New research suggests water worlds, giant worlds wrapped in a global ocean with little to no land at all, may actually be habitable over a very long time. Longer than even Earth-like worlds may be. This is something of a surprise: Sky Father might have slipped us another finger to pull.
One of the concerns, traditionally, about worlds with a global ocean being habitable, has been that the climate may not be stable. The climate may go through wild extremes, which is something life shouldn't have, as far as we understand, to develop. On Earth, the shallow oceans work in a cycle with volcanoes to cycle carbon dioxide through at a relatively stable rate (from a geological time scale point of view). Plankton builds shells using carbon dioxide, producing carbonate, this gets deposited at the bottom of the ocean and as the crust of the ocean is subducted under a continent, the carbonates melt, break down and carbon dioxide is vented out a volcano. Over time and as the sun gets hotter, the amount of carbon dioxide in the atmosphere decreases, preventing a terrestrial world from overheating as well. A relatively shallow ocean and continents were thought to be key.
On a water world, the volcanoes would vent into ocean directly and the depth of the water might suppress the whole cycle. Or so it was thought.
However, recent research suggests that waterworlds, at least 10% more than earth-like terrestrial worlds, would remain habitable for longer. The key in the simulations, it seems, was to have the right atmospheric mix. The water worlds would then cycle the carbon dioxide just between the ocean and the atmosphere, but over time, much like the earth-like worlds, it would draw down the CO2. One of the keys, though, was not to have too much of the planet's crust and minerals dissolved in the world ocean. Those would react with the CO2 and draw down the carbon in the atmosphere much faster.
So, a stable climate. Much more likely than we thought. Finger pulled, Sky Father.
Wait...another finger? Why?
One of the potential problems with water worlds is the oceans might dilute nutrients life needs far too much. It has been hypothesized here on earth that complex life was delayed in its development because of a lack of certain trace elements. Molybdenum was one such that took a long time to build up enough for complex life to develop. Maybe. If that is the case, then water worlds will have serious problems providing enough nutrients in the water for life. Or will they?
We will wait to see, but that Sky Father seems to be wiggling another finger at us suggests more surprises are waiting.
https://www.eurekalert.org/pub_releases/2018-08/uoc-wwc083018.php
