Question

During glacial periods, why did the levels of CO2 remain low?

a) Reduced volcanic activity
b) Increased biological activity
c) Enhanced industrial emissions
d) Higher absorption by ocean water due to lower temperatures

Answer 1

The levels of CO2 remained low during glacial periods mainly due to the higher absorption by colder ocean waters; colder temperatures allow oceans to dissolve and retain more CO2, contributing to the colder climate.

Step-by-step explanation:

During glacial periods, the levels of CO2 remained low primarily due to higher absorption by ocean water because of lower temperatures (d). When the Earth's temperatures decline, the ocean waters become colder and can dissolve more carbon dioxide. This leads to less CO2 in the atmosphere, which helps maintain or further cool the climate, contributing to glacial periods. In contrast, factors like increased geological activity - which includes volcanic eruptions - would typically release more CO2 into the atmosphere, not less, contrasting with the conditions during a glacial period.