint of consumption, including imported goods.
There's also the question of whether you include deforestation, or even the extraction of fossil fuels. The simplest and most common way to compare the emissions of countries is to add up all the fossil fuels burned and cement produced in each nation and convert that into CO2.
Reliable data isn't available, but as of 2005, the top 10 emitters as measured in total greenhouse gases looked like this: 1.
When these are included, the figures change considerably, with countries such as Brazil and Indonesia shooting up the list due to emissions caused by deforestation. The US tops the list by a wide margin – though Chinese emissions have risen significantly since these data were assembled.
Saudi Arabia: 464 MT or 1.4%See more countries The problem with focusing purely on CO2 from burning fossil fuels is that it ignores other greenhouse gases and non-fossil-fuel sources of CO2. The following figures from the World Resources Institute show the top 10 nations as measured by their cumulative emissions between 18.
The tricky question of historical responsibility is one of the key tensions in the process of negotiating a global climate deal.
Since carbon dioxide added to the atmosphere can stay there for centuries, historical emissions are just as important – or even more important – than current emissions.
Here's a selection of countries and their per-person CO2 emissions from fossil fuels and cement, as of 2010: Qatar: 36.9 tonnes United States: 17.3 tonnes Australia: 17.0 tonnes Russia: 11.6 tonnes Germany: 9.3 tonnes UK: 7.8 tonnes China: 5.4 tonnes World average: 4.5 tonnes India: 1.4 tonnes Africa average: 0.9 tonnes Ethiopia: 0.1 tonnes See all countries As with national emissions, this list would look different if all greenhouse gases were included.
From this perspective, the list is topped by small countries with energy-intensive industries such as Qatar and Bahrain, and the large developing nations such as India and China look significantly less polluting.
To get a more meaningful picture, it's essential also to consider emissions on a per-person basis.
Mexico: 696 MT or 1.6%See all countries (free registration required) Comparing nations can be misleading, given their vastly varied sizes and populations.