Counting the deaths prevented by decarbonisation: A historical analysis


While there is general consensus that renewable energy technologies can make great positive contributions towards achieving the 2015 Paris Agreement, there are associated externalities that follow the adoption of low-carbon technologies (i.e. nuclear, hydro, solar, wind, geothermal and biomass) in the transition from a fossil fuel dominated energy system. Very few works exist, if any, that comprehensively assess the positive benefits and associated externalities (i.e. mortality and emissions) of such a transition. Our recent paper, The positive externalities of decarbonization: Quantifying the avoided deaths and displaced greenhouse gas emissions from renewable energy and nuclear power, takes a historical view of two associated externalities of energy systems – deaths and emissions between 2000 – 2020  – and uses the results to analyse 10 possible future pathways (see Figure 1) between 2021 – 2040.

Figure 1 presents an overview of 10 possible future pathways that involve varying combinations and suggested possible constitution of the existing energy systems involving single or multiple regime change. For instance, scenario 1 (Sce-1) depicts oil, gas and coal being replaced with nuclear with renewables and hydro remaining business as usual (BAU). Similarly, scenario 10 (Sce-10) depicts oil, gas and coal remaining BAU with nuclear replacing renewables and hydro. These options will offer varying mortality and emissions contributions and can help planners and policy makers determine how best decarbonisation on a global scale can be achieved in an equitable and just manner.

As the world gets set for another committee of parties (COP) meeting – COP 26 in November 2021, our results emphasise the need for urgency amongst planners, policy makers and governments at all levels towards accelerating efforts that can catalyse the proliferation and uptake of renewables in diversifying our fossil dominated energy system.

Historical quantification of externalities – two decades of avoidable casualties

Between the US, China, India and the EU, we computed over 42.2 million deaths and 1,120 GtCO2 of GHG emissions as the associated externalities from 2000 – 2020 based on -existing energy systems. The share of each case study of the computed deaths/emissions is as follows: US (7 million/340 GtCO2), China (27.8 million/440 GtCO2), India (2.5 million/99.1 GtCO2) and EU (4.9 million/242 GtCO2). Disaggregating the associated deaths by sources showed that coal, oil and gas contributed 99.7% of the associated deaths and were responsible for 99.3% of GHG emissions during this period.

While this period may have been lost in terms of potential contribution to reductions in GHG emissions and avoided deaths, two results from our scenario analysis stand out. First, we computed that barring installation and operations costs, about 42 million deaths and 1,098 GtCO2 of GHG emissions could have been avoided had all fossil-based sources (coal, natural gas and oil) been replaced with hydropower.

Figure 1: Scenarios, substitutes and replacement description

Though past, our results evidence that the majority of associated mortalities associated with the pre-existing energy systems may have been avoidable. It might perhaps be useful to understand at what monetary cost to national and regional governments (in terms of capital and operational expenditure) these deaths may have occurred.

Future quantification of externalities – two decades too small

Following from the historical analysis of avoidable deaths and emissions, and the multiplicity of climate change events and accords world over – all in attempts at halting the pace of environmental degradation and mortalities associated with our energy-intense clime – one may perhaps be justified believing that lessons are indeed being learnt.

Unfortunately, when we analyse current energy systems and compute the corresponding mortalities and GHG emissions, worsening results are being projected if business-as-usual (BAU) configurations are maintained. In our paper, we compute that cumulative BAU deaths and emissions are projected to reach 47.3 million and 1,318 GtCO2 of GHG respectively between 2021 – 2040.

When we disaggregate this result by country, we observe that while significant reductions are being obtained in the US (24%) and the EU (31%), these savings in avoided mortalities are being eroded by increases in China (14%) and India (177%). In similar vein, emissions savings in the US (13%) and the EU (27%) are being lost to increases from China (31%) and India (173%).

What does this imply?

Taking a technological perspective of the projected results, two things immediately stand out. First, the dominant primary energy sources (coal, natural gas and oil) still maintain and even increase their share of associated mortalities. Specifically, while oil and coal increase their associated mortalities by 11.7% and 8.2% respectively, natural gas increases its by 62.5%. Overall, these three (oil, coal and gas) are projected under BAU to be responsible for 97.8% of mortalities.  Second, low-carbon technologies can cause deaths (represented by mortality factor in Table 1 of the paper) and are projected to cause even more deaths owing to their increasing share in the energy mix of case study regions.

Conclusion – positively looking ahead

As we conclude, we must highlight some startling truths. First, existing BAU scenarios are at the worst-case scenarios. This means that historical efforts at diversifying our energy mixes have only been helpful in preventing exacerbated issues of mortalities and emissions that would have exceeded worst-case scenarios. Second, we observe that low-carbon technologies generate deaths and emissions and at varying rates. This implies the need for pragmatism and optimal system design when diversifying energy mixes. Third, until there is a global strategy for sustainably energising the global south, savings made across the global north in avoidable deaths and emissions will continue to be eroded by the global south.


Agreements and words have little meaning if not backed with consistent actions. As the world attempts recovery on a global scale, it has become imperative to do so on the backbone of a green recovery mandate. This will involve bold decisions and ambitious targets to proposed emissions cuts. Furthermore, considering that it may be infeasible to exhaustively determine unintended consequences of such actions, just and equitable measures must be adopted to ensure countries in the global south can sustainably develop resilient energy systems that guarantee energy sufficiency.

Note on correction factor and procedure

Our computations all through the paper does not include any correction factor to compensate for variation in processes and any improvements among others that may limit GHG emissions. Values computed and used assume direct conversion. A correction factor will bring them in line with existing values and also help with averaging.

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Posted in All Posts, Just and Sustainable Transitions to Net Zero, The energy transition, Wellbeing and ecological economics

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The views and opinions expressed here are solely those of the individual authors and do not represent Sussex Energy Group.

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