The Lancet Countdown is an international collaboration (43 academic institutions and UN agencies) that independently monitors the health consequences of a changing climate.

The 44 indicators of this report expose an unabated rise in the health impacts of climate change and the current health consequences of the delayed and inconsistent response of countries around the globe—providing a clear imperative for accelerated action that puts the health of people and planet above all else.

Deepening inequities in a warming world

The concurrent and interconnecting risks posed by extreme weather events, infectious disease transmission, and food, water, and financial insecurity are over-burdening the most vulnerable populations. Through multiple simultaneous and interacting health risks, climate change is threatening to reverse years of progress in public health and sustainable development.

Record temperatures in 2020 resulted in a new high of 3·1 billion more person-days of heatwave exposure among people older than 65 years and 626 million more person-days affecting children younger than 1 year, compared with the annual average for the 1986–2005 baseline.

Furthermore, populations in countries with low and medium levels of UN-defined human development index (HDI) have had the biggest increase in heat vulnerability during the past 30 years, with risks to their health further exacerbated by the low availability of cooling mechanisms and urban green space.

During any given month in 2020, up to 19% of the global land surface was affected by extreme drought; a value that had not exceeded 13% between 1950 and 1999.

In parallel with drought, warm temperatures are affecting the yield potential of the world’s major staple crops—a 6·0% reduction for maize; 3·0% for winter wheat; 5·4% for soybean; and 1·8% for rice in 2020, relative to 1981–2010 (indicator 1.4.1) - exposing the rising risk of food insecurity.

The changing environmental conditions are also increasing the suitability for the transmission of many water-borne, air-borne, food-borne, and vector-borne pathogens, especially in the low HDI country group:

• The number of months with environmentally suitable conditions for the transmission of malaria rose by 39% from 1950–59 to 2010–19 in densely populated highland areas in the low HDI group;

• The epidemic potential for dengue virus, Zika virus, and chikungunya virus increases as well;

• Similar findings are observed in the environmental suitability for Vibrio cholerae, a pathogen estimated to cause almost 100000 deaths annually;

Even with overwhelming evidence on the health impacts of climate change, countries are not delivering an adaptation response proportionate to the rising risks their populations face. only 47 (52%) of 91 countries reported having a national adaptation plan for health, with insufficient human and financial resources identified as the main barrier for their implementation.

An inequitable response fails everyone

More than 60% of people in high-income countries have received at least one dose of a COVID-19 vaccine compared with just 3.5% of people in low-income countries. Data in this report exposes similar inequities in the global climate change mitigation response.

At the current pace of reduction, it would take more than 150 years for the energy system to fully decarbonise. The use of public funds to subsidise fossil fuels is partly responsible for the slow decarbonisation rate.   The world is not on track to realising the health gains of the transition to a low-carbon economy. Current global decarbonisation commitments are insufficient to meet Paris Agreement ambitions and would lead to a roughly 2·4°C average global temperature increase by the end of the century.

Moreover, the economic recovery from the pandemic is already predicted to lead to an unprecedented 5% increase in greenhouse gas emissions in 2021, which will bring global anthropogenic emissions back to their peak amounts. The current economic recession is threatening to undermine the target of mobilising US$100 billion per year from 2020 onwards to promote low-carbon shifts and adaptation responses in the most underserved countries, even though this quantity is minute compared with the trillions allocated to COVID-19 recovery.

An unprecedented opportunity to ensure a healthy future for all

By directing the trillions of dollars that will be committed to COVID-19 recovery towards the WHO’s prescriptions for a healthy, green recovery, the world could meet the Paris Agreement goals, protect the natural systems that support wellbeing, and minimise inequities through reduced health effects and maximised co-benefits of a universal low-carbon transition.

There is a glimpse of positive change through several promising trends in this year’s data:

• electricity generation from renewable wind and solar energy increased by an annual average of 17% between 2013 and 2018;

• investment in new coal capacity decreased by 10% in 2020; and

• the global number of electric vehicles reached 7·2 million in 2019.