The rise of primary energy use and CO2 emissions over four decades across 70 countries is not closely correlated with increases in life expectancy, a new study finds.

This suggests that increased fossil fuel use is not a key determinant of increased life expectancy, the lead author tells Carbon Brief.

The analysis finds that increased access to electricity in the home was much more closely associated with a longer life expectancy over the 40-year study period.

However, increases in access to home electricity were not highly correlated with increases in CO2 emissions, the study notes – suggesting that fossil fuels are not fundamental to access.

It is important to note, however, that there are limitations to using coarse indicators, such as primary energy use and life expectancy, to infer relationships between fossil fuel use and health and wellbeing, another scientist tells Carbon Brief.

Fossil fix?

Tackling climate change requires countries to rapidly transition away from burning fossil fuels.

In response to calls for action, some commentators have argued that using more fossil fuels can bring about increases in the health and wellbeing of populations – and that, because of this, developing nations should not be discouraged from using them.

The new study, published in Environmental Research Letters, addresses this claim.

It finds that, over time, there is no strong association between increased life expectancy and fossil fuel use, explains lead author Prof Julia Steinberger, an ecology economist from the University of Leeds. She tells Carbon Brief:

"I was really, really shocked to see how little the increases in CO2 emissions and primary energy [use] could account for increases in life expectancy. I thought, by fluke, they would account for more because they've been growing tremendously all over the world."

Patterns of change

For her analysis, Steinberger and colleagues looked at changes in several key per-capita metrics from 1971-2014 across 70 countries. (The authors chose to use every country which offered all the data required for the analysis. Together these countries represent 80% of the global population.)

The chart below shows the changes in these metrics, which include food supply (silver), life expectancy (gold), CO2 emissions (yellow), primary energy use (light green), population growth (pink), residential electricity (dark green) and income by market exchange rate (blue) and "purchasing power parity" – a domestic purchasing metric that also considers the relative cost of living and inflation rates in different countries (orange). ("Primary energy" is a measure of all the energy present at the point of extraction for fossil fuels or generation for renewables.)

Relative changes to key social indicators across 70 countries from 1971-2014. Indicators include food supply (silver), life expectancy (gold), CO2 emissions (yellow), primary energy use (light green), population growth (pink), residential electricity (dark green) and income by market exchange rate (blue) and "purchasing power parity" (orange). Source: Steinberger et al. (2020)

The chart shows how residential electricity and purchasing power parity have increased the most rapidly out of all the indicators.

The researchers used a new analysis method, called "functional dynamic composition", which involves using a set of equations to examine to what degree changes in one metric were linked to changes in another. This means the authors were able to measure correlations between different metrics, but they were not able to detect causal links.

For example, they looked at how closely increases in per-capita CO2 emissions were linked to increases in life expectancy. "We use CO2 emissions as an indicator, but really they are a proxy for fossil fuel use," says Steinberger.

They find that increases in per-capita CO2 emissions and primary energy use were both linked to around a quarter of the increase in life expectancy. (Over the study period, average life expectancy increased by 14 years across the studied countries.)

By contrast, increases in residential electricity were tied to more than half of the increase in life expectancy, the study finds. Steinberger explains:

"It might be that residential electricity is a good proxy for other things that matter and in itself doesn't matter very much. But I can think of very good reasons why residential electricity matters a lot in allowing people to live healthy decent lives."

For example, having access to electricity in the home allows people to refrigerate food, stay in contact using the internet and forgo the use of wood and charcoal-burning stoves, which can negatively affect health, she adds.

The authors also studied the links between increases in residential electricity access and increases in CO2 emissions.

They find that increases in CO2 emissions were only linked to 36% of the increases in residential energy, suggesting fossil fuels are not key for the provision of home electricity.

Instead, it is likely other factors not studied, such as policies for improving grid access, could account for increases in home electricity access, Steinberger says.

Increases in purchasing power parity were also highly correlated with increases in life expectancy – though not as highly correlated as increases in residential electricity, the study finds.

The authors also found an association between increases in primary energy consumption and increases in per-capita income by market exchange rate.

Accessing change

The findings suggest that it is improving access to electricity, rather than continued fossil fuel use and primary energy growth, that is most important for human health and wellbeing, Steinberger says:

"I think that the main message for policymakers is that the social wellbeing of the population does not depend on fossil fuel use and certainly not on its growth. And, in fact, not on energy growth. There's no evidence that the sheer quantity of energy we use correlates with wellbeing over time."

However, it is worth noting that it should not be expected that primary energy use would be highly correlated with health and wellbeing, says Dr Brenda Boardman, an emeritus fellow and researcher of low-carbon energies at the Environmental Change Institute at the University of Oxford, who was not involved in the study. She tells Carbon Brief:

"Primary energy is effectively what comes out of the ground [as well as what] is generated by renewables. [Then there's] delivered energy, which is what we purchase, at the meter. With gas, this is virtually the same as primary energy, but with electricity is it only about a third of primary energy. This is because the average fossil-fuelled power station is only around 35% efficient, perhaps a bit more efficient for a modern plant. This means almost two-thirds of the primary energy is wasted."

In addition, life expectancy is not a perfect indicator for human health and wellbeing, she adds. "With life expectancy, the deep culture and infrastructure of the country is paramount."

Steinberger, J. K. et al. (2020) Your money or your life? The carbon-development paradox, Environmental Research Letters, doi:10.1088/1748-9326/ab7461