C. Heuzé, S. Purkey, and G.C. Johnson (2022) It’s high time we monitor the deep ocean. Environmental Research Letters, vol 17, pp 121002. doi:10.1088/1748-9326/aca622

Earth is 71% ocean, 79% of which is deeper than 2000 m. Why 2000 m? That’s the current depth limit of our most advanced autonomous oceanographic instruments.

Put more bluntly: the largest component of the climate system is hardly observed. We counted; 200 000 profiles going deeper then 2000 m vs 6.5 million in the upper 500 m (that’s 3% if you prefer it this way). I knew it was bad, but even I am shocked.

See for yourself on the map below: Anywhere where you can see some blue in the background, we have 0 hydrographic profile there.

So unsurprisingly, models are bad at representing the deep ocean, but even if we had plenty of observations, they would still struggle as most of their geometry and settings are designed for the rest of the world.

Why should you care? Because there is A LOT of water down there, and it is warming. And when water warms, it expands, and that is very bad news for people like me who live by the coast.

We finish on some comparatively good news: The technology to observe the deep ocean is ready, and modellers can investigate alternative designs. All everyone need to start monitoring the deep ocean is money (easy, right?).

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