Climate change may take six months off the average human lifespan, according to a study which found that women and individuals in developing nations are disproportionately affected.
The study, published recently in the journal PLOS Climate, evaluated average temperature, rainfall, and life expectancy data from 191 countries from 1940-2020.
In addition to measuring the isolated impacts of temperature and rainfall, the researchers designed a first-of-its-kind composite climate change index, which combines the two variables to gauge the overarching severity of climate change.
Results indicate that in isolation, a global temperature increase of 1 degree Celsius is associated with an average human life expectancy decrease of approximately 0.44 years, or about six months and one week.
A 10-point increase in the composite climate change index - which accounts for both temperature and rainfall - is expected to decrease the average life expectancy by six months, the researchers said.
Women and individuals in developing nations are disproportionately affected, they said.
"The global threat posed by climate change to the well-being of billions underscores the urgent need to address it as a public health crisis, as revealed by this study," said Amit Roy from Shahjalal University of Science and Technology in Bangladesh and The New School for Social Research, U.S.
The study emphasises that "mitigation efforts to reduce greenhouse gas emissions and proactive initiatives are essential to safeguard life expectancy and protect the health of populations worldwide," Roy added.
Temperature and rainfall - two telltale signals of climate change - cause myriad public health concerns, from the acute and direct (e.g., natural disasters like flooding and heat waves) to the indirect yet equally devastating (e.g., respiratory and mental illnesses), the researchers said.
While impacts like these are observable and well documented, existing research has not established a direct link between climate change and life expectancy, they said.
The team is hopeful that the composite climate change index will standardise the global conversation about climate change, become a usable metric for the nonscientific public and encourage collaboration and even friendly competition among countries to combat the impacts of climate change.
Mitigating greenhouse gas emissions and adapting to a changing environment are of particular importance, the researchers said.
To complement this large-scale approach, they suggest localised future studies that consider specific severe weather events (e.g., wildfires, tsunamis, and floods), the impacts of which cannot be fully captured through analysing temperature and rainfall alone.
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