Could climate change cause infertility?

University of Lincoln

The scientific community has long held an understanding about the effect of temperature on sperm production in mammals, but this new study sheds light on how spermatogenesis in insects is hampered at extreme temperatures.

In the new scientific paper, published in the Journal of Evolutionary Biology, and an academic letter recently published in Trends in Ecology & Evolution, University of Lincoln evolutionary ecologist Dr Graziella Iossa and behavioural ecologist Dr Paul Eady explain how the temperature at which an animal develops can impact its reproductive behaviour and physiology.

Dr Iossa said: “It is well known that the reason why testes are usually located outside the body cavity in male mammals is because sperm is damaged by excessive heat inside the body. However, it is now becoming clear that when subjected to heat stress, males become infertile before females do.

“It is not only intriguing that males and females show different sensitivity to temperature stress, it may also tell us something about how species will be affected by climate change and how we might buffer or tackle these sensitivities.”

Dr Iossa and Dr Eady, from the School of Life Sciences at Lincoln, have been leading research in this area for a number of years. Their most recent work, published in the Journal of Evolutionary Biology, examined sperm production and the copulatory behaviour of male and female Indian meal moths.

The Indian meal moth produces two types of sperm – a fertilizing eupyrene and a non-fertilizing apyrene sperm. The production of both sperm types is hampered by rising temperatures.

The moths were exposed to different temperatures (ranging from 20 – 33°C) during their development and up to the point when, as adults, they were ready to mate. The study found that sperm got shorter (and were therefore less effective) the higher the temperature the moths were exposed to, and that both males and females were less likely to engage in copulation when reared at the highest and lowest temperatures. Where they did copulate, the duration also decreased with increasing developmental temperature.

Studies looking at the impact of climate change on species have looked so far at the ability of species to survive under heat stress. Dr Iossa and Dr Eady are among the first scientists to examine how different temperatures impact on the reproductive behaviour of a species and thus fertility.

Previous work on other insects and also plants has found that you can mate females who have been heat stressed to non-stressed males, and they can produce offspring, however the reverse doesn’t work – heat-stressed males are often infertile. This shows that spermatogenesis (the production of sperm) appears more sensitive to heat stress than oogenesis (the production of eggs).

“These results are interesting because it is extremely important to understand how different species and different sexes will be affected by rising temperatures as the climate is changing,” explained Dr Iossa. “Models of the long-term impact of climate change on populations have focused on upper and lower critical thermal limits (CTLs), beyond which species survival is compromised. However research now suggests that species may become infertile – and therefore could become extinct – at a much lower temperature.

“Our study is consistent with current evidence that the production of sperm and mating behaviour are sensitive to developmental temperature and, in an era of global warming, further research in this area – examining both male and female fertility – is vital. The survival of natural populations ultimately depends on individuals being able to reproduce.”


Dr Iossa and Dr Eady’s paper, Temperature-induced developmental plasticity in Plodia interpunctella: reproductive behaviour and sperm length, is available to read in the Journal of Evolutionary Biology online. Dr Iossa’s letter on Sex-specific differences in Thermal Fertility Limits is published in Trends in Ecology & Evolution online.

From EurekAlert!

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April 16, 2019 7:07 am

suggestion for the insects… boxers, not briefs.

Reply to  Dave
April 16, 2019 7:15 am

“in an era of global warming, further research in this area – examining both male and female fertility – is vital.”… ding, ding ding!! show me the money!

Reply to  Dave
April 16, 2019 7:17 am


Reply to  Dave
April 16, 2019 10:54 am

Ohhhhh mammmmmmaaaaa … we need much$more$further$study … bend over taxpayers.

However, I have an easier solution! Import more 3rd world immigrants to America! Once here, they reproduce at a 3-1 rate compared to the native population!! Problem solved!! Or is a new problem created … .

Ron Long
Reply to  Dave
April 16, 2019 6:09 pm

Dave, I’m looking at the photo with this report and trying to figure out have this could produce a fertility event. Since I am only a simple country boy from Oregon I’m hoping you can explain the feet positions and how they could possibly relate to fertility? Thanks.

Curious George
April 16, 2019 7:16 am

Climate change can cause anything bad. It always has. Climate change caused alarmists. Isn’t infertility a step in the right direction?

Reply to  Curious George
April 16, 2019 8:19 am

Can we get a research grant for that?

Reply to  Tim.
April 16, 2019 12:45 pm

Ill be happy to conduct some … independent … uh, research … starting with the youngest most-fit PETA spokesmodels who stripped-off for their latest protest. Let’s see how THEIR reproductive systems are operating.

Bill Powers
Reply to  Curious George
April 16, 2019 11:07 am

Haven’t we (by that I mean some granted study somewhere) already discovered that Global warm…climate change causes planter warts and ingrown toenails? At that discovery anything goes. Why not infertility. Although I would first take a closer look at DDT.

Richard M
April 16, 2019 7:19 am

So, where do we sign up to be the human species lab rats?

Carbon Bigfoot
Reply to  Richard M
April 16, 2019 4:53 pm

Richard M:

According to the 1800 reports we’ve all been subjected to experimentation for a long time resulting in lower sperm counts, autism, brain tumors and DNA damage,,,,,,
Lets see if CAGW can compete with EMF and the frying of 5G.

April 16, 2019 7:20 am

So if overall human fertility did indeed get reduced by warming of the climate, both of which factors seem highly dubious .. then the alarmists should relax and declare victory. Human population plummets, returning the earth to a pristine pre-human condition and all the polar bears and butterflies and gray wolves and snail darters can rejoice and live in peace and happiness forever more.

Seriously – these fakers call themselves scientists? SMH

Thomas Homer
April 16, 2019 7:29 am

Humans are currently living in a variety of climates here on Earth. Can they show that human fertility rates actually do vary by climate?

Perhaps they could compare India/Pakistan with Mongolia.

Reply to  Thomas Homer
April 16, 2019 9:24 am

Good point.

Most of the places on the planet with very high human fertility are in the tropics and subtropics.

As if underpopulation is the world’s major problem today.

Kevin McNeill
Reply to  Thomas Homer
April 16, 2019 10:18 am

My thought exactly!

Ian Magness
April 16, 2019 7:38 am

The only fertility problem such “climate change” as has actually been happening could cause is being discussed by those wondrous XR (Extinction Rebellion) activists trying to bring London to a halt at the moment. The “problem”? Several have stated that “climate change” is so catastrophic for our futures that they can’t possibly consider bringing any children into this world.
This is a stance for which we, and our children, should all be eternally grateful – a kind of Darwin Award in advance – self-selecting their children out of the gene pool.

Reply to  Ian Magness
April 16, 2019 3:16 pm

Social Justice requires taxpayer funded sterilization clinics…in the name of reducing angst among propaganda consuming idiots. It’s only fair.

Who can be against justice?

Call them Darwinian Social Justice Clinics.

Future historians will write about how these clinics (inadvertently) produced a century of the greatest economic growth imaginable. After most parasitic humans died off via self sterilization, a critical mass of individual freedom resulted…resulting in an incredible $300 Trillion annual world domestic product during the so called Climate Optimum of the 22nd century.

kevin kilty
April 16, 2019 7:40 am

In my experience bugs come with warm weather.

lee Riffee
Reply to  kevin kilty
April 16, 2019 5:09 pm

Yes, and we all know there were few or no bugs around during the time of the dinosaurs…I guess all those that have been fossilized in amber must be very rare flukes.

Reply to  lee Riffee
April 16, 2019 10:43 pm

And of course, there were definitely no mammals around at the time of the dinosaurs.

Reasonable Sketic
April 16, 2019 7:41 am

This is great information to give to teens. Have sex during hot the summer afternoons and you don’t need condoms! Perhaps teens will advocate for more climate change after all! (Science said it, so it must be true)

Reply to  Reasonable Sketic
April 16, 2019 8:33 am

Hot Tubs as a form of Contraceptive?



Joshua Peterson
April 16, 2019 7:49 am

Let’s not look at genetic variability relevant to reproduction. Specifically, let’s avoid studying lineages with increased reproductive success at higher and lower temperatures, so as to avoid any implications about adaptation.

Joshua Peterson
Reply to  Joshua Peterson
April 16, 2019 8:09 am

Let us also avoid anything regarding survival rates at higher and lower temperatures; instead, by generalizing about reproductive rates in isolation, we can concoct all sorts of stories which support our narrative.

Bruce Cobb
April 16, 2019 7:52 am

Total pseudoscientific crap.

Al Miller
April 16, 2019 8:02 am

Thank goodness the climate has never changed until now! Otherwise we would never have survived! Sarc.

David Chappell
April 16, 2019 8:02 am

The experimental fallacy that immediately strikes me is that insects are not subject to a constant temperature during development (unlike mammals) but suffer the pangs and torments of diurnal variation which is probably greater than any rise in temperature due to climate change.

April 16, 2019 8:07 am

Of course it does. It causes everything bad. So now that that’s clear and the science is settled, we don’t need you anymore. The money spent for your research would be better spent on research for what you say is necessary – low carbon energy like gen 4 nuclear. Thanks for your hard work. Maybe your next gig can be at a modeling agency.

Andy Pattullo
April 16, 2019 8:37 am

And how do they feel about amorous activity after the frost comes, or is it politically incorrect to ask?

Tom in Florida
Reply to  Andy Pattullo
April 16, 2019 11:55 am

If the frost comes out, buy her a nice dinner first.

Carbon Bigfoot
Reply to  Andy Pattullo
April 16, 2019 5:43 pm

Andy P:
A woman I worked with in the 70s before PC and sexual innuendo was taboo had a saying at frost time……
WHEN THE FROST IS ON THE PUMPKIN—THAT’S THE TIME FOR DICKIE DUNKIN. She should know she had four kids……work at that time was a lot of fun.

April 16, 2019 9:05 am

Kerching !! Gotta get a slice of that CAGW research money!
When I was at university 50 years ago we learned about natural selection, adaptation and evolution. Have I missed something in the intervening years?

April 16, 2019 9:21 am

It is well known that each insect species has its own lower development threshold (LDT) and upper development threshold(UDT), which is the temperature range they can tolerate and function effectively. Both colder and hotter temperatures than the range are stressful. From

“A general response of insects to temperatures just below their LDT or above their UDT is the cessation of development and reproduction while the insects remain active and feed. The larvae may slowly grow and the adults accumulate reserves. These processes are terminated at more extreme temperatures.”

“During cooling, motility gradually decreases. At certain temperature, the neural and muscular activities are impaired and the insect lapses into cold stupor (chill coma). The stupor point is as high as 12°C in tropical insects including stored product pests, and in honey bees, around 5°C in many temperate species, near 0°C in most overwintering insects, and even below the freezing point in species living in very cold areas.”

“Gradual warming above UDT, which is for many species around 35°C but is never sharply delimited, increases the metabolic rate, loss of water, and motility. Around 40°C, the water loss increases sharply: the spiracles are wide open and the melting of cuticular lipids permits evaporation through the body surface. Exhaustion of water and nutrients leads to rapid decrease of motility and a drop of transpiration. At a certain temperature, heat stupor occurs. Survival at temperatures above the threshold is a function of temperature and length of exposure. Warming to the absolute upper lethal temperature, which is usually around 50-55°C, causes fast, irreversible tissue damage and death.”

My synopsis is

Carbon Based Lifeform
April 16, 2019 9:23 am

funny how all those species in the tropics seem to be able to ‘do it’ without a problem.

April 16, 2019 9:25 am

There is no doubt that “climate change” is causing infertility. Look at all the hand-wringing leftists who don’t want to bring children into the world. Darwinian self-selection: the best kind of infertility.

April 16, 2019 9:35 am

Since “Earth’s climate” is undeniably linked to latitude, wouldn’t infertility become more evident among populations closer to the equator. Seems like the premise of this hypothesis is questionable, to be very, very charitable.

April 16, 2019 9:35 am

“It is well known that the reason why testes are usually located outside the body cavity in male mammals is because sperm is damaged by excessive heat inside the body. ” I read the same thing about disposable diapers, but we keep using them on “kids” up to four or five years of age (potty training early is no longer done) and now on adults too. So……No big deal.

April 16, 2019 9:35 am

Two obvious problems with their “experiment”.
1) They exposed the animals to a temperature in one generation, that would take hundreds of generations in the real world.
2) Raise anything in an artificial environment, and you are going to see changes.

Reply to  MarkW
April 16, 2019 10:35 am

There are diverse precedents for characterization of processes in isolation, then extrapolating to absurd… universal proportions. Case in point, Catastrophic Anthropogenic Global Warming.

Reply to  n.n
April 16, 2019 10:36 am

extrapolating…. inferring to an absurd… universal frame of reference.

Walt D.
April 16, 2019 9:38 am

What a stupid question.
Climate Change can cause EVERTHING, or ANYTHING you want it to. /sarc

April 16, 2019 10:33 am

Yes, a climate of noise and other stressors, is a first-order forcing of physiological dysfunction in carbon-based men and women, and a probable forcing of infertility in a couple’s sexual consensus.

Joel Snider
April 16, 2019 10:43 am

‘Summer nights and my radio…’

In my humble observations, in warm weather, procreation is on the upswing.

Jerry Palmer
April 16, 2019 11:33 am

Better get Trump to build a northern border wall, Inuit immigration imminent!

Tom in Florida
April 16, 2019 11:53 am

Placing a man’s nuts in boiling water will keep a woman from becoming pregnant.

Hocus Locus
April 16, 2019 11:56 am

The “four footsie foreplay” stock photo used to illustrate this post begged me to add a fifth foot. So I found the high-res version and added the mithing fifth foot. It runs in the family. My father once filed an extra notch into a wooden cam inside his cuckoo clock so at midnight it struck thirteen.

April 16, 2019 12:50 pm

“Dr Iossa said: “It is well known that the reason why testes are usually located outside the body cavity in male mammals is because sperm is damaged by excessive heat inside the body.”

Which tropical country has experienced this condition, Dr Iossa?
Which warmer Optimum of the Holocene impaired human fecundity, Dr Iossa?
Why do you bother wearing insulating clothes, Dr Iossa?

Just more confirmation bias where the researcher find their own beliefs.

Rich Davis
April 16, 2019 1:16 pm

It’s got to be obvious by now that ctm posts EurekAlert! news releases as a form of ridicule.

Gunga Din
April 16, 2019 1:32 pm

Well, that explains why the reproduction rates are so low in nations and nature along the equator!
The Middle East has an area called “The Fertile Crescent”.
Now we have “The Infertile Circle”!

Dale S
April 16, 2019 2:00 pm

It would be nice if impact researchers remembered that AGW doesn’t actually cause “extreme temperatures”. That’s weather. AGW (all else being equal) just makes things slightly warmer than they would be over periods of time much longer than any insect’s lifespan.

Any biological creature incapable of surviving in the face of the tiny impact on actual temperatures from the gradual change in temperature anomaly would have gone extinct long ago from actual weather.

April 16, 2019 2:28 pm

This IS a bigger problem that needs to be addressed regarding infertility .
“There is increasing concern that the use of mobile phones may be associated with decreased semen quality and infertility. … Cell phone radiation may negatively affect sperm quality in men by decreasing the semen volume, sperm concentration, sperm count, motility, and viability, thus impairing male fertility”;year=2018;volume=5;issue=1;spage=1;epage=5;aulast=El-Hamd

“A team of researchers at the University of Newcastle (UON) have drawn a link between mobile phone radiation and a negative impact on sperm motility – the ability of sperm to swim – highlighting the potential danger of storing a mobile phone near male genitalia for prolonged periods.”

Gary Pearse
April 16, 2019 2:42 pm

Or, alternatively, we might just suddenly start reproducing like rabbits. That’s well within the usual brackets of climate change science. Odd this. I would have thought the totes would present this as a good news story.

lee Riffee
April 16, 2019 5:18 pm

I wonder how they think that insects survived during the age of the dinosaurs, or even the Carboniferous, when (thanks to excess O2 levels) they grew to enormous sizes. Seems to me that they’ve not taken account of the fact that (unless we are talking about bugs at latitudes where the sun does not set in summer time) night comes pretty much everywhere in the world and with it, falling temperatures. I can see where UHI might cause issues for some insects, but then again, there tends to not be as great a diversity of bugs in concrete jungles anyway.
There are precious few places on earth where average night time temps would fail to fall below 35c, even if the earth gets a couple of degrees warmer overall.

Flight Level
April 16, 2019 6:37 pm

Another take on the subject:

David Chappell
April 16, 2019 10:31 pm

BTW, which University of Lincoln?

Craig from Oz
April 17, 2019 12:08 am

I am surprised. I got to end of the comments without finding a single ‘Shrinkage’ comment.

Reply to  Craig from Oz
April 17, 2019 11:52 am

My nipples don’t shrink in cold. But yeah, men in Africa usually don’t have any shrinkage feature, so warming apparently deals with it. I’m confessing if I shaved better, I’d pass well for a lady in cold water. Won’t post the pics though.

April 17, 2019 6:17 am

It seems strange that the countries with the highest human fertility rate all seem to be quite warm.

Mark - Helsinki
April 17, 2019 8:05 am

must be why there are few kids in central Africa and the Middle east, India, Pakistan, ect.. oh wait

More junk science

Reply to  Mark - Helsinki
April 17, 2019 11:47 am

Not only that and the amount of Icelanders, but EurekAlert did a good job with Betteridge’s law.

The answer to the headline’s question is ‘No.’

Reply to  Hugs
April 17, 2019 4:25 pm

Good call.

Johann Wundersamer
April 20, 2019 4:43 am

We hope that the good Dr. didn’t use his own sperm to this comparative study – to women who were looking for help in his clinic:

Following his skiing holidays, following
his return from Caribbean holidays.

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