A few further thoughts: 1. 4 Bn tonnes of Uranium is roughly a cube of 580m, yes it would sink, I think the concentration has diminished over time so that it w

A few further thoughts: 1. 4 Bn tonnes of Uranium is roughly a cube of 580m, yes it would sink, I think the concentration has diminished over time so that it wouldn't start to fission. 2. Removing it from the ocean would reduce the concentration and so make it more difficult to remove more. 3. If only we could do something like this to remove CO2 from the ocean since its in balance with the atmosphere. Adding an alkali to the ocean could mop up some CO2. 3a. There's the whole idea of spreading the Earth with simulated Whale faeces which adds the nutrients for the plankton to thrive. 3ai. Ideally the population of whales would grow to reduce that. However the population of whales will only slowly increase and whales would then be more likely to collide with freight ships (freight ships are more efficient the larger they are, perhaps that's why whales are so large) 3aii. As the populations of whales increase I'd imagine there would be more risk of whales spreading disease (what diseases do whales get?)