Climate shifts are natural for the Earth. This climate shift is also natural and is unrelated to the CO2 levels. Proof? For proof of previous climate shifts to prove that the Earth's climate naturally fluctuates please wiki the "Medieval Warm Period" and "The Little Ice Age."
Please note that we did not have CO2 emitting power plants in the Medieval Period. Please note that the Little Ice Age began declining before the industrial revolution. Please note that during THE ICE AGE not the Little Ice Age but the famous Ice Age with the Mammoths and such that CO2 levels were much much higher than they currently are.
Even if we were to regard the menace of Global Warming as real, it would not be as tragic as you think. Plants take in CO2 and emit O2 or the very air that sustains all living creatures: Oxygen. Therefore, with a surplus of CO2 all those trees that eco-geeks cry about will thrive. Also, as for your dreaded flooding, if the basic survival instincts still in animals exist in humans we'll have the sense to move away from the ocean as the ocean rises from any icecap melting.
Also note that because of the icecap melting new lands will be available for humans. Nearly unlimited resources of oil in the arctic spots of the world will finally be available for extraction. Those horrific gas prices we currently pay will drop to barely anything.
In short, climate change is a natural occurrence on the Earth. However, if you do not believe that, then that's fine because global warming is a good thing. Thank you for your time and again here are good searches for wikipedia.
"Medieval Warm Period"
"Little Ice Age"