Those who believe that man-made greenhouse gases are responsible for global warming are also firm in the conviction that it was caused dominantly by CO2 emissions from the developed countries (inset). However, a little-known analysis from the United Nations Framework Convention on Climate Change (UNFCCC), concludes that greenhouse gas emissions from the developed countries in fact caused significantly less than half of the global warming through 2000. In this post I briefly review this analysis and its implications.
The analysis in question was performed in 2007 by the MATCH (Modelling and Assessment of Contributions to Climate Change) Group at the behest of the UNFCCC, the 1992 ageement that underpins the Kyoto and Paris Agreements. MATCH performed the analysis by compiling a data base of greenhouse gas emissions (CO2, methane and nitrous oxide) from various countries and regions, including emissions from wood-burning, deforestation and agriculture, and by running the emissions through climate models to see how much warming each country/region had generated. The results were summarized on this pie chart:
And a very interesting pie chart it is too. Assuming that the sum of the contributions from the USA, OECD Europe, Oceania (Australia and New Zealand), Japan and Canada represents the warming contribution of the developed countries we find that these countries were responsible for only 41% of the global temperature increase between 1890 and 2000. The remaining 59% was caused by emissions from Latin America, Africa, the Middle East and Asia less Japan, which with the exception of Singapore and arguably South Korea include all the world’s developing countries, along with the Former Soviet Union and East European countries, which at the time had nowhere near reached developed country income levels and mostly still haven’t.
The MATCH report broadly confirms this percentage split (note that the findings are “robust” and that “long-lived greenhouse gases” presumably do not include methane):
This paper finds that the relative contributions of different nations to global climate change— attributing only emissions of long-lived greenhouse gases—are robust, despite the varying model complexity and differences in calculated absolute changes. For the default calculations, the average calculated contributions to the global mean surface temperature increase in 2000 are about 40% from OECD90, 14% from Eastern Europe and Former Soviet Union, 24% from Asia and 22% from Africa, Latin America and the Middle East.
The OECD90 is a mix of 36 countries, dependences and islands that includes the USA, Canada and the Western European democracies plus one country that shouldn’t be there (Turkey). It does not include Australia, New Zealand and Japan. Adding the 5% contribution from these countries shown on the pie chart gives an approximate 45/55 developed/developing country split when methane emissions, most of which come from the developing countries, are excluded.
But that was the position in 2000. What has happened since then? Data on total greenhouse gas emissions by country and region are not readily available so we have to look at CO2 emissions. Figure 1 shows BP’s estimates of annual CO2 emissions between 1965 and 2015, taken from the 2016 Statistical Review, for the developed countries, China and the other developing countries. The estimates do not include CO2 emissions from wood burning and deforestation and also do not include methane and nitrous oxide, so they will underestimate the contribution of developing countries to total greenhouse gas emissions:
Figure 1: CO2 emissions from the developed countries, China and the other developing countries, 1965-2015. According to BP they “reflect only those through consumption of oil, gas and coal for combustion related activities” and “do not allow for any carbon that is sequestered, for other sources of carbon emissions, or for emissions of other greenhouse gases”.
Developed country CO2 emissions decreased marginally between 2000 and 2015 while developing country CO2 emissions, driven largely by China, increased by 80%. The developed countries accounted for slightly over half of the world’s CO2 emissions in 2000 but less than a third in 2015. It’s impossible to make a firm estimate but it’s reasonable to suppose on the basis of these results that if the MATCH group were to update its results to 2015 it would find that the developed countries have caused less than 40% of the global warming to date and the developing countries more than 60%.
Another notable feature of Figure 1 is that it shows no sign of any appreciable carbon leakage from the developed countries to China or the other developing countries. China’s explosive emissions growth began in 2002 but developed country emissions continued to grow through 2005 and did not begin to decrease until the global recession of 2008-9 (which cut annual global CO2 emissions by about 2 billion tonnes below what they would otherwise have been, a number roughly equal to the combined annual emissions of Germany, France, Italy, Spain and the UK. This is more proof, if any were needed after the breakup of the Soviet Union in the early 1990s, that economic collapse is the best way to cut emissions.) And China can hardly claim that it was unaware of the potential impacts of its actions on global temperatures. Its emissions began to skyrocket in the year it ratified the Kyoto Protocol:
Figure 2: China’s CO2 emissions, 1965-2015
And now China is regarded as a world leader in the fight against climate change. Amazing how short human memories are.
So where does this leave us? I venture to suggest that much of what has so far been agreed at climate conferences has been a result of the guilt complex suffered by the developed country delegates, who believing that they caused global warming felt compelled to take the lead in fixing it. (Kyoto, where only the developed countries committed to anything resembling meaningful emissions cuts while everyone else got a free ride, is an example.) Yet here we have data from the UNFCCC – which started the blame game – disputing this conclusion. One wonders what might have changed if the results of the MATCH study had been widely publicized, which for obvious reasons they weren’t.
And there is of course another potential contributor to global warming that lets both the developed and the developing nations off the hook – the forces of nature, about which we can do little except react.