An updated graphic has been posted… along with Earth stripped of its water, with the water rolled up into a ball, this one shows Europa with its water rolled up into a ball.
Europa, it seems, has 2 to 3 times the volume of water that Earth has.
One obvious suggestion for sci-fi: assume technology 300 years down the line… and “the line” is a nicely progressive one (based on the growth of technology that engineers and scientists can probably produce, so long as the profit motive was retained and regulators and eco-freaks were fed into phaser-based woodchippers). By that time, mankind should be practically godlike in power; moving Europa to Venus should be readily achievable. Scrape the crappy atmosphere off Venus, leave some oxygen and nitrogen, and then pour a good fraction of Europas ocean onto the surface of Venus. Take the vast amount of carbon dioxide you sucked off Venus and separate it out into oxygen and carbon; dump the carbon onto Europa, increasing its mass and volume, and use the oxygen to give it an atmosphere. Dump the excess oxygen onto the Moon and Mars to terraform them as well.
Take the sulfur from the sulfuric acid clouds you’ve removed from Venus, and use it to form a ring around Venus. Because that would be awesome.