There is global warming because of increased CO2 and Methane in the atmosphere. The CO2 is mostly from emissions from cars and such. The Methane is mostly from cows, meaning beef and dairy. This gets trapped in our atmosphere, letting heat warm the earth but it traps the heat. This leads to an increase in temperature.
This is true.
The definition of megalopolis is that it is a large urban area, huge and densely populated. St. Petersburg is definitely one, however, Miami is relatively small compared to other megalopolises so it might not fall within that category.