Women in rural areas suffer substantially greater economic losses from the impacts of climate breakdown than men in developing countries, research has shown, and the gap is likely to widen further.

Households headed by women in rural areas lost about 8% more of their income to heat stress than male-headed households, and their reduction in income when floods struck was about 3% greater than the loss to men, according to data released by the UN’s Food and Agriculture Organization (FAO) on Tuesday.

The difference, taken across the world’s low- and middle-income countries, adds up to about an extra $37bn lost to women from heat stress and $16bn extra from floods each year.

The researchers estimate a 1C increase in long-term average temperatures is associated with a reduction of about a third in the incomes of female-headed households, compared with those of male-headed households.

Children and women also tend to have to work more when extreme high temperatures strike, with children working nearly an hour extra a week in rural areas on average, according to the report.

Lauren Phillips, the deputy director of inclusive rural transformation and gender equality at the FAO and a co-author of the report, said governments were failing to take into account the factors that disadvantage women, and climate aid was not targeted in ways that would address the gender gap. She said the report was the first to quantify this clearly.

“This gender gap can have a very dramatic impact on GDP growth,” she told the Guardian. “We could increase GDP by 1% globally if we could reduce food insecurity for 45 million people, by focusing on women.”

Less than 2% of climate finance globally is estimated to reach small-scale food producers. Women are hit harder than men by the climate crisis in part because the impacts exacerbate existing inequalities, such as unequal rights to land tenure and a lack of economic opportunities for women. Women also tend to bear more of the burden of providing water, fuel and food. Governments and donors could address these problems with better targeting of assistance, Phillips said.

“Targeting women in ways that ensure their empowerment has greater benefits,” she said. “There are multiple gains and benefits from targeting climate finance at women. We need to intentionally focus on this, to get much higher returns on investment.”

The researchers analysed socioeconomic data from more than 100,000 rural households, representing more than 950 million people, across 24 low- and middle-income countries. They cross-referenced this with 70 years of daily precipitation and temperature data to build a detailed picture of how changes to the climate and extreme weather affected people’s incomes, labour and lives.

It adds to a growing body of research that shows women and vulnerable people suffer disproportionately from the impacts of the climate crisis. The report also found that older people tended to be more affected than the young, who may have more opportunities to move to escape the impacts of extreme weather, and the already poor were more vulnerable than those on higher incomes.

Maximo Torero Cullen, the chief economist at the FAO, wrote in the foreword to the report: “Climate change is widening even further existing income gaps in rural areas, pushing vulnerable people towards maladaptive coping strategies and ultimately making it harder for these groups to escape cycles of poverty and hunger.”

Poorer households were hit by losses about 5% greater on average than their better-off neighbours when flooding or extreme temperatures struck, the report found.

Phillips said: “What we found was that climate change was making the rural poor more dependent on agriculture. Agriculture will become more difficult as the climate changes further.”