To flee political unrest and to get to the U.S.A
Answer:
Greenhouse effect
Explanation:
Greenhouse effect is the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.
The lithosphere is Earth's outermost layer, composed of rocks in the crust and upper mantle that behave as brittle solids. ... The lithosphere is broken into large pieces called plates, which are made up of either seafloor lithosphere (mostly basalt) or continental lithosphere (less dense rocks, like granite).
