<span>the answer is energy is not created nor destroyed, but it can change from one energy form to another.</span>
Answer: 
Explanation:
The equation to calculate the center of mass
of a particle system is:

In this case we can arrange for one dimension, assuming the geometric center of the Earth and the ladder are on a line, and assuming original center of mass located at the Earth's geometric center:

Where:
is the mass of the Earth
is the mass of 1 billion people
is the radius of the Earth
is the distance between the center of the Earth and the position of the people (2 m above the Earth's surface)

This is the displacement of Earth's center of mass from the original center.
Work done is given by product of force and displacement due to that force
So here we will have

here we know that


Now work done is given as


so it will do 16 J work to move the box
The temperature on the Earth would increase.
The temperature of the stratosphere would decrease.