When it comes to measuring the impact of the climate crisis, we tend to rely on two simple metrics: human deaths and economic losses. These data points are incredibly useful for understanding what we would be exposing ourselves to if we didn’t reduce emissions, but they only capture part of the suffering that extreme weather events and collapsing ecosystems will bring.

Take, for example, a recent study on temperature-related mortality. Bitter cold in Europe is typically more deadly than heat. Between 1991 and 2020, cold-related deaths were about eight times higher than heat-related deaths. Our warming planet is set to change that balance across the continent.

Heat-related deaths could triple from current levels by 2100 if temperatures rise by 3°C (5.4F) — consistent with current climate policies — to almost 129,000 a year from about 44,000 a year. But the deaths, which will overwhelmingly occur in people over 85, are only a small part of the health burden from extreme heat.

As Madeleine Thomson, head of climate impacts and adaptation at Wellcome, a global health research charity, said in response to the study: “Extreme heat kills, but it also causes serious damage to health.” These ailments will affect not only our older people, but also the youngest members of society and everyone else.

Research is increasingly highlighting the effects of excess heat on pregnant women, for example. Growing a new human is hard work, and a woman’s body goes through several physiological changes to accommodate this, including a 40% increase in the amount of blood pumped through the body. These changes put pregnant women at greater risk for heat exhaustion and heatstroke.

Not only are parents of children more vulnerable to heat, but exposure to high ambient temperatures is also associated with poorer health for both mother and child, including increased rates of miscarriage, stillbirth, preterm birth, congenital malformations, gestational diabetes, gestational hypertension and preeclampsia.

A study in India found that the risk of miscarriage doubled for women who were exposed to extreme heat at work. Women in developing countries are particularly vulnerable because they are more likely to do physical work outdoors and have less access to cooling than women in more developed countries.

But the consequences affect everyone. Studies in high-income countries have shown a roughly 15% increase in the risk of preterm birth and stillbirth during heatwaves. Jane Hirst, a senior obstetrician at the George Institute for Global Health who contributed to the India study, told the BBC that “the negative effects (on pregnancy) can be seen at much lower temperatures in more temperate climates, such as the UK.”

There may also be long-term effects on children. A 2024 systematic review of the limited existing research on health and socioeconomic consequences in later life found that increased heat exposure during pregnancy may be associated with poorer educational outcomes and an increased risk of heart disease and childhood asthma.

Researchers from the University of the Witwatersrand in South Africa also observed links with worsening mental health, including a higher risk of eating disorders and schizophrenia.

We’re also starting to better understand how periods of high temperatures negatively impact mental health in general. As my columnist colleague Lisa Jarvis has written, the heat not only makes us all feel exhausted and irritable, but it also exacerbates “common mood disorders like anxiety and depression, as well as rarer conditions like schizophrenia and self-harm.”

We’re likely to find more links between heat and health as global warming tightens its grip. A mysterious kidney failure epidemic in Sri Lanka is likely caused by extreme heat exposure, dehydration, and pesticide contamination of groundwater. Up to one in five residents of some high-density areas is affected by acute kidney injury or failure, and the condition often appears or progresses rapidly.

A similar epidemic was reported among migrant workers returning from the Persian Gulf, with young men leaving home healthy and returning with kidney failure after being exposed to brutal heat at work. Scientists began to document kidney disease in manual workers in other hot countries as well.

The health effects of extreme heat are already here and go far beyond tragic, preventable deaths. Yet there are huge knowledge gaps in understanding everything from the biological mechanisms behind heat-related harm to effective solutions.

Many scientists have cited the difficulty of obtaining funding for such research due to its interdisciplinary nature, while the Rockefeller Foundation, a philanthropic organization that funds medical research and the arts, notes that only 2% of adaptation funding and 0.5% of overall climate funding goes to improving health outcomes. This needs to change. After all, our health is our wealth, and climate change is already depleting it.

2024 Bloomberg LP Distributed by Tribune Content Agency, LLC.