Final Answer:
The total volume of Arctic sea and glacial ice has decreased by 1/3 since 1980.
Step-by-step explanation:
Total Volume Decrease: The statement indicates a reduction in the total volume of Arctic sea and glacial ice. The term "decreased" signifies a negative change.
Magnitude of Change: The specific quantification is "by 1/3," denoting a one-third decrease. This suggests a substantial decline in ice volume.
Timeframe: The timeframe mentioned is "since 1980," indicating the period over which the decrease has occurred. This aligns with concerns about climate change and its impact on polar ice.
Arctic Sea and Glacial Ice: The statement encompasses both Arctic sea and glacial ice, emphasizing the comprehensive nature of the ice loss, including both floating sea ice and grounded glacial ice.