El Niño Brings Venomous Sea Snakes To California


Robin Andrews

Science & Policy Writer

3056 El Niño Brings Venomous Sea Snakes To California
A yellow-bellied sea snake in Costa Rica. Aloaiza / Wikimedia Commons

Here’s something you’re unlikely to hear at the United Nation’s Climate Change Conference in Paris this November: If you do nothing about climate change, sea snakes will get you. To be fair, that’s a slightly exaggerated statement, but technically it’s not untrue – extremely venomous sea snakes thrive in warmer waters, and climate change is leading to increased global ocean temperatures. Presently, El Niño is providing an example of this: Due to warming marine waters off the coast of California, the Golden State is experiencing an invasion of these slithering aquatic beasties, as reported by CNN.

Yellow-bellied sea snakes (Pelamis platura) are fascinating little creatures: swimming vessels of venom, they often reside in the warmer regions of the Pacific and Indian Oceans, although they sometimes turn up in Alaska and New Zealand as well. If threatened, they inject a specific kind of venom that severely damages the nervous system of anything unfortunate enough to get in their way.


They require warm water to live in long term, and until now, the coast of California was not well known for hosting social gatherings of sea snakes, with the last sea snake washing up on the shore way back in 1972. El Niño, however, has changed all that, warming the waters enough to cause a huge influx of them.

El Niño – the “Christ child” – is the warm phase of something called the El Niño Southern Oscillation (ENSO), a complex pattern of sea surface temperature changes that interact to produce global climatic effects. Under normal conditions, warmer waters accumulate in the central southern Pacific Ocean, counterbalanced by the cold water along the South American coastline. If this warmer water shifts eastward and spreads out towards the continental coast, the cold coastal water that normally upwells from the depths disappears, and the temperature across the southern Pacific Ocean becomes less variable. The lack of any upwelling cold water increases the sea surface temperatures further, and it is this warming effect that is known as El Niño. It is somewhat predictable by climatologists and meteorologists, occurring once every two to seven years, lasting nine to 24 months.

As it turns out, these waters off the coast of California have been warmed enough for sea snakes to find it exceedingly comfortable to live in, at least for the time being. “Because the water is so warm here now, these snakes can swim, hunt and reproduce just like they could in the northern part of their tropical range," Dr. Paul Barber, professor of ecology and evolutionary biology at UCLA, told The Huffington Post. "Simply put, they are here because the warmer El Niño conditions have expanded the range of suitable environmental conditions for this snake. This has also happened with other marine species like hammerhead sharks.”

The El Niño event this year is “significant and strengthening,” according to a recent forecast by the National Oceanic and Atmospheric Administration (NOAA); it will last until spring of next year, so the sea snakes’ gap year to California will probably last until then. 


The official advice if you see a sea snake is, unsurprisingly, to not touch it.


  • tag
  • climate change,

  • el nino,

  • sea snakes,

  • venom,

  • California