Growing economies across the world have seen the average life expectancy at birth rising since 1970, but at a significant cost to the environment, reports research published this week in Nature Climate Change.

Past research has confirmed that economic development improves the quality of life. However, as economies rely mainly on fossil fuels, improved life conditions lead to rising carbon emissions. Many studies have looked at the association between development and emissions but very few have analysed the dynamic relationship between development, human well-being and emissions, over time and across different world regions.

Andrew Jorgenson calculates the carbon intensity of human well-being (CIWB) - the ratio between per capita anthropogenic carbon dioxide emissions (in his study, derived from fossil fuel combustion and cement manufacturing) and average life expectancy at birth - for 106 countries over the period 1970-2009. He groups the countries in regional samples and estimates how the effect of economic development (measured by gross domestic product per capita) on CIWB has changed over the period in each group. He finds that, early in the period of study, increased development led to a reduction in CIWB for nations in Africa, but in recent decades the relationship has become less sustainable. For nations in Asia and South and Central America, development raises CIWB, and increasingly so over the period of study. The effect of development on CIWB for nations in the combined regions of North America, Europe and Oceania has been positive, larger than in other regions, and stable over time. The author concludes that as long as societies rely on fossil fuels, achieving better life conditions will drive up carbon emissions worldwide.