from the world's big
Heatwaves significantly impact male fertility, says huge study
As the world gets hotter, men may have fewer and fewer viable sperm
- New research on beetles shows that successive exposure to heatwaves reduces male fertility, sometimes to the point of sterility.
- The research has implications both for how the insect population will sustain itself as well as how human fertility may work on an increasingly hotter Earth.
- With this and other evidence, it is becoming clear that more common and more extreme heatwaves may be the most dangerous aspect of climate change.
When we hear that climate change causes "extreme weather events," our minds jump to hurricanes ripping palm trees out of the ground or snowstorms burying cars. But one of the most dangerous kind of extreme weather event is much less visible than, say, a tornado tearing the roof of a house. Heatwaves kill more people than all other weather events combined, and they're on the rise.
During the summer of 2003, an estimated 70,000 Europeans died when a deadly heatwave swept through the region. As the globe continues to warm, 150 Americans are projected to die every summer day by the mid-2040s. Aside from directly causing death from heatstroke, dehydration, other heat-related conditions, high heat also weakens cognition. Violent crimes, too, tend to spike on hotter-than-average days.
Now, a new study has uncovered another threat posed by heatwaves. It turns out the prolonged exposure to high heat reduces male fertility, and repeated exposure to successive heatwaves can even cause sterility.
Studying reproductive performance under heatwave conditions
This image shows the temperature anomalies across Europe during the devastating 2006 heatwave.
The study, recently published in Nature, examined the sperm viability of red flour beetles under heatwave conditions. In a corresponding blog post, study co-author Matthew Gage wrote, "a wealth of research since the start of last century, mainly on warm-blooded mammals (including humans), has shown that environmental or experimental warming by even a few degrees can cause declines in sperm quality and male ability to fertilise."
He points out that most of these studies have been conducted on endothermic, or warm-blooded, animals, but very few studies have been conducted on exothermic, or cold-blooded, animals like insects. Given that the vast majority of animals are ectothermic and that insects serve as food or pollinators for many animals and plants, understanding how climate change affects these creatures is critical to preserving our ecosystem. What's more, studying sperm viability in insects serves as a model for how heatwaves will affect other animals—like humans.
What did they find?
The researchers exposed red flour beetles (like this one) to high-heat conditions to observe their reproductive performance. (Wikimedia Commons)
The researchers exposed their beetles to heatwave-like conditions over the course of five days. Male red flour beetles like temperatures at about 35 degrees Celsius, or 95 degrees Fahrenheit. The experiment exposed them to an environment that was 42 degrees Celsius, or 107.5 degrees Fahrenheit. Depending on where you live, that may sound like an unlikely temperature, but the authors noted that over 90 countries experience heatwaves in that temperature range or higher.
After their extended sauna session, the beetles were given the chance to mate with a female of the species. Compared to male beetles in the control group, the heat-exposed beetles didn't do so well. They produced 75% less sperm, and only one third of their sperm was viable. Overall, the heat-exposed beetles' reproductive performance was cut in half.
But nature is adaptable, right? One might expect the beetles to eventually get over the initial shock of their new, hot environment and perform better. This research showed that, if anything, the opposite is true, at least in the short term. A second exposure to heatwave conditions made the beetles almost completely sterile.
It gets worse; not only did the heat-exposed male beetles do worse than their cooler peers, their male offspring were also less fertile than the offspring of the control beetles. Even when this new generation of beetles was not exposed to heatwave conditions, they had a 25% reduction in mating success. What's more, they lived significantly shorter lives than the control beetles, too.
We've known for a while that certain environmental conditions can affect the health and fertility of offspring, but usually this is in response to irradiation, exposure to toxic chemicals, or stress. When an animal is exposed to an unhealthy environment, the genetic material contained in their sperm becomes damaged, hamstringing the next generation's ability to reproduce. This research suggests that exposure to high heat damages offspring's reproductive ability in the same way.
The environmental impact
While this study looked specifically at beetles, evidence suggests heatwaves will affect mammals in much the same way. Exposing mice to hotter temperatures reduced fertility by 75%, for instance. Overall, "this work reveals that sperm are very sensitive to heat," writes Gage. "Environmentally-relevant experimental heatwaves damage sperm function, leading to reduced fertility and a decline in offspring performance."
If this effect is widespread enough, it could throw a serious monkey wrench into the inner workings of our ecosystem. The importance of insects in the diets of large animals cannot be overstated. As the globe continues to warm, insect populations are crashing. One study in Germany found that the local insect population had dropped by 78% in just 24 years, which appears to be part of a global trend. While it can't be said that this is entirely due to increasingly common and extreme heatwaves, this research suggests that they may play a major role.
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Construction of the $500 billion dollar tech city-state of the future is moving ahead.
- The futuristic megacity Neom is being built in Saudi Arabia.
- The city will be fully automated, leading in health, education and quality of life.
- It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
The Red Sea area where Neom will be built:
Saudi Arabia Plans Futuristic City, "Neom" (Full Promotional Video)<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="c646d528d230c1bf66c75422bc4ccf6f"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/N53DzL3_BHA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Frequent shopping for single items adds to our carbon footprint.
- A new study shows e-commerce sites like Amazon leave larger greenhouse gas footprints than retail stores.
- Ordering online from retail stores has an even smaller footprint than going to the store yourself.
- Greening efforts by major e-commerce sites won't curb wasteful consumer habits. Consolidating online orders can make a difference.
A pile of recycled cardboard sits on the ground at Recology's Recycle Central on January 4, 2018 in San Francisco, California.
Photo by Justin Sullivan/Getty Images<p>A large part of the reason is speed. In a competitive market, pure players use the equation, <em>speed + convenience</em>, to drive adoption. This is especially relevant to the "last mile" GHG footprint: the distance between the distribution center and the consumer.</p><p>Interestingly, the smallest GHG footprint occurs when you order directly from a physical store—even smaller than going there yourself. Pure players, such as Amazon, are the greatest offenders. Variables like geographic location matter; the team looked at shopping in the UK, the US, China, and the Netherlands. </p><p>Sadegh Shahmohammadi, a PhD student at the Netherlands' Radboud University and corresponding author of the paper, <a href="https://www.cnn.com/2020/02/26/tech/greenhouse-gas-emissions-retail/index.html" target="_blank">says</a> the above "pattern holds true in countries where people mostly drive. It really depends on the country and consumer behavior there."</p><p>The researchers write that this year-and-a-half long study pushes back on previous research that claims online shopping to be better in terms of GHG footprints.</p><p style="margin-left: 20px;">"They have, however, compared the GHG emissions per shopping event and did not consider the link between the retail channels and the basket size, which leads to a different conclusion than that of the current study."</p><p>Online retail is where convenience trumps environment: people tend to order one item at a time when shopping on pure player sites, whereas they stock up on multiple items when visiting a store. Consumers will sometimes order a number of separate items over the course of a week rather than making one trip to purchase everything they need. </p><p>While greening efforts by online retailers are important, until a shift in consumer attitude changes, the current carbon footprint will be a hard obstacle to overcome. Amazon is trying to have it both ways—carbon-free and convenience addicted—and the math isn't adding up. If you need to order things, do it online, but try to consolidate your purchases as much as possible.</p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
Chronic irregular sleep in children was associated with psychotic experiences in adolescence, according to a recent study out of the University of Birmingham's School of Psychology.