Executive summary
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The 2020 report presents 43 indicators across five sections: climate change impacts, exposures, and vulnerabilities; adaptation, planning, and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement. This report represents the findings and consensus of the 35 leading academic institutions and UN agencies that make up The Lancet Countdown, and draws on the expertise of climate scientists, geographers, engineers, experts in energy, food, and transport, economists, social, and political scientists, data scientists, public health professionals, and doctors.
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5 years ago, countries committed to limit global warming to “well below 2°C” as part of the landmark Paris Agreement. 5 years on, global carbon dioxide (CO2) emissions continue to rise steadily, with no convincing or sustained abatement, resulting in a rise in the global average temperature of 1·2°C. Indeed, the five hottest years on record have occurred since 2015.
The changing climate has already produced considerable shifts in the underlying social and environmental determinants of health at the global level. Indicators in all domains of section 1 (climate change impacts, exposures, and vulnerabilities) are worsening. Concerning, and often accelerating, trends were seen for each of the human symptoms of climate change monitored, with the 2020 indicators presenting the most worrying outlook reported since The Lancet Countdown was first established.
These effects are often unequal, disproportionately impacting populations who have contributed the least to the problem. This fact reveals a deeper question of justice, whereby climate change interacts with existing social and economic inequalities and exacerbates longstanding trends within and between countries. An examination of the causes of climate change revealed similar issues, and many carbon-intensive practices and policies lead to poor air quality, poor food quality, and poor housing quality, which disproportionately harm the health of disadvantaged populations.
Vulnerable populations were exposed to an additional 475 million heatwave events globally in 2019, which was, in turn, reflected in excess morbidity and mortality (indicator 1.1.2). During the past 20 years, there has been a 53·7% increase in heat-related mortality in people older than 65 years, reaching a total of 296 000 deaths in 2018 (indicator 1.1.3). The high cost in terms of human lives and suffering is associated with effects on economic output, with 302 billion h of potential labour capacity lost in 2019 (indicator 1.1.4). India and Indonesia were among the worst affected countries, seeing losses of potential labour capacity equivalent to 4–6% of their annual gross domestic product (indicator 4.1.3). In Europe in 2018, the monetised cost of heat-related mortality was equivalent to 1·2% of regional gross national income, or the average income of 11 million European citizens (indicator 4.1.2).
Turning to extremes of weather, advancements in climate science allow for greater accuracy and certainty in attribution; studies from 2015 to 2020 have shown the fingerprints of climate change in 76 floods, droughts, storms, and temperature anomalies (indicator 1.2.3). Furthermore, there was an increase in the number of days people were exposed to a very high or extremely high risk of wildfire between 2001–04 and 2016–19 in 114 countries (indicator 1.2.1). Correspondingly, 67% of global cities surveyed expected climate change to seriously compromise their public health assets and infrastructure (indicator 2.1.3).
The changing climate has downstream effects, impacting broader environmental systems, which in turn harm human health. Global food security is threatened by rising temperatures and increases in the frequency of extreme events; global yield potential for major crops declined by 1·8–5·6% between 1981 and 2019 (indicator 1.4.1). The climate suitability for infectious disease transmission has been growing rapidly since the 1950s, with a 15·0% increase for dengue caused by Aedes albopictus in 2018, and regional increases for malaria and Vibrio bacteria (indicator 1.3.1). Projecting forward, based on current populations, between 145 million people and 565 million people face potential inundation from rising sea levels (indicator 1.5).
Despite these clear and escalating signs, the global response to climate change has been muted and national efforts continue to fall short of the commitments made in the Paris Agreement. The carbon intensity of the global energy system has remained almost flat for 30 years, with global coal use increasing by 74% during this time (indicators 3.1.1 and 3.1.2). The reduction in global coal use that had been observed since 2013 has now reversed for the past 2 consecutive years: coal use rose by 1·7% from 2016 to 2018. The health burden is substantial—more than 1 million deaths occur every year as a result of air pollution from coal-fired power, and some 390 000 of these deaths were a result of particulate pollution in 2018 (indicator 3.3). The response in the food and agricultural sector has been similarly concerning. Emissions from livestock grew by 16% from 2000 to 2017, with 93% of emissions coming from ruminant animals (indicator 3.5.1). Likewise, increasingly unhealthy diets are becoming more common worldwide, with excess red meat consumption contributing to some 990 000 deaths in 2017 (indicator 3.5.2). 5 years on from when countries reached an agreement in Paris, a concerning number of indicators are showing an early, but sustained, reversal of previously positive trends identified in past reports (indicators 1.3.2, 3.1.2, and 4.2.3).
Despite little economy-wide improvement, relative gains have been made in several key sectors: from 2010 to 2017, the average annual growth rate in renewable energy capacity was 21%, and low-carbon electricity was responsible for 28% of capacity in China in 2017 (indicator 3.1.3). However, the indicators presented in the 2020 report of The Lancet Countdown suggest that some of the most considerable progress was seen in the growing momentum of the health profession's engagement with climate change globally. Doctors, nurses, and the broader profession have a central role in health system adaptation and mitigation, in understanding and maximising the health benefits of any intervention, and in communicating the need for an accelerated response.
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Individual health professionals and their associations are also responding well, with health institutions committing to divest more than $42 billion worth of assets from fossil fuels (indicator 4.2.4)....
It is clear that human and environmental systems are inextricably linked, and that any response to climate change must harness, rather than damage, these connections.10 Indeed, a response commensurate to the size of the challenge, which prioritises strengthening health-care systems, invests in local communities, and ensures clean air, safe drinking water, and nourishing food, will provide the foundations for future generations to not only survive, but to thrive.11 Evidence suggests that being more ambitious than current climate policies by limiting warming to 1·5°C by 2100 would generate a net global benefit of US$264–610 trillion.12 The economic case of expanding ambition is further strengthened when the benefits of a healthier workforce and reduced health-care costs are considered.
