Understanding the Carbon Cycle

According to the video, how does the “dynamic equilibrium” in the biological carbon cycle manifest itself?

• It maintains lower carbon dioxide levels in warm periods and higher levels during ice ages

• It balances CO₂ absorption and emission through processes like respiration, photosynthesis, and ocean exchange

• It relies solely on marine organisms to maintain atmospheric CO₂ levels at a constant rate

Which statement best captures why atmospheric carbon dioxide levels began to surge in the late 18th century?

• Global population growth led to more people exhaling carbon dioxide

• Plants began photosynthesizing less due to climate shifts

• Industrial activity and fossil-fuel combustion introduced large amounts of previously trapped carbon into the atmosphere

Why might the oceans become less effective as a carbon sink in the future, according to the text?

• Cold water absorbs less CO₂, and climate change is cooling the oceans

• Warmer waters absorb less CO₂, reducing the oceans’ ability to draw down atmospheric carbon

• Plants in the ocean are undergoing hyper-photosynthesis, which reduces overall absorption of CO₂

In the transcript, Oliver Morton mentions that roughly half of the extra carbon emitted from fossil fuels is absorbed by Earth’s “sinks.” Why is this situation still problematic?

• Because the remaining half that goes into the atmosphere continues to warm the planet

• Because sources like volcanoes have dramatically increased in activity

• Because humans will eventually extract all underground carbon, making sinks obsolete

The video describes “negative-emission schemes.” Which of the following best characterizes their fundamental purpose?

• To accelerate the natural carbon cycle by increasing volcanic CO₂ emissions

• To remove existing CO₂ from the atmosphere, either by enhancing natural sinks or creating new ones

• To rely on chemical reactions in the atmosphere that convert CO₂ into harmless ozone

What is a key limitation of negative-emission technologies mentioned in the transcript?

• They release more methane than the amount of CO₂ they remove

• They currently operate on a small scale and would require an unprecedented economic shift to scale up

• They increase soil erosion in areas where they are implemented

Which point does the text make regarding “dynamic equilibrium” before humans began burning fossil fuels?

• Carbon was constantly increasing due to animal respiration

• Fossil carbon remained largely undisturbed underground for millions of years

• Fossil carbon was released into the atmosphere through tidal processes

The text refers to the Anthropocene as a new geological age. What criterion does it use to define this era?

• A period when volcanic activity naturally overwhelmed Earth’s carbon sinks

• A time when Earth’s carbon cycle has been dominated by human activities

• An epoch in which there has been a universal equilibrium of CO₂ concentrations

Why does the video describe relying heavily on negative emissions as “dangerous”?

• Because it encourages ongoing pollution by giving a false sense of security

• Because negative-emission technologies generate more CO₂ than they remove

• Because carbon capture only works at specific altitudes in Earth’s atmosphere

Even if all fossil-fuel emissions stopped immediately, why would atmospheric CO₂ not revert to pre-industrial levels?

• Because CO₂ reacts slowly with ozone and therefore remains permanently in the air

• Because the oceans have altered their chemical composition and now release additional CO₂

• Because the extra carbon already in the atmosphere would remain, only stabilizing rather than decreasing quickly