While some people blather on debating the existence of climate change, the climate is busily changing around us. The debate really is: Are we going to try to stop or at least reduce it, or just blunder along until the climate delivers a smackdown?
The answer should be obvious. However, here is an examination of what we could do, planet-wide, if we choose to do nothing.
First some basics: Greenhouse gasses trap heat, hence their name. Heat is energy. We are emitting CO2 and Methane at rates unparalleled in history, thus we are trapping heat in the atmosphere. Essentially we are adding energy to the weather system. Storms are getting more violent. Cold snaps are colder and more unpredictable. Rain patterns are shifting. Winds are stronger and more frequent. In general, the climate is getting a lot wilder and a bit warmer.
Areas that were reliably wet before will experience drought. Dryer areas will experience flooding. Because the climate has more energy, those areas may change between drought and flood more suddenly and less predictably. Sudden storms with strong winds and tremendous hail will become common. With the increased energy, there will be greater evaporation from the oceans, and therefore more moisture in the atmosphere altogether, but precipitation will be concentrated more extremely. Therefore where it does rain and snow, there will be greater rainfall and snowpack. On the other hand, higher winds will drive those weather patterns farther before they precipitate. In other words, floods will be deeper and droughts dryer.
How can we adapt?
Water supply: In the long run the only way to adapt will be to run tens of thousands of miles pipelines to move water from flooding areas to drought stricken areas. These areas may shift and alternate unpredictably--better make those pipes capable of flowing both ways.
Build massive offshore desalinization plants to supply fresh water to that pipe network. However, in times of flood, we may need to send water from swollen rivers and reservoirs back down the pipes into the ocean. So we’d better store the salt from the desalinization process in flotillas of barges near the pipe outlets to resalinize the fresh water when it comes back down.
Agriculture: Prepare massive seed stockpiles strategically all over the world to be able to plant whatever crops the climate of a region will support that year. Prepare to move land in and out of production or change the crops at the drop of a meteorological hat. The perfect area for rice paddies one year may be perfect for coffee the next--or cactus fruit. Forget crops that take more than one year from planting to harvest. Fruits and nuts will be in short supply, but supplanted with grains and beans.
Construct millions of square miles of roof over crops to protect them from storm damage. No matter how perfect the weather is for a crop one season, a single tornado or massive hail storm can destroy it in an afternoon. Hey while we're at it, why not put solar collectors on all those miles of roof? Might as well use some free energy to power all the water pumping.
Building: Move away from wood to nonflammable building materials like adobe, steel, and aluminum. There are two reasons for this: 1. The increasing wildfires will result in wood being in much shorter supply. 2. The increasing wildfires will endanger our structures. Better make them out of something that won’t burn.
Cities: Move all our larger cities a few miles back from watersides, or elevate the cities above the new, higher flood levels. Relocate New York City a little bit upstate, move Boston closer to to Albany, and put Miami around Gainesville. Rebuild New Orleans on very tall stilts. Also we ought to elevate our roadways, put wind breaks along both sides of every road, and both raise and strengthen ALL our bridges.
Conclusion: If we choose to do nothing to slow or stop climate change, we can just invest at most a few dozen times the combined annual economic product of the entire planet to adapt. For a few years.