How climate change causes infertility

*Heatwaves caused by global warming induce long-lasting damage to sperm
*Diesel fumes are stunting children’s lungs, leaving them damaged for life
Climate change could pose a major threat to male fertility scientists have warned, as heatwaves cause serious and long-lasting damage to sperm.A study exposed beetles to artificial heatwaves and discovered increased temperatures are responsible for significant drops in male fertility. A five-day heatwave slashed sperm production in half and a second bout of prolonged warmth sterilised the animals.

The heat directly impacted sperm production but female fertility remains unaffected by the temperature fluctuation. Scientists claim this could explain how climate change impacts animal populations and help us understand the role it plays in the extinction of some species.

Researchers exposed red flour beetles to five-day heatwaves, with temperatures 5°C to 7°C (9°F to 12.6°F) higher than normal.Professor Matt Gage, a zoologist from the University of East Anglia who led the study, said: “We know that biodiversity is suffering under climate change, but the specific causes and sensitivities are hard to pin down.

“We’ve shown in this work that sperm function is an especially sensitive trait when the environment heats up, and in a model system representing a huge amount of global biodiversity.“Since sperm function is essential for reproduction and population viability, these findings could provide one explanation for why biodiversity is suffering under climate change.“A warmer atmosphere will be more volatile and hazardous, with extreme events like heatwaves becoming increasingly frequent, intense and widespread.

“Heatwaves are particularly damaging extreme weather events. Local extinctions are known to occur when temperature changes become too intense. We wanted to know why this happens. And one answer could be related to sperm.”

The findings, published in the journal Nature Communications, also revealed that offspring sired during heatwaves were less fertile and have lives a couple of months shorter than normal. Kirs Sales, a postgraduate researcher involved in the research, added: “Our research shows that heatwaves halve male reproductive fitness, and it was surprising how consistent the effect was.”

The study also found heatwaves has a dramatic impact on sexual behaviour as males mate only half as frequently as their counterparts in cooler environments.Sales added: “Insects in nature are likely to experience multiple heatwaves, which could become a problem for population productivity if male reproduction cannot adapt or recover.

“Two concerning results were the impact of successive heatwaves on males, and the impacts of heatwaves on future generations.“When males were exposed to two heatwave events 10 days apart, their offspring production was less than 1 per cent of the control group. “Insects in nature are likely to experience multiple heatwave events, which could become a problem for population productivity if male reproduction cannot adapt or recover.”

Meanwhile, a study has found that diesel fumes in London are so bad that children’s lungs are becoming stunted as a result.Tests on more than 2,000 eight- and nine-year-olds showed they had an average five per cent lower lung capacity than expected.This could put them at risk of lifelong breathing disorders, such as asthma and recurring chest infections, the researchers said.

Their study also showed London’s low emission zone – which since 2008 has meant lorries have had to pay a charge to enter the capital – has done little to improve children’s health.The researchers, whose work was published last night in the Lancet Public Health journal, blamed the nitrogen oxides and sooty particles in diesel fumes.

Professor Chris Griffiths, of Queen Mary University of London, said: “Despite air quality improvements in London, this study shows that diesel-dominated air pollution in cities is damaging lung development in children, putting them at risk of lung disease in adult life and early death. “We are raising a generation of children reaching adulthood with stunted lung capacity.

“This reflects a car industry that has deceived the consumer and central government which continues to fail to act decisively to ensure towns and cities cut traffic.”Medical experts are increasingly alarmed of the impact of traffic fumes on human health, including the risk of asthma, heart disease and cognitive development.

More than 40,000 people are thought to die early every year in the United Kingdom (UK) because of air pollution. The figure worldwide is around the nine million mark.Earlier this year, scientists revealed they had found tiny particles of vehicle soot in the womb of pregnant women, suggesting even unborn babies are at risk.

But the new research provides solid evidence that fumes are having a physical impact on children’s health at a very early age.The scientists tracked 2,164 children from 28 primary schools in the London boroughs of Tower Hamlets, Hackney, Greenwich and the City of London.The research team monitored children’s health and exposure to air pollutants over five years.

They found that after the low emission zone was introduced there were small improvements in levels of nitrogen oxides but no improvements in sooty particles.And despite these minor improvements in air quality, there was no evidence of a reduction in the proportion of children with small lungs or asthma symptoms.