Global means “of, or relating to the entire earth, world wide” – not just our backyard.
Why have countries stopped doing above ground nuclear testing? Because they figured out that radioactive crap released in the desert eventually spreads everywhere on the planet – and could have profound effects by increasing cancers, affecting food production, causing birth defects, etc (This experience is proof that we humans really can screw up the planet if we wanted.)*
I live in a cold climate, at a higher elevation and could stand to add a few degrees F to my backyard. My heat bill would go down and my winters would be nicer. And hopefully I won’t have snow in April! But…
I live in the US where we support other people in the country and planet. A flood in NJ will increase my insurance rates. An oil spill in Louisiana will increase the price of my shrimp dinner. A building washed into the water in Florida will put people out of work and increase the unemployment tax I pay into the system. Unless we live in a shack off the grid, grow all our own food, pay no taxes, and make our power, we are all related.
Sure we can put on blinders and only look in our backyards so we don’t see it. But one way or the other we will pay for it.
Here’s a real quick first order approximation of numbers for you. The coefficient of thermal expansion of water is 0.000038 / deg F. (38×10–6). The average depth of the ocean is 14,000 ft. 8th grade math problem how much does sea level rise if the ocean temperate increases 1 deg F? Ans: 0.53 ft. Of course some places the temperature does not go up only 1 degree. In other places the ocean is deeper. but these are just average numbers to get a feel for it. A 4 degree F rise in temp would mean 2 ft. I would not be buying land in Nauru, Tuvalu, or the Marshall islands.
*Not to derail the tread but a good friend of mine is a nuclear physicist researching exotic particles His experiments are extremely sensitive and require steel with no residual radioactivity. No problem right? Wrong! Every piece of steel above ground or made since 1945 has higher background radiation than he can use. They need to use steel from old scrapped and abandoned structures that have been under the water since before 1944. It then has to be processed in a special facility so they can use it.