What process causes sea level to rise when the water is warmer?

What process causes sea level to rise when the water is warmer?

• A. Thermal expansion of seawater
• B. Increased precipitation over oceans
• C. Expansion of sea ice
• D. Ocean floor uplift

Answer: (A)

When water warms, it expands, increasing the ocean’s volume. As seawater temperature rises, its molecules move faster and take up more space, so the same mass of water occupies more cubic meters. This thermal expansion directly raises sea level, even without adding any extra water from melting ice or other sources. The other ideas don’t fit this specific link between warming and sea level rise: expanding sea ice occurs when temperatures are colder, and melting floating sea ice doesn’t noticeably raise sea level because it’s already displacing an amount of water equal to its weight. Increased precipitation over oceans adds water, but it isn’t the direct result of the water warming. Uplift of the ocean floor would not be caused by warming and would tend to lower local sea level if it occurred.

When water warms, it expands, increasing the ocean’s volume. As seawater temperature rises, its molecules move faster and take up more space, so the same mass of water occupies more cubic meters. This thermal expansion directly raises sea level, even without adding any extra water from melting ice or other sources.

The other ideas don’t fit this specific link between warming and sea level rise: expanding sea ice occurs when temperatures are colder, and melting floating sea ice doesn’t noticeably raise sea level because it’s already displacing an amount of water equal to its weight. Increased precipitation over oceans adds water, but it isn’t the direct result of the water warming. Uplift of the ocean floor would not be caused by warming and would tend to lower local sea level if it occurred.