Impacts of carbon cycle: Ocean

Question 1

overview

Answer 1

It is difficult to predict the precise rate, magnitude and direction of change of Co2 uptake and how it affects acidity, salinity, storminess and nutrient enrichment. It is even more difficult to map these effects on a local scale.

Carbon can be converted into calcium carbonate, which is used by some marine organisms to build shells.

Question 2

Ocean acidification 1

Answer 2

30% of the released co2 is diffused into the ocean through direct chemical exchange.

This creates a carbonic acid, making the ocean less alkaline

Since 1750, the pH of the oceans surface has dropped by 0.1.

Question 3

Ocean acidification 2

Answer 3

Carbonic acid reacts with carbonate ions in the water to form bicarbonate.

However, animals like coral and phytoplankton need those ions to make their shells. Less carbonate available may mean shells become thinner and more fragile.

Coral reefs provide food and livelihood security for 500 million people. A fall in marine biology threatens food security.

Question 4

Ocean warming

Answer 4

Could reduce the abundance of phytoplankton, which grow better in cool, nutrient-rich waters.

Thus reducing the oceans ability to take carbon from the atmosphere through the biological carbon pump and lessen the effectiveness of oceans as a carbon sink.

However, Co2 is essential for phytoplankton growth and could therefore encourage it.
Ocean warming kills off the symbiotic algae which coral needs in order to grow, leading to coral bleaching and eventual coral deaths.

Question 5

Melting sea ice

Answer 5

Melting ice is part of a feedback mechanism: Highly reflective ice is replaced by more absorbent water. This then absorbs more sunlight which in turn amplifies the warming.
Sea ice also provides a habitat for algae. The loss affects the food chain from krill to bears.
Seals and bears can no longer travel on the ice.

Question 6

Sea level rise

Answer 6

Since the 1990s, sea levels have risen at a rate of 3.5mm/year.
Caused by melting sea iCe and thermal expansion.

Increased melting of ice and drop in snowfall in shorter winters results in an imbalance 🡪

net gain of water entering the ocean.
Thermal expansion: When water heats up, it expands.
About half of the past century’s rise in sea level is attributed to the oceans having a greater volume.
If continued, oceans are expected to rise between 0.8 and 2mm PER YEAR by 2100.

Question 7

Ocean salinity

Answer 7

Decrease in salinity in the deep North Atlantic, probably caused by higher levels of 🌧 and 🌡

More freshwater being added to the ocean

Slowing down of the large-scale oceanic circulation in the NE Atlantic.