Evolution of Top and Bottom CO2 emitters 1961-2010

Generally, some of the developed countries (mainly the US) claim that it is the developing world responsible for the current state of emissions and they should be the one held responsible and not the developed countries. In fact, this was one of the reasons mentioned by President Trump for the US's withdrawal from the Paris Climate treaty. Additionally, there have been discussions about growth-emission connections and inequalities in emissions. Therefore, to get some insight into the reality of this argumentation, I analyzed 90 countries to understand how CO2 emissions have evolved over time and who's responsible and how much.

I collected data on CO2 per capita emissions (pce) for all the countries from 1961-2010. Due to data availability issues, I selected 90 countries amongst them for whom annual data was available for the given period. Because my objective was to analyze the inequalities in emissions and their evolution over time, it was necessary for me to track them inter-temporally first. To make it tractable, I took a decadal average of emissions for each country i.e. 1961-70, 1971-80 and so on. Then I proceeded by arranging the countries in the manner to get top-25 and bottom-50 polluters. In order to get a glimpse of the GDP growth connection of emissions, I also collected the data and calculated their decadal averaged growth rates for each country. Now, since the cross-section had 90 countries, it wasn't possible to track each country. To make cross-section tractable, I clubbed top polluters in a group of 5, while clubbing bottom polluters in a group of 10. This was done because countries amongst top had large variations, thus I clubbed them in smaller groups, while those in the bottom had smaller variations, thus larger groups. Subsequently, the growth rates were calculated for the respective bins. I also calculated the fraction of total emissions that each of the bin account for. I have also mentioned the cut-off pce for each bin, which is basically the per-capita emission of the bottom-most country in each bin. This would enable us to see how each of the bin's evolved. The cut-off emission means that every country in that particular bin has emission per capita between more than the cut-off mentioned for that bin and below the cut-off for the bin above it. In the end, total pce (decadal) by all the 90 countries is mentioned as well. The data is tabulated below.

World:

The 70s witnessed a large boom in emissions per capita due to the advent of the fuel-based economy. However, since the 80s, consequent increases in per capita emissions can be seen, which is a little worrying. (Appendix - A3)

Top emitters: (Appendix-A1)

The total fraction of emissions from combined top-25 countries has declined since the 60s from 84% to 74%, i.e. by 10 percentage points (pp). However, still, these countries account for 3/4th of the pce

1/3rd of the pce amongst top-25 countries comes from top-5 polluters

Within the top 25 countries, (Appendix - A4)

the fraction of the world's emissions has declined for top-10 countries only
For 11-15 biggest polluters, the fraction followed an inverted U curve and has settled at the same level
The latter countries, that is, 16-25, their fraction of the world's emissions have increased

In absolute terms, pce has increased in all the bins. Thus, the reduced fraction for top-10 countries might be because the rest of the world's pce rose at a higher rate. The behaviour of 16-25 countries even supports this argument. (Appendix - A5)
The cut-off to make into top-5 biggest emitters have increased over time. This hints at growing inequality of pce within top-25 emitters. This also suggests different levels of convergence within the top-25 band

For other countries, that is, 6-25, the cut-off has only slightly increased (relatively speaking) (Appendix - A6)

Amongst top pce emitters, it can be observed that most of them belong to the high-income group

Bottom emitters: (Appendix-A2)

The total fraction of emissions from combined bottom-50 countries has increased since the 60s from 6% to 11%, i.e. by 5 percentage points (pp). However, still, combined 50 countries account for only 1/10th of the pce

Bottom-most 35 countries account for 1/2 of this pollution while the 15 above them account for rest 1/2.

Within the bottom-50 countries, (Appendix - A7)

the fraction of the world's emissions have remained constant for bottom-most 30 countries
For countries in the middle, that is, 30-50 from the bottom, their fraction to world's emission have increased slightly

In absolute terms, pce has increased in all the bins but to different extents: (Appendix - A8)

For bottom-most 20 countries, even the absolute pce hasn't increased at all
For countries between 20-30 (from the bottom), absolute pce has increased marginally
Here too the increment has come from the middle ranged countries, that is, countries between 30-50 (from the bottom). The increments were significant with countries between 30-40 (from the bottom) showing risen pce by almost 3 times and countries between 40-50 (from the bottom) showing the rise by almost 2 times

The cut-off to make into bottom-50 emitters have increased over time but show differences. (Appendix - A9)

The cut-off for the bottom-most 20 countries hasn't changed at all.
For the countries lying between 20-30 (from the bottom), it has increased but slightly
For the countries lying in the middle, that is, between 30-50 (from the bottom), the cut-off increased significantly, that is, more than twice
This hints at growing inequality of pce within bottom-50 emitters and it seems much stronger than the once seen amongst top-25 emitters

What can be understood from this is:

Developed or high-income nations are responsible for higher pce levels
The fast growth in pce presently is coming from middle-income or mid-level countries (pollution wise). This is possible because they are growing at a faster pace. Although it is true that these countries start investing adopt sustainable pathways but I believe it would be wrong to put the entire blame on these economies away from developed nations. This is because unlike high-income countries, these countries have relatively larger poor population to serve. Having said that, this should not become an excuse for the low-income countries to refrain from sustainable activities but I believe that the high-income countries need to take an initiative.
The low-income countries or the ones where pce are extremely low are stagnating and have a negligible contribution to the growth of pce or fraction of the world's emissions.

Similar to some of the major reasons which are leading to the anti-globalization wave, like lack of compensation to the fraction of the population who lose to the competition, the same is causing countries to back off from the climate treaties. Rising inequalities in pce should be taken into account while making climate policies and everyone needs to understand them.

Click here to get the data file

Appendix - A1.