Environmental Science Fundamentals Flashcards

Which of the following is a direct consequence of permafrost thaw in the context of greenhouse gas emissions?

Answer: Release of previously frozen organic carbon as CO₂ and CH₄

As permafrost thaws, ancient organic matter decomposes and releases stored carbon as CO₂ (aerobic) and CH₄ (anaerobic), creating a significant positive feedback to climate warming.

What is the 'missing carbon sink' problem in global carbon budget accounting?

Answer: A discrepancy where calculated emissions exceed measured atmospheric increases, implying unidentified uptake

Global carbon budgets show that known atmospheric increase plus ocean uptake does not fully account for anthropogenic emissions, suggesting terrestrial ecosystems (likely northern forests and soils) absorb the residual 'missing' carbon.

Which human land-use activity is currently the second-largest source of anthropogenic CO₂ emissions globally?

Answer: Deforestation and land-use change

Land-use change, primarily tropical deforestation, is the second-largest source of anthropogenic CO₂, accounting for roughly 10-15% of global emissions after fossil fuel combustion.

What does the Keeling Curve measure and why is it significant for carbon auditing?

Answer: Continuous atmospheric CO₂ concentration at Mauna Loa since 1958

The Keeling Curve is the longest continuous record of atmospheric CO₂ concentration, measured at Mauna Loa since 1958, providing the definitive evidence of rising CO₂ and its seasonal variation.

In environmental science, 'tipping points' in the climate system refer to what?

Answer: Thresholds beyond which a system shifts abruptly and potentially irreversibly to a new state

Climate tipping points are critical thresholds where small perturbations can trigger self-reinforcing changes leading to rapid, large-scale, and potentially irreversible shifts in Earth system components.

Which atmospheric process is responsible for the seasonal oscillation visible in the Keeling Curve?

Answer: Annual cycle of Northern Hemisphere plant growth and dormancy

The seasonal sawtooth pattern in the Keeling Curve reflects Northern Hemisphere vegetation: plants absorb CO₂ during spring/summer photosynthesis (CO₂ dips) and release it via decomposition in fall/winter (CO₂ rises).

What is the primary mechanism by which forests provide 'ecosystem services' relevant to climate change mitigation?

Answer: Sequestering atmospheric carbon in biomass and soil organic matter through photosynthesis

Forests sequester carbon by capturing atmospheric CO₂ through photosynthesis and storing it in wood, roots, litter, and soil, making forest conservation a key natural climate solution.