According to Newton's Universal Law of Gravitation, when the distance between two interacting objects doubles, the gravitational force is

If the distance doubles, the gravitational force is divided by 4

Explanation:

Newton’s Universal Law of Gravitation

Objects attract each other with a force that is proportional to their masses and inversely proportional to the square of the distance.

Where:

m1 = mass of object 1

m2 = mass of object 2

r     = distance between the objects' center of masses

G   = gravitational constant: 6.67\cdot 10^{-11}~Nw*m^2/Kg^2

If the distance between the interacting objects doubles to 2r, the new force F' is:

Operating:

Substituting the original value of F:

If the distance doubles, the gravitational force is divided by 4

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide