Environmental Science Fundamentals Flashcards

Which term describes the total stock of carbon stored in all living and dead organic matter in a forest ecosystem?

Answer: Carbon stock

Carbon stock refers to the total quantity of carbon held in a reservoir (e.g., living trees, deadwood, litter, soil) at a given point in time, measured in tonnes of carbon.

The 'water vapor feedback' in climate science refers to which process?

Answer: Rising temperatures increasing atmospheric water vapor, amplifying warming

As temperatures rise, more water evaporates into the atmosphere; since water vapor is itself a greenhouse gas, this further amplifies warming — the strongest positive climate feedback.

Which soil type stores the most carbon per unit area globally?

Answer: Peatlands and organic soils (histosols)

Peatlands (histosols) store vast amounts of carbon because waterlogged, anaerobic conditions slow decomposition; though covering only 3% of land, they hold about 30% of all soil carbon.

What is 'eutrophication' and why is it relevant to carbon auditing?

Answer: Excess nutrient runoff causing algal blooms that deplete oxygen and release CO₂ and CH₄

Eutrophication from nitrogen/phosphorus runoff triggers algal blooms; when algae die and decompose, microbial activity consumes oxygen and releases CO₂ and CH₄, creating greenhouse gas sources in water bodies.

In the context of the Paris Agreement, what is the significance of a 1.5°C versus 2°C warming target?

Answer: Limiting to 1.5°C significantly reduces risks of extreme weather, sea-level rise, and ecosystem loss compared to 2°C

IPCC reports show that limiting warming to 1.5°C rather than 2°C significantly reduces projected risks including coral reef die-offs, Arctic sea-ice loss, extreme heat events, and sea-level rise.

Which natural Earth system process is primarily responsible for drawing down CO₂ concentrations over geological timescales (millions of years)?

Answer: Weathering of silicate rocks

Chemical weathering of silicate rocks consumes CO₂ from the atmosphere as carbonic acid reacts with minerals, ultimately depositing carbon in marine sediments — the long-term geological carbon thermostat.

What does the term 'carbon residence time' refer to in Earth system science?

Answer: The average time a carbon atom spends in a particular reservoir before moving to another

Carbon residence time is the average time a carbon atom remains in a given reservoir (e.g., ~5 years in the atmosphere for a molecule of CO₂ to exchange with land/ocean, but centuries to millennia for full equilibration).