Untitled Flashcards Set
Q: What is the relationship between the temperature a mineral begins crystallizing at (Bowen’s Reaction Series) and its stability at the Earth’s surface (Goldich’s Weathering Series)?
A: Minerals that crystallize at high temperatures (early in Bowen’s Reaction Series) are the least stable at Earth’s surface conditions and weather the fastest. Conversely, minerals that crystallize at lower temperatures are more stable and weather more slowly.
Q: Why are some people proposing we grind up basalt and spread it on farm fields?
A: Because basalt contains minerals that weather quickly, reacting with CO₂ in the atmosphere and removing it through chemical weathering, a process that ultimately stores carbon in soils and ocean sediments.
Q: How might we use ground-up minerals to accelerate CO₂ removal from the atmosphere?
A: By spreading finely ground silicate rocks (like basalt) on land, we enhance natural chemical weathering, which captures CO₂ and forms stable carbonate minerals or bicarbonate ions that get washed into the ocean.
Q: What is a climate forcing?
A: A climate forcing is an external factor that changes Earth’s energy balance, such as greenhouse gas concentrations, solar radiation, or volcanic eruptions.
Q: Which “knobs” on global average temperature do forcings operate on?
A: Forcings operate on the energy input and output—essentially controlling how much energy enters and leaves the climate system.
Q: What is a climate feedback?
A: A feedback is a process that amplifies or dampens the effects of a climate forcing, such as ice-albedo feedback or water vapor feedback.
Q: Which “knobs” on global average temperature do feedbacks operate on?
A: Feedbacks affect how the climate system responds internally—adjusting the system’s sensitivity to initial forcings.
Q: How do you distinguish examples of forcings from feedbacks?
A: Forcings are external drivers (e.g., CO₂ emissions), while feedbacks are internal responses (e.g., melting ice increasing warming).
Q: What is equilibrium climate sensitivity (ECS)?
A: ECS is the amount of global average surface warming expected if atmospheric CO₂ doubles and the climate system comes to equilibrium with that change, excluding very long-term feedbacks.
Q: What is the most likely value for Earth’s equilibrium climate sensitivity?
A: About 3 °C (5.4 °F) of warming for a doubling of CO₂.
Q: What is the likely range of values for Earth’s equilibrium climate sensitivity?
A: Between 2 °C and 5 °C of warming for a doubling of CO₂.
Q: How much direct warming would a doubling in atmospheric CO₂ concentration cause?
A: About 1 °C of direct radiative warming.
Q: How much indirect warming would a doubling in atmospheric CO₂ cause after fast-acting feedbacks take effect?
A: About 2 additional °C, leading to around 3 °C total warming.
Q: How much indirect warming would a doubling in atmospheric CO₂ cause after slow-acting feedbacks take effect?
A: Possibly an additional 1–3 °C, bringing the total to 4–6 °C or more over millennia.
Q: Why is the Earth slow to respond to changes in its radiation balance?
A: Because of the large thermal inertia of the oceans and ice sheets, which take centuries to millennia to fully respond to warming.
Q: How long have we known about Earth’s slow response to changes in its radiation balance?
A: Scientists have recognized this since the mid-20th century through models and paleoclimate studies.
Q: How can we estimate Earth’s climate sensitivity?
A: Through observational data, climate models, paleoclimate reconstructions, and energy budget constraints.
Q: Are Earth’s climate-system feedbacks positive or negative on balance?
A: Positive on balance, meaning they tend to amplify initial warming.
Q: What’s the probability that Earth will warm less than 1 °C from a doubling of CO₂?
A: Very low—less than 5%.
Q: What’s the probability that Earth will warm more than 6 °C from a doubling of CO₂?
A: Low, but non-negligible—likely less than 10%, but still significant.
Q: What issue is the “crux” of the scientific debates around climate change?
A: How much warming we will get in the future, especially given uncertainties in climate sensitivity and feedbacks.
Q: How much future warming will we get?
A: It depends on emissions pathways and feedbacks, but likely between 2–4 °C for a doubling of CO₂.
Q: What is Earth-system sensitivity?
A: It’s a broader concept than ECS that includes both fast and slow feedbacks (like changes in ice sheets and carbon cycle feedbacks).
Q: What is the most likely value for Earth-system sensitivity?
A: Around 5 °C of warming for a doubling of CO₂, though estimates vary.
Q: What’s a bottom-line message about the relationship between atmospheric CO₂ and Earth’s surface temperature?
A: As CO₂ concentrations rise, Earth’s surface warms, with the amount of warming determined by both direct effects and feedbacks in the climate system.