No matter what mankind proactively or reactively does or doesn't do, sea levels shall continue to rise indefinitely. Even if the Milankovitch Effect fortuitously cycled in our favor towards cooling in conjunction with heroic human efforts to stop CO2 emissions, it'd be hundreds of years before any stabilization could occur.
Indeed, mankind could magically totally vanish off of the face of the Earth tomorrow and, still, the ice of Greenland and Antartica would continue to melt and the oceans acidify. However, dramatic action to reduce fossil fuel use would at least slow the progress of global warming's future effects.
Note: The oceans and forests are now absorbing less CO2 than before -- meaning that, in order to reduce CO2 levels, we have to reduce emissions ever more drastically.
13 Misconceptions About Global Warming (7 minutes)