If the greenhouse effect causes the Earth's average temperature to increase by a total of 3°F between the years 1960 and 1990, what is the rate of temperature change in degrees per year (°F/year)?

0.10 °F/year

Explanation:

rate of temperature change in degrees per year is calculated by  

dividing the total change in temperature by no. of years in which that change if temperature took place.

rate of temperature change = total change in temperature/no. of years

given

period of years = 1990-1960

no. of year = 1990-1960 = 30 years

total change in temperature = 3°F

the rate of temperature change = 3°F/30 years = 0.10 °F/year

the rate of temperature change is 0.10 °F/year.