Untitled Flashcards Set

What is the relationship between the temperature a mineral begins crystallizing at and its stability at the Earth's surface?

Minerals that crystallize at high temperatures are the least stable at surface conditions and weather quickly, while those that crystallize at lower temperatures are more stable and weather slowly.

Why are some people proposing we grind up basalt and spread it on farm fields?

Basalt contains minerals that weather quickly, reacting with CO₂ and removing it from the atmosphere, thus storing carbon.

How might we use ground-up minerals to accelerate CO₂ removal from the atmosphere?

By spreading finely ground silicate rocks on land to enhance natural chemical weathering, capturing CO₂ and forming stable carbonate minerals.

What is a climate forcing?

A climate forcing is an external factor that alters Earth’s energy balance, like greenhouse gas concentrations.

Which 'knobs' on global average temperature do forcings operate on?

Forcings control the energy input and output in the climate system.

What is a climate feedback?

A feedback is a process that amplifies or dampens the effects of a climate forcing.

Which 'knobs' on global average temperature do feedbacks operate on?

Feedbacks adjust the internal sensitivity of the climate system to initial forcings.

How do you distinguish examples of forcings from feedbacks?

Forcings are external drivers like CO₂ emissions; feedbacks are internal responses like melting ice.

What is equilibrium climate sensitivity (ECS)?

ECS is the expected global warming if atmospheric CO₂ doubles and the climate system reaches equilibrium, excluding long-term feedbacks.

What is the most likely value for Earth’s equilibrium climate sensitivity?

About 3 °C (5.4 °F) for a doubling of CO₂.

What is the likely range of values for Earth’s equilibrium climate sensitivity?

Between 2 °C and 5 °C of warming for a doubling of CO₂.

How much direct warming would a doubling in atmospheric CO₂ concentration cause?

About 1 °C of direct radiative warming.

How much indirect warming would a doubling in atmospheric CO₂ cause after fast-acting feedbacks?

About 2 additional °C, totaling around 3 °C.

How much indirect warming would a doubling in atmospheric CO₂ cause after slow-acting feedbacks?

Possibly an additional 1–3 °C, leading to a total of 4–6 °C over time.

Why is the Earth slow to respond to changes in its radiation balance?

Due to the large thermal inertia of oceans and ice sheets, which respond over centuries to millennia.

How long have we known about Earth’s slow response to changes in radiation balance?

Scientists have recognized this since the mid-20th century through models and paleoclimate studies.

How can we estimate Earth’s climate sensitivity?

By using observational data, climate models, paleoclimate reconstructions, and energy budget constraints.

Are Earth’s climate-system feedbacks positive or negative on balance?

Positive on balance, meaning they tend to amplify warming.

What’s the probability that Earth will warm less than 1 °C from a doubling of CO₂?

Very low—less than 5%.

What’s the probability that Earth will warm more than 6 °C from a doubling of CO₂?

Low but non-negligible—likely less than 10%.

What issue is the 'crux' of the scientific debates around climate change?

The amount of future warming, particularly uncertainties in climate sensitivity and feedbacks.

How much future warming will we get?

Likely between 2–4 °C for a doubling of CO₂, depending on emissions pathways.

What is Earth-system sensitivity?

A broader concept than ECS, including both fast and slow feedbacks like ice sheets and carbon cycle changes.

What is the most likely value for Earth-system sensitivity?

Around 5 °C of warming for a doubling of CO₂.

What’s a bottom-line message about the relationship between atmospheric CO₂ and Earth’s surface temperature?

As CO₂ concentrations rise, Earth’s surface warms, influenced by both direct effects and feedbacks.