Answer:
The past climate was cooler than today.
Step-by-step explanation:
There are three naturally occurring isotopes of oxygen - O-16, O-17, and O-18, where the 16, 17 and 18 refer to the atomic mass.
The ratio of 0-16 to O-18 is used to determine the temperature using the seafloor sediments in the following manner:
1. O-18 is two neutrons heavier than O-16 and thus the water molecule in which it occurs is heavier. Due to this more energy is required to vaporize water having O-18 than water having O-16. Further water with O-18 liberates upon condensation and water with )-16 diffuses more rapidly.
2. Due to a lesser amount of energy required for the vaporization of water with O-16, the first water vapor formed during evaporation of liquid water is rich in O-16, and the residual liquid is rich in O-18.
3. As a result upon condensation of water vapor H2O-18 preferentially enters the liquid, while H2O-16 gets concentrated in the remaining vapor.
4. As an air mass moves from a warm region to a cold region, water vapor condenses followed by precipitation resulting in the removal of H2O-18, leaving behind more H2O-16 enriched water vapor causing precipitation to have lower 0-18 to O-16 ratio with a decrease in temperature.
Thus, the result of the analysis proves that the past climate was cooler than today.