Step 1: Recalling the Text:
The essay frames Antarctica as uniquely valuable across all three timeframes of Earth's environmental history.
Step 2: Explaining the Significance:
Its ice-core data reveals ancient atmospheric conditions, its current isolation from large-scale human interference preserves an unspoiled present-day ecosystem, and its rapid ice melt due to climate change offers a preview of the planet's likely future trajectory.
Final Answer:
Because Antarctica's ice cores hold a detailed record of the Earth's ancient climate, its unspoiled state reflects an untouched present, and its vulnerability to warming previews the planet's future, it is considered essential to visit and study to understand the Earth across all of time.