Global temperatures are rising. Many have talked of discomfort and dislocation in regard to climate change, but let's at least start to face this hard fact: It is entirely possible that global warming may kill off the human race. When the day time high hits 170 degrees in Phoenix, anyone still living there will drop dead as soon as they step into the heat. That day could be as soon as 50 years away.
In the meantime, people will begin moving north. The temperatures will be (relatively) cooler, and, in most cases, a water supply will still be available. Even at that, Minneapolis or Calgary (then) is likely to be hotter than anyplace on earth at the present time.
Desert cities will become ghost towns as will a good number of towns and villages in more arid locations, including the Amazon basin, India, parts of Africa, China, Australia and the south-eastern US. Global warming could get so bad that even northern climes become uninhabitable. If that should happen, the human race would be doomed.
The demise of the human race would be a calamity for all life on earth. The sun will eventually expand and doom our planet. As the sun gets bigger, all water will evaporate from the earth. We need to find another planet, one which can sustain human and animal life, and we have about 300,000 to do it. If we haven't found a way off planet earth by then, no life will survive.
At present, humans are the only earthly beings scientifically advanced enough to find a way off this planet in 300,000 years. Given enough time, dolphins, or perhaps bees, could take over and find a way to do it, but 300,000 years is probably not enough time for that evolution to take place. Therefore, it's up to us not to kill ourselves off before we have a chance to make the move to another planet.
What are the odds?