The INDC model of target setting reflects a compromise that allowed for maximum participation in the Paris Agreement at the expense of transparency and precision (Keohane and Oppenheimer 2016). Instead of negotiating country-level GHG targets multilaterally—as was done with the 1997 Kyoto Protocol and was attempted at the 2009 United Nations climate conference in Copenhagen—governments selected their own, nationally determined, contributions to addressing climate change before meeting in Paris in December 2015. However, many states had reservations about accepting costly mitigation commitments given that there was uncertainty about their counterparts’ willingness to contribute as well. Therefore, while the 2014 Lima climate conference outcome document invited parties to include “quantifiable information on the reference point (including, as appropriate, a base year), time frames and/or periods for implementation, scope and coverage, planning processes, assumptions and methodological approaches including those for estimating and accounting for anthropogenic greenhouse gas emissions and, as appropriate, removals,” this information was not mandatory (UNFCCC 2014, para. 14). Governments interpreted this guidance loosely and submitted INDCs that vary tremendously in their content, detail, as well as ambition.
Since domestic GHG mitigation imposes costs in the present and creates uncertain future benefits, political leaders must navigate difficult intertemporal and distributive bargains (Jacobs 2011). In contexts where domestic publics are more aware of climate change, politicians have incentives to appear to be taking responsible action to mitigate risks, while remaining sensitive to the political risks if policy reforms are costly (Harrison and Sundstrom 2010). When policymakers have access to complex policy instruments, such as with the largely unstructured INDC system, these incentives may lead actors to increase the complexity of policy measures rather than to match public preferences for policy outcomes (Kono 2006). Similarly, national governments may engage in “symbolic regulation” that seeks to reassure domestic regulatory advocates, without providing the actual policy reforms advocates desire (Peacock 2018). In sum, recent political science research suggests that when governments face pressure to impose new regulations but also fear the costs of policy reforms, they may adopt policies that mask their true impacts from public audiences.
In climate mitigation, this obfuscation may take the form of a divergence between stated GHG emissions reductions and actual reductions. If such a divergence exists, then using the headline percentage emissions reduction to measure GHG emissions reductions—as Drummond et al. (2018) do—may be uninformative about actual emissions reductions. Governments may pledge ambitious sounding policy targets to appear engaged, while cushioning the impact of such policies by changing the terms to minimize the actual emissions reductions associated with a stated percentage point change. I now explain how governments could use the vagueness of the INDC design to disguise their true GHG mitigation commitments.
The lack of common reporting requirements has led the INDCs to vary along many dimensions and the documents therefore require further interpretation to make them comparable. The World Resources Institute has undertaken an exhaustive data collection and synthesis project on the INDCs (WRI 2016; Ross et al. 2016). Political scientists have already begun analyzing this data (Tobin et al. 2018). For the purposes of this paper, I outline the different categories of targets that countries adopted in their INDCs and use these to explain how different types of targets create opportunities for headline percentage reductions to diverge from actual emissions reductions. Interested readers should consult Ross et al. (2016), Climate Watch (2016), and Tobin et al. (2018) for more in-depth treatments of target types.
INDCs may contain three types of non-mutually exclusive climate targets. First, countries may declare policy goals that have mitigation co-benefits, such as increasing energy efficiency by 20%. Second, they may announce specific mitigation of adaption actions without linking these explicitly to GHG emissions flows, such as improving coastal management to reduce flood risk. Finally, countries may express economy-wide GHG emissions reduction targets. The above non-GHG targets and actions targets cannot be compared directly with GHG targets without a host of non-trivial modelling decisions. Ultimately, not all countries have directly comparable targets, which may lead to misleading inferences for the raw data.
Economy-wide GHG emissions reductions targets can also be expressed in different ways. Base year targets specify GHG targets in terms of reductions from GHG emissions in a historical base year. This GHG target format is adopted by Annex 1, industrialized countries, as well as a few developed countries. As noted above, Canada has pledged to reduce GHG emissions by 30% from 2005 GHG emissions levels by 2030, while Russia will cut by 25–30% from 1990 GHG emissions levels by 2030. Canada and Russia’s targets may be similar in headline percentages (30% and 25–30%, respectively), but the choice of base years (2005 and 1990, respectively) informs the size of a percentage reduction. Russia’s emissions fell substantially during its prolonged recession at the end of the Cold War, but have been very stable since the mid-1990s and never recovered to their earlier levels. In this situation, choosing an earlier base year makes a percentage reduction seem larger than choosing a later base year. Canada’s emissions trajectory is reversed, as its emissions have risen consistently over the past twenty years, making percentage reductions seem larger if a later base year is chosen. Governments may choose base years strategically to make an emissions reduction seem larger and so they ought to be standardized with common base years.
For base year targets, country i’s compliance GHG emissions level (Ci) is given by:
$$ C_{i} = \text{GHG}_{i,t^{\prime}} \times S_{i}, $$
(1)
where GHGi,t refers to country i’s GHG emissions in year t, \(t^{\prime }\) denotes this year as a country’s chosen reference year, and Si denotes a country’s stated (or nominal) percentage GHG emissions reduction. Countries’ targets can be expressed as percentage reductions from different historical reference years (t < 2015) by re-arranging the equation. The choice of base year has enormous consequences for the headline emissions reduction target. While a variety of factors may influence a government’s choice of base year, such as choosing round numbers or the same year as their peers, governments may also select base years near the peak of their observed historical emissions to make any percentage reduction seem larger. Of the 59 countries with base year targets in the Paris Agreement, 44.1% of countries selected one of the three most favourable years as their base year (see Fig. 5 in the supplementary information).
Scenario targets specify emissions reductions from a hypothetical “business as usual” (BAU) GHG emissions growth scenario. This type of target is common among non-Annex 1, developing countries. For example, Brazil announced its intention to cut GHG emissions by 37% relative to BAU levels by 2025. However, governments are not always transparent about how they calculate BAU emissions growth and some countries forecast much quicker GHG growth in the 2015–2030 period than in the previous 20 years. The BAU forecasts are not simple extrapolations of historical growth rates. Just as countries may select base years opportunistically, they may also forecast high exceptionally BAU emissions growth to make a nominal emissions cut seem larger. Furthermore, some countries do not specify a future BAU emissions level that they intend to cut emissions from, thereby making their targets fundamentally non-quantifiable. Without an emissions reference point, it will not be possible to assess whether actual GHG emissions in 2030 are below “BAU” levels by the target amount.
For base year targets, countries select t < 2015 to denote that reference GHG emissions level are observed in the past. For scenario targets, the reference GHG emissions level is forecasted as a future emissions level under BAU, GHGi,t= 2030. When a scenario target articulates this future emissions level explicitly, a country’s compliance GHG emissions level is given by the following equation:
$$ C_{i} = \text{GHG}_{i,t=2030} \times S_{i} $$
(2)
Knowing Ci and GHGi,t, scenario targets can be re-arranged algebraically to be expressed as percentage changes from any specified historical base year, t < 2015.
Countries may also index their GHG targets to another variable, such as national gross domestic product (GDP) or population. These intensity targets require forecasting the index variable (i.e., GDP or population). A 30% reduction in the emissions intensity of GDP is not the same as a 30% reduction in absolute emissions even if both can be evaluated at the expiry of the Paris Agreement. Trajectory targets outline intentions to peak emissions by a certain year. However, if no hard cap on absolute GHG emissions is given to this peaking level, then peaking cannot be compared with other targets ex ante and will require many additional time periods after the target year to verify that emissions have actually peaked.
The INDC design allowed countries high levels of discretion in drafting their Paris pledges. This led to wide variation in the form and substance of the documents. Comparing GHG emissions reductions targets across countries requires knowing the percentage reduction, the reference absolute emissions level from which emissions are to be cut, the target year, and historical emissions levels. The headline percentage reduction target is uninformative without this complementary information, which may be omitted by governments or manipulate to inflate perceptions of their mitigation contributions. In the next section, I outline two alternative measures of countries’ targets that are less sensitive to opportunistic choice of reference levels and that allow all countries with quantifiable GHG targets to be compared on a common scale.