While accounting for different population sizes, a weakness with annual-per-capita-emissions-by-nation is that the problem of global warming has emerged because of past emissions, not just current emissions. Remember that emissions persist in the atmosphere for a long period (for a review go here). This means that the warming we are experiencing today was, in part, caused by emissions generated by human societies fifty to a hundred and even more years ago. Is it fair to look just at current emissions or should we consider historical emissions? Historical emissions allows accounting for the cumulative contribution a country has made to the problem.
The emissions that are continuing to cause global warming are rooted in the industrial revolution, a process that emerged beginning in the late 1700s in some, but not all nations. Eventually, the mechanization of production replaced human, animal, or simple hydrologic power with fossil fuels – coal, oil, and natural gas. Burning these fuels in engines, machines, and power plants in the heavily industrialized West (the US and Western Europe) has been occurring for a solid couple of centuries – contributing to the changes in the climate we are experiencing today. This trend of historically-high levels of burning fossil fuels is not found in nations of the world that were delayed in their industrialization due to colonization and other social and geopolitical forces.
The figure below illustrates countries’ and regions’ historic (1751-2017) emissions of CO2. The US alone accounts for 25% of the historic emissions, the 28 nations of the European Union account for 22% and China 12.7%. India, one of the current top 5 emitting nations accounts for just 3% of historic emissions. All the nations of Africa and South America COMBINED account for just 6% of historical emissions.
Below is an animated bar chart from Carbon Brief showing cumulative CO2emissions by country since 1750. The rise of the US over historical colonial world power, the United Kingdom, especially after WWII is clearly evident. The rise of China, particularly more recently, is also evident.
Taking historical emissions into account shows clearly that a handful of industrial powers, particularly the US and Europe are largely responsible for global warming. Determining responsibility for the cause of global warming and climate change helps determine the expected effort of a nation or its responsibility for addressing the problems that emerge from their actions.
As an individual nation, the US is a significant current contributor to global warming emissions, among larger nation-states it has the highest per capita current emissions, and historically it is the highest single-nation contributor to greenhouse gas emissions.
For a detailed mathematical accounting of the methodology for calculating historical emissions (and the subsequent to temperature increases) see the appendix of this report from Climate Analytics. Nation by nation historical contributions are more difficult (if not impossible) to measure per capita due to the changing population over time.