Previous post in this series:
(1) The exceedingly small but fully real effects of my greenhouse gas emissions
Many assume that individuals are not responsible for climate change and do not have any agency in tackling it. In this series of posts, I argue that this view is mistaken. The previous post concluded that individual emissions have an exceedingly small but fully real effect in that they increase the risk that vulnerable people suffer from climate change harms.
Extending this conclusion, in this post, I will address (and reject) the assumptions that individual emissions are neither necessary nor sufficient to cause climate change.
Walter Sinnott-Armstrong assumes that global warming will not occur unless lots of other people also expel greenhouse gases: an individual act is neither sufficient nor necessary to cause global warming. (1) These claims are two sides of the same coin: both are based on the characterisation of climate change as a threshold phenomenon. The claim that individual emissions are insufficient to produce harm assumes that emissions cause harm only after their accumulation exceeds a certain threshold. The claim that individual emissions are unnecessary to cause harm starts from the assumption that the accumulation of greenhouse gases already exceeds the threshold, and thus that climate change will occur anyway, whether or not an individual emits greenhouse gases.
I believe the characterisation of climate change as a threshold phenomenon is misleading – and that, therefore, Sinnott-Armstrongs conclusion that individual emitters cannot be held responsibility for causing climate change harms is misguided. I will argue this first by briefly showing that the threshold model has some implausible implications, and second by investigating different answers to the question as to where exactly the threshold is situated.
The greenhouse gas molecule that crosses the threshold
To me, the threshold model appears to imply that greenhouse gases emissions would be no problem at all, until, at some moment in time, there is one especially insidious greenhouse gas molecule that represents the last straw and all of a sudden causes climate change. The claim that individual emissions are neither sufficient nor necessary to cause climate change seems to imply that no emissions cause harm, but for the one greenhouse gas molecule crossing the threshold.
This clearly is not how climate change works. First, the threshold model treats earlier emissions (below the threshold) as insignificant, because they supposedly are insufficient to cause climate change. However, within the threshold model, it is clear that the harmful effects would not have obtained without all previous contributions. In real life climate change, historical emissions have already caused harm (see below). Second, once the threshold is exceeded, further emissions apparently do not matter either, supposedly because climate change happens anyway. This is misleading because further emissions exacerbate climate change and increase its harmful effects.
In my view, this quick argument already shows the inaccuracy of the threshold model: anthropogenic climate change is rather a gradual, additive process (although it might also include some abrupt transitions), exacerbated by each emission of greenhouse gases.
Setting the threshold
For the sake of the argument, suppose, however, for a moment that climate change is a threshold phenomenon. What would that threshold be?
The international community has accepted an increase in global temperatures of 2°C above pre-industrial levels as the threshold of dangerous interference with the climate system. (2) Does it make sense to put the threshold of harm at a level of greenhouse gas concentration in the atmosphere corresponding to this target? One problem here is that the global inaction and sustained annual growth in greenhouse gas emissions make it increasingly unlikely that humanity will succeed in curtailing the increase in global temperature below 2°C. From this perspective, each individual emission increases the likelihood that this threshold will be crossed, thus increasing the likelihood of dangerous climate change.
Moreover, the 2°C target is in fact arbitrary, politically agreed upon, and criticised by climate science (3) and ethics (4). For example, even a temperature increase below 2°C puts some unique and threatened systems (including Arctic sea ice and coral reefs) at risk. In addition, the Alliance of Small Island States has declared that global warming must be kept well below 1,5°C, since these states are especially vulnerable to and already experiencing the adversities of climate change. (5)
A related way of determining the threshold would refer to the critical thresholds (or tipping points) of the Earth system, beyond which abrupt or irreversible climatic changes will ensue. For example, by defrosting the permafrost, global warming might trigger the release of huge amounts of carbon, which will accelerate further warming and climate change. However, there is much remaining uncertainty and the Intergovernmental Panel on Climate Change has low confidence in the occurrence of abrupt changes in the 21st century. (6)
Most importantly, even below such tipping points or the 2°C threshold, global warming results in climate change harms. We currently observe an increase of global temperatures of about 0.85°C since 1880. This warming has already led to significant impacts on human life today. For example, the World Health Organisation has estimated that climate change was already responsible for 3% of diarrhoea, 3% of malaria and 3.8% of dengue fever deaths worldwide in 2004. The total mortality attributable to climate change was about 141,000 deaths in 2004, of which 85% were child deaths. (7) These numbers are rapidly increasing as climate change is continuing to exacerbate.
The only relevant threshold in climate change appears to be the point at which anthropogenic emissions started disrupting the balance between greenhouse gas sources and sinks. This threshold would be situated at the start of the Industrial Revolution, when the enormous expansion in the use of fossil fuels massively increased humanity’s impact on the Earth System. (8) If this is true, then those who maintain that climate change is a threshold case should accept that the only relevant threshold in climate change has already been exceeded more than 200 years ago.
Individual additions to climate change harms
I conclude that, although they may only have an exceedingly small effect, individual greenhouse gas emissions are sufficient to increase the risk that vulnerable people suffer from climate change harms. Each emission also necessarily exacerbates this process (except, possibly, when technologies to extract greenhouse gases from the atmosphere become practically available).
My point is not to deny that climate change is a problem of collective responsibility: climate change has become such a large problem because so many individual greenhouse gas emissions accumulated in the atmosphere. My point is rather that we should resist the temptation to dodge all individual responsibility by hiding behind some complicated model of collective responsibility. Individual emitters should accept responsibility for the exceedingly small but fully real effect their greenhouse gases have.
Nonetheless, the assumption that individual actions make no difference also permeates the discussion about the responsibilities of individuals in tackling climate change. This will be addressed in the following posts.
Go to the following posts in this series:
(3) Unilateral duties to reduce greenhouse gases or promotional duties?
(4) The agency of individuals and households
(1) Walter Sinnott-Armstrong, ‘It’s not my Fault: Global Warming and Individual Moral Obligations’, in W. Sinnott-Armstrong and R. Howarth (eds.), Perspectives on Climate Change: Science, Economics, Politics, Ethics (Amsterdam: Elsevier, 2005), pp. 285-307, at p. 289.
(2) See UNFCCC, Report of the Conference of the Parties on its Fifteenth Session, Held in Copenhagen from 7 to 19 December 2009 (2009). http://unfccc.int/resource/docs/2009/cop15/eng/11a01.pdf, paragraph 1.
(3) Samuel Randalls, ‘History of the 2°C climate target’, Wiley Interdisciplinary Reviews: Climate Change 1 (2010), pp. 598-605.
(4) Since the 2°C threshold is a politically agreed upon target, we should take into account the global context of large inequalities, as well as the inverse relation between responsibility and vulnerability. Whereas rich and powerful societies (who have polluted most) are disinclined to adopt a stringent target because this would require more costly actions from them, poor societies and people suffer most from climate change harms.
(5) AOSIS (2012), Alliance of Small Island States Leaders’ Declaration, 2012, http://aosis.org/wp-content/uploads/2012/10/2012-AOSIS-Leaders-Declaration.pdf. The AOSIS repeats this pledge for the climate negotiations in Paris in December 2015: http://aosis.org/small-islands-propose-below-1-5%CB%9Ac-global-goal-for-paris-agreement/.
(6) IPCC, Climate Change 2013: The Physical Science Basis. Contribution of Working Group 1 to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (New York: Cambridge University Press, 2013), http://www.climatechange2013.org/images/report/WG1AR5_ALL_FINAL.pdf, pp. 1114-19.
(7) WHO, Global Health Risks. Mortality and Burden of Disease Attributable to Selected Major Risks (Geneva: WHO, 2009). http://www.who.int/healthinfo/global_burden_disease/GlobalHealthRisks_report_full.pdf?ua=1, pp. 24, 50.
(8) Specifically referring to the increased use of fossil fuels and the accumulation of carbon dioxide in the atmosphere, Earth System scientists situate the onset of the Anthropocene – the current geological epoch in which human activity has become the main driver of global environmental change – in the early stages of the Industrial Revolution. See Paul Crutzen and Eugene Stoermer, ‘The “Anthropocene”’, IGBP Newsletter 41 (2000), pp. 17-18; and Will Steffen et al., ‘The Anthropocene: Are humans now overwhelming the great forces of nature?’ Ambio 36 (2007), pp. 614-621, at 616.