What happens to sex when the planet heats up?

The foundering polar bear swimming through slush is certainly a potent symbol, but when it comes to getting our attention there’s rarely something as provocative as sex.

All right, the sex we’re talking about isn’t of the human variety, but it’s still an essential touchstone in the discussion on climate change. And, as with polar bears, it starts in the cold.

Penguins, who also add the all-important “cute” factor to their environmental appeal, are apparently functioning as modern day miner’s canaries, signaling the beginning of major environmental shifts. In addition to the damage caused by pollution, over-fishing and developments that encroach on their breeding grounds, a variety of penguin species have been subject to the effects of a warming environment. In fact, according to Dee Boersma, a University of Washington biology professor and a penguin authority, these changes could lead to the birds’ extinction.

Among the direct effects of climate change on penguins’ breeding, the colony of penguins featured in the documentary March of the Penguins, lost its young when the ice they were nesting on broke apart, sending the underdeveloped chicks into the water. While the effect might not be the kind of tawdry detail we generally look for when it comes to sex, it does demonstrate how the whole purpose of the exercise can be undermined. No young, no point.

And aquatic birds aren’t the only species whose sexual activities are directly influenced by the Earth’s temperature. The sexual characteristics of tuatara lizards, a species more than 200 million years old, are defined by heat—the higher the temperature (above 21.5°C), the higher the probability of a male birth. With rising global temperatures, then, the tuatara is in danger of becoming extinct due to a lack of sexual diversity.

One of the solutions to increasing heat might be something as simple as a cloth draped over a nesting site, keeping the temperature relatively cool. Interestingly, placing a shading barrier over the tuatara’s breeding grounds has been suggested, albeit with more sophisticated (read: expensive) technology, for the entire planet.

After all, where troubled sexual reproduction is concerned, that’s an issue worth rallying a planet around.