CCP Climate Change Science & Modeling 3 — Questions and Answers
Question 1: Which component of the climate system has the largest heat capacity and therefore the greatest influence on moderating temperature change?
- The cryosphere
- The lithosphere
- The ocean (Correct answer)
- The troposphere
Correct answer: The ocean
The ocean stores ~93% of the excess heat in the climate system due to water's high heat capacity and vast volume.
Question 2: In General Circulation Models (GCMs), what does 'resolution' refer to?
- The accuracy of temperature measurements fed into the model
- The spatial grid spacing and temporal time steps used in calculations (Correct answer)
- The number of greenhouse gases included in the model
- The length of the historical record used for model validation
Correct answer: The spatial grid spacing and temporal time steps used in calculations
Model resolution refers to the size of the grid cells (horizontal and vertical) and the time step length, which determine the scale of processes that can be explicitly represented.
Question 3: What is 'climate sensitivity' most commonly defined as?
- The rate of CO₂ increase per year in parts per million
- The equilibrium global mean temperature rise from a doubling of atmospheric CO₂ (Correct answer)
- The fraction of solar radiation reflected by clouds
- The time lag between emissions and temperature response
Correct answer: The equilibrium global mean temperature rise from a doubling of atmospheric CO₂
Equilibrium climate sensitivity (ECS) is the long-term global mean surface temperature increase resulting from a sustained doubling of CO₂ relative to pre-industrial levels.
Question 4: Which process best explains why the stratosphere has cooled while the troposphere has warmed due to increased CO₂?
- Ozone depletion absorbing more UV radiation in the stratosphere
- CO₂ trapping outgoing radiation in the troposphere, reducing energy reaching the stratosphere (Correct answer)
- Increased aerosol loading reflecting sunlight at high altitudes
- Changes in the Brewer-Dobson circulation reducing heat transport
Correct answer: CO₂ trapping outgoing radiation in the troposphere, reducing energy reaching the stratosphere
Increased CO₂ absorbs more outgoing longwave radiation in the troposphere, reducing the energy available to heat the stratosphere, causing stratospheric cooling—a key fingerprint of greenhouse warming.
Question 5: What is 'ocean acidification' caused by?
- Increased acid rain from industrial sulfur emissions
- Absorption of atmospheric CO₂ forming carbonic acid in seawater (Correct answer)
- Thermal stratification reducing alkalinity in surface waters
- Runoff of agricultural fertilizers into coastal zones
Correct answer: Absorption of atmospheric CO₂ forming carbonic acid in seawater
Oceans absorb about 25% of anthropogenic CO₂ emissions, which reacts with water to form carbonic acid, lowering ocean pH.
Question 6: Which scenario framework does the IPCC AR6 use to project future climate?
- Special Report on Emissions Scenarios (SRES)
- Representative Concentration Pathways (RCPs)
- Shared Socioeconomic Pathways (SSPs) (Correct answer)
- Intergovernmental Panel on Future Scenarios (IPFS)
Correct answer: Shared Socioeconomic Pathways (SSPs)
AR6 uses Shared Socioeconomic Pathways (SSPs), which combine socioeconomic narratives with radiative forcing levels (e.g., SSP1-2.6, SSP5-8.5).
Question 7: What is the significance of the 'carbon budget' concept in climate science?
- It calculates the cost-benefit ratio of renewable energy investments
- It quantifies the total CO₂ emissions allowable to remain below a temperature target (Correct answer)
- It measures the annual flux of carbon between oceans and atmosphere
- It tracks government expenditures on climate adaptation programs
Correct answer: It quantifies the total CO₂ emissions allowable to remain below a temperature target
The remaining carbon budget estimates the maximum cumulative CO₂ emissions compatible with limiting warming to 1.5°C or 2°C, providing a science-based limit for policy.
CCP Climate Change Science & Modeling 3
Which component of the climate system has the largest heat capacity and therefore the greatest influence on moderating temperature change?