More on CO2

Further reflections on Industrial (and heating) CO2 Emissions in UK, USA, and World-1750-1900. (See also note in Errata.)

As the science gets better, our understanding of the history of CO2 emissions should improve. I say “should” because the enormous cutbacks in climate science in the United States poses extraordinary risks. Quite literally, global warming and scientific research are headed in opposite directions.

The basic point I make in The Killing Age is pretty simple and mostly uncontroversial: the UK and the USA accounted for the lion’s share of CO2 emissions in the period 1750-1900. The challenge is how best to understand the data.

Here I want to reflect and offer some additional information and insights. The first thing to remember is that the important point is to identify general patterns. It is easy to get hung up in debates over precise numbers, which can be all over the place.  Nonetheless, I want to add some more details, if only to explain how I got to various estimates. When I was doing my research, I was interested in the transition to fossil fuels; this includes both industry as well as, for example, burning coal to heat homes. (For one article that discusses estimates, see Robbie M. Andrew, “A Comparison of estimates of global carbon dioxide emissions from fossil carbon sources,” in Earth Systems Science Data, 12, 2 (2020): 1437-65.) There is also another article that may be of help: Pierre Friedlingstein et al, “Global Carbon Budget,” also published in Earth Systems Science Data, 17, 3, 14 March 2025. You will note that there a wee little bit of slippage; the  authors reference 1750 but mostly use 1850 as the baseline for the “historical period.”

I used multiple sources during my research, one result being that not everything adds up. For example I used Statista estimates of 45.1 billion pounds of total emissions, with 44.8 billion coming from the UK and USA. This yields a result of .9933, or 99.33%. The website seems to have changed, however, and it seems that I made a significant mistake is estimating cumulative totals and cumulative per capita totals. At Statista, the downloaded EXCEL file has cumulative totals from 1750-2023. Here the global total is 1353.30. The total for the USA is 431.90, or about 32%. Adding the UK increases things to about 38%.  Of course, China and Russia are major emitters, followed by countries like Japan and India. These were all relatively late newcomers to the emissions picture.

Other estimates move this figure for the period 1750-1900 down to about 70%, so there is a considerable range here. Much depends on total emissions, and that number is something of a moving target. In other words, different people are measuring different things, and this produces lots of confusion (just burning coal? just industry, and how to define industry? and so on). Other data on “distribution of cumulative carbon dioxide in  Ourworldindata has UK/USA at 100% in 1750 (with USA at 0); 99.32% in 1800; 81.76% in 1850, and 60% in 1900. The time-weighted mean comes out to 85.27%.

Another way of approaching this data is to look at emissions per capita. (This is where I sowed confusion!) Here the percentage is about 95.95%. The yearly average for UK and USA is 6.95185421 t/person, while the world figure is 0.29312 t/person. Since the world figure also includes UK and USA, that 95.95% figure is likely highly if we took these two countries out of the equation. When you subtract the USA and UK populations from the world population, the figure goes even higher. I have not made further adjustments for slaves and indigenous peoples in the USA. I have included this raw data as well as a chart. co-emissions-per-capita ukusaworld 

Finally, here are two open access files taken from the Friedlingstein et al article. the PDF is easily downloadable. The CVS file is massive. Please be careful as it might overwhelm your system, as it has mine a few times. You can find USA at lines 53938-54036! For webpage PRIMAP-hist_v2.7_updated_figures

Guetschow_et_al_2025a-PRIMAP-hist_v2.7_final_no_extrap_no_rounding_22-Aug-2025