23 - Arctic Tundra Case Study - carbon sink or source?

Question 1

Is the Arctic tundra a carbon sink or source?

Answer 1

• The Arctic tundra can potentially become a source of carbon due to the feedback loop created by thawing permafrost, forest fires, and disturbances.

Question 2

What is the feedback loop caused by thawing permafrost, and what is the consequence of this loop?

Answer 2

• Thawing permafrost caused by man-made climate change can generate emissions of carbon from the tundra that cause more warming, creating a climate feedback loop.
• This feedback loop can release stored carbon into the atmosphere, potentially becoming a significant source of carbon emissions.

Question 3

What is the impact of forest fires on the Arctic tundra?

Answer 3

• Forest fires can release stored carbon into the atmosphere, potentially offsetting the impact of increased plant growth. In 2020, Arctic wildfires emitted 35% more CO2 than in 2019.
• The destruction of ancient peat bogs during wildfires can also release carbon accumulated over thousands of years.

Question 4

Can the Arctic Ocean absorb excess carbon, and what is the consequence of this?

Answer 4

• The Arctic Ocean could absorb 20% more carbon than previously predicted, potentially decimating marine life.
• As carbon dioxide in the atmosphere increases, the planet warms and more of that carbon dioxide is dissolved in the surface of the ocean.
• The increase of dissolved carbon in the ocean decreases the ocean’s pH and also decreases the concentration of carbonate ion, which is essential for the shells and skeletons of calcifying organisms.

Question 5

What is the role of forests and ecosystems in the carbon cycle of the Arctic?

Answer 5

• Forests and ecosystems play a major role in the carbon cycle of the Arctic. As forests and ecosystems in the northern hemisphere draw in and release CO2, the concentrations of CO2 rise and fall each year by about two parts per million.
• Evergreen shrubs and trees migrating northward in response to warming, absorbing and releasing more CO2 than the tundra vegetation they replace, can alter atmospheric CO2 concentrations.

Question 6

How can wet soils potentially act as a carbon sink?

Answer 6

• Water-saturated soils can immobilize carbon for a longer time in a warmer climate. Some studies have found that if the soil is soaked in lots of water, it can retain its load of carbon for centuries.
• The living conditions for tiny, carbon-consuming bacteria in the soil are a crucial factor for consideration in climate models.
• However, there are uncertainties around the increased rates of methane emissions that we can expect from additional permafrost thaw.