Civilizations are best when set up near bodies of water due to it's accessibility for fishing, irrigation, rich soil for farming and planting, traveling, exporting and importing goods (trading ports) and providing a main source of water for citizens. Both areas had that yet the Nile River Valley was known for over flooding and being primarily dry other than the floods while life near the Indus River did not normally flood and had advanced technology for it's time period. You could probably debate either but I would say the Indian subcontinent since it has proved to be easy to develop and had many desirable traits to the British during the imperialism time period.
Explanation: Because the more supplies needed in a small period of time will increase the price because more people will need those items so they will cost more.
My Idea of reducing the temperature of the world be creating more solar energy, so people don't have to electricity a lot. They can save more money by reducing rhe amount of electricity they use on a daily basis