Most of today’s children could endure historic heatwaves as planet warms

New modeling shows that without urgent emissions cuts, most children born today will live through climate extremes far beyond anything seen in human history, with the poorest hit hardest.

Study: Global emergence of unprecedented lifetime exposure to climate extremes. Image Credit: Piyaset / Shutterstock

In a recent article published in the journal Nature, researchers investigated how global warming is affecting people exposed to unprecedented numbers of extreme climate events such as floods, crop failures, and heatwaves in their lifetimes.

Using demographic data and climate models, they found that if average global temperatures increase by 3.5°C, 92% of those born in 2020 could experience unprecedented heatwave exposure, while 14% may experience river flooding and 29% to crop failures.

Incorporating indicators of socioeconomic vulnerability into their analyses showed that more vulnerable populations will disproportionately bear this burden.

Background

As climate change worsens because of human activities, extreme weather events such as heatwaves, floods, and droughts are becoming more frequent, intense, and longer-lasting. These events pose serious risks to human societies, especially for younger generations who will live longer and thus face greater cumulative exposure.

Scientists have documented the increasing intensity and frequency of individual climate extremes. However, there has been limited understanding of how these compound exposures will accumulate over an individual’s lifetime, particularly in comparison to pre-industrial conditions.

Moreover, global climate policies currently place the Earth on a trajectory toward 2.7°C of warming by 2100, further heightening potential risks.

About the Study

This study aimed to quantify the numbers of people from different birth cohorts projected to experience unprecedented lifetime exposure (ULE) to six types of extreme climate events, and how these exposures vary across various levels of global warming and socioeconomic vulnerability.

Researchers combined outputs from multi-model ensembles of climate and impact simulations with global demographic datasets and socioeconomic indicators to assess future exposure to six climate extremes: heatwaves, crop failures, droughts, river floods, wildfires, and tropical cyclones (exposure defined by hurricane-force winds, excluding flood hazards).

They defined ULE as exposure levels that exceed the 99.99th percentile of what would be expected in a pre-industrial climate (i.e., virtually impossible without climate change).

Exposure was calculated at a 0.5°×0.5° grid-cell resolution, and each person’s cumulative exposure across their lifespan was estimated based on their birth cohort (1960 to 2020) and residence, assuming static demographics and no migration.

Researchers analyzed 21 global warming trajectories ranging from 1.5°C to 3.5°C by 2100. For each scenario, they identified the fraction of a birth cohort experiencing ULE per climate extreme and aggregated results globally and nationally.

The study also stratified exposure outcomes by socioeconomic vulnerability using the Global Gridded Relative Deprivation Index (GRDI) and average lifetime Gross Domestic Product (GDP) per capita.

This allowed a comparison of projected ULE between populations with high and low vulnerabilities. The modeling framework accounted for internal climate variability and regional differences in extreme event likelihood, helping to isolate the effect of global warming and socioeconomic conditions on cumulative exposure.

Findings

The study found that the fraction of people experiencing ULE to climate extremes increases dramatically across younger birth cohorts and higher global warming scenarios. In the case of heatwaves, ULE is projected for 52% of the 2020 birth cohort if global average temperatures increase by 1.5°C, but this rises to 92% under a 3.5°C scenario.

Even the 1960 cohort shows 16% exposure, but newer generations bear a much greater burden. At 3.5°C warming, 29% of those born in 2020 are expected to face ULE to crop failures, and 14% to river floods. Spatially, equatorial regions are hardest hit under lower warming, but the distribution becomes nearly global under higher warming.

The most socioeconomically deprived populations consistently face higher risks: under current policy trajectories, people in the most vulnerable 20% (as measured by GRDI or low GDP) are much more likely to experience ULE than their wealthier counterparts.

While heatwaves showed the highest exposure levels, other extremes like tropical cyclones, though geographically limited to regions prone to hurricane-force winds, still affected millions, particularly when analyses were restricted to at-risk regions.

Overall, the study underscores that continued global warming will expose large and growing fractions of the population to historically extreme conditions, with disproportionate impacts on the world’s most vulnerable. This highlights the moral and practical urgency of limiting warming and supporting adaptation strategies.

Conclusions

This study shows that many people, especially children, will face ULE to multiple climate extremes, like heatwaves, floods, droughts, and wildfires, under current warming trajectories.

However, the researchers warned that the findings likely underestimate total risk because they exclude non-local effects such as wildfire smoke crossing borders, adaptation responses, and within-country demographic differences. Vulnerabilities tied to age, gender, and disability are also not fully captured.

Despite uncertainties in modeling some extremes, especially hydrological ones, the grid-based approach (0.5° resolution) used helps estimate localized impacts more accurately.

The research team stressed that urgent action to limit global warming to 1.5°C—a target requiring immediate, deep emissions cuts—instead of 2.7°C could spare hundreds of millions of children from ULE, highlighting the critical importance of strong, sustained emissions reductions to protect future generations.