Climate and Extinction: Compounding Effects on Fertility

It’s not simply a matter of sea levels rising, or atmospheres warming, or food supplies dwindling. A recent scholarly article claims that the effects of climate change on sperm could prove critical to species extinction.

Writing in The Conversation, Ph.D. candidate Kris Sales starts out by noting that, dating back to the 1980s, intense and frequently occurring heatwaves have caused more deaths than any other weather phenomenon.

A 2003 survey published in the journal Nature determined that 8 in 10 relevant studies found fingerprints of global warming on wild animals and plants – a not-so-insignificant finding, when one considers that humans, like all other animals, are part of the food chain and stand to be impacted when other species suffer as a result of perennially hotter temperatures.

In fact, a more recent overview of more than 100 studies, entitled Accelerating extinction risk from climate change, concluded that anywhere from eight to 50 per cent of species such as trees, mollusks, and grasses would be impacted. It’s true: We really are interconnected with the rest of nature, with our survival depending very much on the well-being of plants and animals.

In regards to climate change and the effects on sperm, which up until now in animals has been mostly limited to the study of fruit flies, there aren’t many articles talking about it.

Which brings us to the subject of work led by Sales: Studying the effects of climate change on a model insect, in this case the red flour beetle.

Published in 2018 in the journal Nature Communications, the study by Sales and his team indicated that successive heatwaves could compound the devastation of earlier ones – with damage to male fertility extending to successive generations, potentially resulting in an intensifying vortex of population declines. The team’s hope, as articulated by Sales in The Conversation: That “this new knowledge can help predict which species are most likely to be vulnerable, allowing conservationists to prepare for the trouble ahead”.

But how does climate change look to impact human fertility?

A 2015 article published by the World Economic Forum starts out by noting that global warming could affect fertility in a couple of ways: By influencing sexual behavior itself, which becomes more strenuous at higher temperatures, and by adversely impacting reproductive health factors such as menstruation and sperm motility (swimming ability).

The article went on to cite a global circulation model predicting the number of hot days per year (where the temperature exceeds 80F) as increasing from 30 at present to 90 by the end of the 21st century, resulting in an estimated reduction of births of 107,000 per year. More summer births will also occur, which could wind up threatening infant health.

Unfortunately, climate change itself isn’t the only culprit in threatening fertility. A range of environmental factors come into play.

A 2005 study published in the journal Human Reproduction Update provides an overview of environmental and occupational factors affecting fertility and IVF success.

Impact abounds over several different areas, including occupational exposures such as psychological stress and chemical agents. Other factors that come into play involve alcohol use, diet and obesity, and smoking. There’s also the whole question of evaluating one’s inadvertent exposure to environmental pollutants, such as those emitted by factories and combustion-engine vehicles.

A guide published by the U.S. Department of Health and Human Services cited a governmental study that found that specific versions of organochlorine pesticides as well as polychlorinated biphenyls (PCBs) were connected to “increased time-to-pregnancy or decreased couple fecundity”.

And in case anyone believes that the science on all of this is mostly new, it’s worth remembering that the known impacts of climate change on fertility have been posited since at least 2003, when a study published in the journal Medical Hypotheses declared that “[a]n inverse relationship was found between changes in global temperatures and birth rates” in every one of 19 covered countries. And that the results of the researchers’ analyses “were consistent with the underlying premise that temperature change affects fertility”.

With compelling cases to be made for the impact of climate change on other species as well as on humans, discretion and caution in protecting one’s fertility should prove far more beneficial than holding out for definitive proof, which might not occur until the findings emerge too late for proactive measures.

Protecting your assets today provides the best possible defense.