Question

The greenhouse effect has both negative and positive consequences for the Earth. In two or three well-developed paragraphs, define the greenhouse effect and explain how it is helpful to the planet Earth.

Answer 1

as for defining greenhouse effect: http://www.epa.gov/climatestudents/basics/today/greenhouse-effect.html
as positive factors you could do making sure we don´t freeze (without the greenhouse effect the temperature on earth would be about -32 C)
as negative factors you could write about the runaway greenhouse effect possibly eliminating life on earth

Answer 2

ok ty