So, you don't think the whole world will flood because water has an index of refraction that varies with frequency? Wow. That's pretty screwy.
But at any rate, nobody seriously believes the entire world will flood anyway. The most that can reasonably happen is a sea level rise of ~80-100 meters or so. And that would take many centuries to occur, and would require truly massive warming.
Actually that could happen in as little as a century.
What we are worried about instead is sea level rise over the next few decades (~30-50 years) that is enough to cause serious problems for many coastal cities, such as dramatically increased chance of flooding during storms.
The rise in sea level is just the side show. Arctic warming will disrupt the atmospheric equatorial to polar flow. The jetstream has already retreated northward by 1 degree. With the equatorial polar flow stopped the monsoons will cease meaning droughts over southeast Asia, and in Africa. That means crop failures, starvation, and monkey fights.
Models also show that hurricanes are to be looked for in the Mediterranean, as well as in the south Atlantic. Climatologists may disagree about time lines, but almost all agree that it will happen.
What makes the future so hard to predict is that there are so many related variables, that are poorly understood and described by differential equations that we cannot solve exactly. Droughts lead to forest fires and crop failures which put even more greenhouse gasses into the atmosphere. Warmer oceans put out more CO2 and methane. That will also shut down ocean circulation, so that England for instance will freeze before its total ruin is emphasized by a northward march of the subtropical desert.
Surface warming of the oceans will stop the upwelling of nutrients from the cold depths meaning massive die-offs of phytoplankton, and taken with the vanishing of the rainforests that will mean less oxygen in the atmosphere. That will mean even less carbon fixation leading to even more warming. We have already overfished the oceans and the die-off of phytoplankton, the base of the food chain will likely render the oceans lifeless.
The Sahara will probably get more rain for a while, but there is no vegetation to hold the water so all that would happen would be that all that sand would get washed off the bedrock. Thing of subtropical desert extending all the way to the Canadian border. We've already draw down that aquifer, so the bread basket will become a sandbox.
It is not just going to get hotter over the short run. It is going to be completely unpredictable. But the bottom line is this: Several thousand years ago a drop in temperature of only five degrees below present norms caused human populations to fall from hundreds of thousands to about seven thousand. But even massive vulcanism would cause the ground to cool and crops to fail even as the atmosphere continued to rise. So even if we devise a solar shade it will mean crop failures on a massive scale.
We live in a very limited box of tolelrable climatic conditions. Just a bit outside that box and we are trying to live on a Mars-like Earth or a Venus-like Earth.
I believe that humans are too lazy, greedy, and ignorant to do anything about climate change until it is too late. It is already too late to stop the change, and billions are going to die. If we continue to burn fossil fuels and overpopulate the Earth with humans the species will become extinct, dead of its own greed and slothful ignorance.
And if there is a just God, future generations, what there are of them will curse us before his face.
