human activity threatening the carbon cycle

• What is ocean acidification primarily a result of?

  Its role as a carbon sink due to fossil fuel combustion
• Why is ocean acidification a risk for coral reefs?

  It risks crossing the critical threshold for their health
• What is the flux of carbon dioxide that diffuses from the atmosphere into the ocean?

  80 PgC/yr
• What percentage of anthropogenic CO2 emissions since 1750 has the ocean absorbed?

  30%
• What is the role of the ocean in the carbon cycle?

  The ocean acts as a carbon sink
• How is acidity measured?

  Using the pH scale
• What does a pH of 7 indicate?

  It is neutral
• What does a decrease in pH indicate about ocean water?

  It indicates an increase in acidity
• How does the pH scale function?


  It is logarithmic, with each unit representing a change in H+ ion concentration by a power of 10
• How many times more H+ ions does pH 4 have compared to pH 5?

  10 times
• What happens when CO2 dissolves in ocean water?

  Some CO2 combines with water to form carbonic acid, releasing H+ ions
• What was the ocean pH in 1990?

  1. 11
• What is the estimated ocean pH in 2015?

  1. 06
• What does a drop in pH from 8.2 to 8.1 represent in terms of H+ ion concentration?

  A 30% increase in H+ ion concentration
• What is the term for the reduction in alkalinity of ocean water?

  Ocean acidification
• Which ocean is acidifying the fastest?

  The Arctic Ocean
• Why does the Arctic Ocean acidify faster?

  Cold water absorbs CO2 faster and has limited mixing
• What do many marine organisms use dissolved CO2 for?

  To form calcium carbonate shells or skeletons
• What is the mineral form of calcium carbonate that marine organisms use?

  Calcite or aragonite
• What does carbonic acid do to shells and coral skeletons?

  It constantly attacks them, forming calcium bicarbonate that dissolves
• How do organisms maintain their shells or skeletons?

  By secreting replacement calcium carbonate
• What happens to the rate of calcium carbonate dissolution as ocean acidification increases?

  It slowly increases
• What is the threshold pH?

  The pH where calcium carbonate production matches dissolution
• What happens to organisms' shells when the threshold pH is exceeded?

  They become thinner, increasing mortality to disease and predators
• What is the coral threshold pH?

  1. 8
• What does the IPCC estimate for ocean acidification by 2100?

  A fall of 0.06-0.32 pH
• What is resilience in the context of ecosystems?

  The ability to maintain state in the face of change
• What is happening to the mussel population in the NE Pacific?

  It is declining
• What is happening to barnacles and algae populations in the NE Pacific?

  They are expanding
• What are the different types of ecosystem services?

  • Provisioning services: products obtained from ecosystems (e.g., food, fuel, medicine)
  • Regulating services: maintain biosphere suitable for human life (e.g., water purification, climate maintenance)
  • Cultural services: spiritual, recreational, educational, and scientific benefits
  • Supporting services: sustain other parts of the ecosystem (e.g., soil formation, nutrient cycling)
• How does ocean acidification threaten ecosystem services?

  It threatens biodiversity and the health of marine species that provide these services
• What percentage of marine species rely on coral reefs for habitat?

  25%
• What would be the impact of reef loss on fish supplies?

  It would threaten fish supplies (provisioning)
• How would reef loss affect coastal erosion?

  It would increase coastal erosion (regulating)
• What is the impact of species loss on the food web?

  It would have a cascade effect impacting population size, biomass production, and species diversity
• How does the reduction in calcium carbonate formation affect the carbon pump?

  It reduces the carbon pump's effectiveness, impacting climate
• What has led to contrasting regional trends in land use cover?

  Growing demand for food, fuel, and other resources globally
• How does land use change affect terrestrial carbon stores?

  It affects terrestrial carbon stores with wider implications for the water cycle and soil health
• What does the Global Footprint Network suggest for calculating environmental impact?

  I = P x A x C x T
• What do the variables in the equation I = P x A x C x T represent?

  P = population, A = affluence, C = consumer behavior, T = technology