Question

24. What is meant by the statement ‘sea level rise is relative’? Relative to what? How can sea level be rising on the North Carolina coast but declining on the Alaskan coast if it is all one interconnected ocean?

34. Describe what problems a global increase in atmospheric CO₂ can cause for coral reef ecosystems.

Answer 1

24. Relative sea-level change is how the height of the ocean rises or falls relative to the land at a particular location. In contrast, absolute sea-level change refers to the height of the ocean surface above the center of the earth, without regard to whether nearby land is rising or falling.

The sea level off North Carolina's coast is up to 11 inches higher than it was in 1950. This increase is mostly due to ice melt, and it's causing major issues.Sea levels off Alaska's coast have been decreasing because the land beneath Alaska is rising due to shifts in the Earth's tectonic plates and a process called a glacial isostatic adjustment. As the ice melts in Alaska, it weighs less and has a weaker pull on water.

34. problems a global increase in atmospheric CO2 can cause for coral reef ecosystems are-

• A warming ocean: causes thermal stress that contributes to coral bleaching and infectious disease.
• Sea level rise: may lead to increases in sedimentation for reefs located near land-based sources of sediment. Sedimentation runoff can lead to the smothering of coral.
• Changes in storm patterns: leads to stronger and more frequent storms that can cause the destruction of coral reefs.
• Changes in precipitation: increased runoff of freshwater, sediment, and land-based pollutants contribute to algal blooms and cause murky water conditions that reduce light.
• Altered ocean currents: leads to changes in connectivity and temperature regimes that contribute to lack of food for corals and hampers dispersal of coral larvae.
• Ocean acidification (a result of increased CO2): causes a reduction in pH levels which decreases coral growth and structural integrity.