Incorrect.
Since the ice age began 3 million years ago, ocean levels primarily fluctuate due to glacial-interglacial cycles. During glacial period, vast amounts of water are trapped on land as ice, lowering sea levels, while warmer periods caused ice sheets to melt, raising ocean levels.
Slower, changes in ocean basin shape and volume due to plate tectonics also influence sea levels but over very long timescales.
Key drivers of sea level change over this period include:
- Glacial-Interglacial Cycles: During the last 1 million years, Earth experienced regular shifts between cold ice ages and warmer interglacials. When glaciers covered large parts of the Northern Hemisphere, global sea levels dropped by roughly 120–130 meters.
- Ice Sheet Melting/Formation: The freezing and melting of massive ice sheets, specifically in Antarctica and the Northern Hemisphere, directly affects the volume of water in the ocean.
- Thermal Expansion: As the climate warmed between ice ages, the water in the ocean expanded, contributing to rising sea levels.
During the last ice age, ocean levels were about 400 feet (122 meters) lower than they are today. Conversely, during warmer periods, such as 125,000 years ago, seas were significantly higher than they are now.
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