Question

1. over 8 billion people on earth use water every day, yet earths water supply remains relatively constant because

a. the sea level is rising.
b. water exists in three phases on earth.
c. water is constantly recycled by the hydrologic cycle.
d. global warming melts ice and replaces water that is used
the graph below illustrates arctic sea height from 1993 to 2018.
arctic sea height, 1993–2018
sea height variation (mm)
year
based on the data in the graph, which of the following represents the approximate arctic sea level from 1995 to 2015?
a. 60 mm
b. 10 mm
c. 7 mm
d. 3 mm

Explanation:

1. For the first question about why Earth's water supply remains relatively constant despite over 8 billion people using water daily: The hydrologic cycle constantly recycles water on Earth. The sea - level rising (option a) doesn't explain the constant water supply. The three - phase existence of water (option b) is not the main reason for the constant supply. And global warming melting ice is not the key factor for the overall constant water supply compared to the hydrologic cycle.
2. For the second question about the approximate increase in Arctic sea level from 1995 to 2015 from the graph: In 1995, the sea - height variation was around 10 mm and in 2015 it was around 70 mm, so the increase is approximately 60 mm.

Answer:

1. c. Water is constantly recycled by the hydrologic cycle.
2. a. 60 mm