We must act timely: if we reduce greenhouse gas emissions now the sea level will rise up to 40 cm by 2100. However, if we keep this level of greenhouse gas emissions the rise will be much higher and reach about 110 cm by 2100.
Reducing greenhouse gasses will be effective on Global Warming, but the sea level will respond less timely: it will still keep rising for centuries before quitting.
Meanwhile, we must adapt to rising sea finding new solutions to protect our coasts.