The BBC reports that sperm quality continues to drop. Specifically, researchers "found a 52.4% decline in sperm concentration, and a 59.3% decline in total sperm count in men from North America, Europe, Australia and New Zealand." While alarmist publications tout this as a 60% drop, the decline is accelerating and the researchers are concerned that inaction may lead to species extinction despite the effect not being observed in regions with high machismo, such as South America, Asia and Africa.
The study "aggregates 185 studies between 1973 and 2011, one of the largest ever undertaken." It supposedly overcomes selection bias occurring from patients attending fertility (virility?) clinics and selection bias of null results not being published in journals (churnals?). My intuition is that insights can be gained from studying transsexualism. Practitioners claim patients increase at the rate of 15% per year (doubling every five years), over many decades and with no end in sight. This is akin to Moore's law, Kryder's law, Butters' law, Hendy's law, Rider's law, Carlson's law or any other exponential halving or doubling. So, it doesn't take a genius to understand that it will become an increasingly widespread issue.
Regardless, masculine medical problems are vastly under-represented. By some estimates, spending on male medical problems is about 1/4 of spending on female medical problems. For example, when a man seeks help for a legitimate medical issue, such as declining testosterone, a patient at the lower end of the "normal" range may be denied treatment even if he is constantly exhausted.
Well, take care of yourself. Eat properly. Drink properly. Rest properly. Stay active. And if healthy food and exercise won't fix accumulated problems, consider hormone replacement. You may also want to watch two films which seem to be mentioned with increasing frequency and seem to predict our era with some accuracy: Children Of Men and Colossus: The Forbin Project. Children Of Men is the second bleakest film I've ever seen and the film I've seen most during its initial cinema release. It explores the scenario of global infertility leading to economic collapse. In addition to a nexus of cast and crew, the seamless plot and astounding compositing, the film is a fantastic example of mise-en-scène which is best explained by example.
Anyhow, enjoy the films and get your medical problems addressed.
Disclosure: People in my family are affected by virility and hormone problems. I have a professional interest in film, media encoding and art education.
So, say 4,999 / 5,000 men are sperm-count-deficient, but one, somewhere, somehow, retains his virility. To achieve replacement birth rates, women need to have 2.1 babies in their lifetime - so this one guy could "service" about 1500 women per decade, keeping them at or above replacement birth rates via whatever insemination methods are deemed socially acceptable. If he stays fertile for ~35 years and everybody signs on for the surrogate father thing, there's no decline in population whatsoever.
Stranger things have happened, though I think the article is puffing up the story just to sell some scare copies.
The big problem with that scenario would be the generations after that. If most of the humans in the world have the same fathers (or grandfathers, etc.) then genetic diversity would take a pretty big hit, and soon everyone would essentially be inbred. So we'd have another problem on our hands which might threaten our extinction after a few more generations.
Worked O.K. for Genghis Khan - not saying that inbreeding is good, or should go on indefinitely, but sooner or later we'll be editing our children's genes before they're conceived, right?