Historical Emissions

5 September 2019  |  BY Jeremy Moss, UNSW  |  Ethics and Exports
smoke stacks

The world is running out of time to reduce its levels of GHG emissions.

Each year the world emits around 35 Gt of CO2. Avoiding the worst effects of climate change and keeping temperature rises to 2C means we are unable to continue emitting at such a rate; we have a limited time before exhausting our ‘carbon budget’ (Rogelj et al 2016, p245).

Each country is responsible for its share of these emissions. The amount that each respective country emits is counted against its targets and what it is permitted to emit in the future.

But what about emissions produced in the recent and not-so-recent past? Should we hold countries responsible for those emissions as well? This is an important question as these ‘historical emissions’ make up a large part of the CO2 currently in the atmosphere, and so  limits what can be emitted  in the future.

Developing countries rightly point out we cannot simply focus on countries’ present emissions, particularly considering we now face the threat of climate change primarily due to the high level of historical emissions. Countries such as the U.S., Germany or the U.K. have been emitting vast quantities of GHGs for more than a hundred years.

In contrast, newly industrialised countries such as India or China have only just begun to use fossil fuels for their development. They claim that they ought to be able to use cheap, plentiful fossil fuels to lift their people out of poverty, just as wealthier countries have done.

Why should developing countries have to forego this opportunity by drastically limiting their fossil fuel use whilst countries with far greater a share of the contribution in terms of historical emissions are not taking on more of the burden? Why should their relatively young populations be disadvantaged?

This kind of argument for allocating future emission rights is often known as the ‘historical responsibility’ or ‘polluter pays’ principle. According to this principle, historically high-emitting countries should be entitled to a smaller portion of the remaining global carbon budget than historically low-emitting countries.

This principle has intuitive appeal. As an illustration, imagine your workmates had baked you a cake for your birthday, but when you all went to eat it  you found that two people had already devoured half of it. If you shared the rest, you would probably not give the ‘greedy two’ any of the remaining cake. This relies on the idea that, absenting other reasons, there is a presumption in favour of an equal distribution of this resource. In other words, we operate on the understanding that resources should be shared equally, and so, all other things being equal, early eaters should not get more cake than others just because they got there first.

Applied to the climate case, this historically high-polluting countries are less entitled than historically low-polluting countries, given they have already used up more than their ‘fair share’.

In response, historically high-emitting countries often claim that, while their historical emissions are considerable, individuals in the past were not aware of the consequences of their actions. We might say that they were ‘excusably ignorant’, since substantial and widespread awareness of climate change and its causes did not come about until relatively recently. It is often claimed that it was not until the publication of the first IPCC report in 1990 that there was widespread knowledge of the causes and consequences of climate change.

Of course, it is somewhat artificial to say that, in one moment individuals were excusably ignorant, and in the next they were not. Indeed, we did not all suddenly wake wiser and more informed on January 1st 1990! The possibility that our GHG emissions were problematically high was on the table before the IPCC report (that is, after all, why the first IPCC report was written), and probability of harm carries responsibility just as certainty does.

However, the publication of the first IPCC report does provide a clear and distinct ‘epistemic’ shift. It was the first comprehensive, detailed, impartial examination of the issue by experts; it was publicly accessible, widely reported, and cannot reasonably have escaped the notice of many decision-makers (including voters in democratic countries); and it indicated with confidence that human activity was warming the climate to such an extent that significant and swift reductions in GHG emissions would be required to avoid very harmful consequences.

Another familiar objection to holding countries responsible for historical emissions is that countries should not be held responsible for the actions of their or other people’s distant ancestors. What have the emissions produced by Australians in 1906 got to do with the responsibilities of Australians living now? It is argued that there are too many ‘weak links’ to warrant liability.

According to such objections, countries that now exist are not connected strongly enough to their former selves that emitted in the past to justify holding the former responsible for the emissions of the latter. There are a number of variations on this kind of objection.

Some appeal to the fact that many of the citizens, residents, or decision-makers responsible for past emissions are dead. There is also the distinct concern that some countries no longer exist, or have changed so significantly as to call into question the idea that they are the same moral entity. Where should fault be laid for past emissions of Yugoslavia or the Ottoman Empire?

A third concern is that some countries may not be properly governed by their residents or citizens. Can the citizens of a now democratic country that was in the past a high-emitting dictatorship legitimately be held responsible for their country’s ‘historical emissions’? If not, are we justified in limiting the emissions of that country, and thus its citizens?

So, do these kinds of objections make a difference to the degree of responsibility held by historically high emitting countries? Let’s say for argument’s sake that they do, and they at least limit the moral weight of historical emissions in assessing a nation’s relative responsibility for climate change harms. Where does that leave us?

The answer is that a principle of historical responsibility still plays a huge role in determining future emissions rights. The reason is that, at the time of writing, almost half of the total carbon emissions by fossil fuel use and cement production since 1750 has in fact been emitted since 1990. In total, 415Gt CO2 has been emitted since 1750; over 200Gt CO2 of that has been emitted since 1990 (Duus-Otterström 2014, p.449).

Further, with every year that passes without substantial action to mitigate climate change, the percentage of post-1990 emissions increases (Duus-Otterström 2014, p.449).

The inequalities in emissions produced by different countries over this time frame are also stark. Between 1990 and 2015, the U.S. emitted 38GtCO2 into the atmosphere, while India emitted 9GtC and Brazil 2.5Gt CO2 (with populations about 3.5 and 0.5 times that of the US, respectively) (WRI). Thus, not only have a high percentage of the world’s emissions occurred post 1990, they have been distributed very unequally across the globe. The US has produced 34%, the EU 28% and China a staggering 44% (WRI).

If the publication of the IPCC report in 1990 marks a turning point, then countries are not excusably ignorant about a large proportion of their emissions. It also seems likely that countries have strong enough connections to their citizens during this period for the weak links not to apply. 1990 is not that long ago, the territorial boundaries of the vast majority of nations have remained stable and relatively few governments have shifted from dictatorships to democracies.

Taking recent (post 1990) historical emissions into account in attempting to equitably divide the remaining carbon budget will mean that historically high-emitting countries are entitled to a smaller portion of remaining allowable emissions  which in turn means that they must take more aggressive steps to rapidly and significantly reduce their emissions. One consequence of having a smaller ‘cut’ is that some countries will have already used up their carbon budget.

Countries that are ‘late industrialisers’, such as China or Brazil, might claim that incorporating a principle of historical responsibility will impose on them an unfair burden, given that they had little choice but to produce substantial emissions since 1990. Recall that China has produced 44% of its emissions since 1990, a higher percentage than the US (34%) or the EU (28%) (WRI).

While we cannot escape the reality that the world’s emissions are rising at too fast a rate to allow even many developing countries to continue emitting at their present rate, there are some reasons to think that adopting the post-1990 ‘historical responsibility’ or ‘polluter pays’ principle would not unfairly burden recently industrialised countries.

First, historical responsibility is unlikely to be the only principle that should be part of how we assess and divide future emissions across the globe. Adopting only one principle of justice (in this case historical responsibility) will have plainly unfair and unrealistic implications and probably fail to account for other important issues.

Second, assuming responsibility for post-1990 emissions seems onerous or overly demanding in part due to how UNFCCC counting rules are formulated. Currently, a country’s actual emissions budget is a function of the GHG emissions produced within its territory. Yet, as has been pointed out, this neglects the fact that at least some of these emissions were produced in the manufacture of products for other countries. For example, a portion of China’s significant post-1990 emissions stem from industrial activity in supplying the US market. Some allowance might be made for such circumstances in determining the framework for the world’s carbon budget.

Not only has a large percentage of the world’s GHG emissions been produced since 1990, this occurred under clear knowledge of the dire consequences. Together, these two facts mean that the principle of historical responsibility has a powerful role to play in the division of the world’s remaining carbon budget.


Duus-Otterström, G. 2014 ‘The problem of past emissions and intergenerational debts’, Critical Review of International Social and Political Philosophy, Vol.17, No.4 pp.448-469.

Moss, J. Kath, R. ‘Historical Responsibility and the Carbon Budget’, Journal of Applied Philosophy, Vol 36/2, pp. 268-289.

Roglej et al, 2016, p245. “Variations within this range depend on the probability of staying below 2 °C and on end-of-century non-CO2 warming.”

Shui, B. Harriss, R.C. 2006 ‘The role of CO2 embodiment in US-China trade’, Energy Policy, Vol. 34, No.18, pp.4063–4068.

World Resources Institute, n.d ‘CAIT Climate Data Explorer’, Total GHG Emissions Excluding Land-Use Change and Forestry, WRI, Washington DC, USA.