How will sea levels change with climate change?

Isn't the Earth simply cycling between warming and cooling all of the time. E.G.: removing/having increasingly lesser carbon dioxide produces a cooling effect which is periodically compensated for by volcanic activity. Now human activity has markedly increased atmospheric and oceanic carbon dioxide, likewise the Sun has increased in luminosity both of which may be accelerating plant growth in food crops while offsetting an ongoing natural cooling cycle? During the last Ice Age sea levels were up to 300 feet lower than today. The Earth warms and sea levels rise. OK. How do fallible humans determine just how much carbon dioxide to remove from the environment? If humans can't/won't control increasing population and/or dependency on fossil based energy, there will be new "ocean front" property. However, it will likely take a century or more to realize any effect on carbon dioxide levels. Can the lights, AC and heat be kept on? The "Horns of a Dilemma " are evident and unavoidable.