CCP Climate Change Science & Modeling 2 — Questions and Answers
Question 1: What does the term 'radiative forcing' measure in climate science?
- The rate of infrared radiation emitted by Earth's surface
- The net change in energy flux caused by a driver of climate change (Correct answer)
- The amount of solar radiation absorbed by the oceans
- The difference in temperature between the poles and equator
Correct answer: The net change in energy flux caused by a driver of climate change
Radiative forcing quantifies the net change in energy flux (W/m²) in the atmosphere caused by a climate driver such as greenhouse gases or aerosols.
Question 2: Which feedback mechanism causes Arctic sea ice loss to amplify warming by exposing darker ocean water?
- Planck feedback
- Ice-albedo feedback (Correct answer)
- Lapse rate feedback
- Water vapor feedback
Correct answer: Ice-albedo feedback
The ice-albedo feedback occurs because dark ocean water absorbs more solar radiation than reflective ice, amplifying warming as ice melts.
Question 3: In climate models, what is a 'parameterization'?
- A method for measuring atmospheric CO₂ concentrations
- A mathematical representation of processes too small or complex to resolve explicitly (Correct answer)
- The calibration of temperature sensors in climate stations
- A statistical technique for downscaling global model output
Correct answer: A mathematical representation of processes too small or complex to resolve explicitly
Parameterization represents sub-grid-scale processes (such as convection or cloud microphysics) using simplified equations based on observable large-scale variables.
Question 4: What is the primary driver of the observed increase in global mean sea level over the past century?
- Increased river runoff from deforestation
- Thermal expansion of seawater and melting of land ice (Correct answer)
- Subsidence of ocean floor basins
- Decreased ocean salinity reducing density
Correct answer: Thermal expansion of seawater and melting of land ice
Both thermal expansion of warming ocean water and the melting of glaciers and ice sheets contribute roughly equally to observed sea level rise.
Question 5: Which greenhouse gas has the highest Global Warming Potential (GWP) over a 100-year horizon per unit mass?
- Carbon dioxide (CO₂)
- Methane (CH₄)
- Nitrous oxide (N₂O)
- Sulfur hexafluoride (SF₆) (Correct answer)
Correct answer: Sulfur hexafluoride (SF₆)
SF₆ has a GWP of approximately 23,500 over 100 years, making it the most potent greenhouse gas by mass on this timescale.
Question 6: The Milankovitch cycles describe variations in Earth's orbit that operate on timescales of:
- Decades to centuries
- Hundreds to thousands of years
- Tens of thousands to hundreds of thousands of years (Correct answer)
- Millions to billions of years
Correct answer: Tens of thousands to hundreds of thousands of years
Milankovitch cycles—eccentricity (~100,000 yr), obliquity (~41,000 yr), and precession (~23,000 yr)—operate over tens to hundreds of thousands of years and drive glacial-interglacial cycles.
Question 7: What does a positive climate sensitivity value indicate?
- The climate system will cool in response to increased CO₂
- Surface temperatures will rise in response to increased radiative forcing (Correct answer)
- Ocean heat uptake will decrease as temperatures rise
- Aerosol forcing will dominate over greenhouse gas forcing
Correct answer: Surface temperatures will rise in response to increased radiative forcing
A positive equilibrium climate sensitivity means the planet warms in response to increased radiative forcing, such as doubling CO₂.
CCP Climate Change Science & Modeling 2
What does the term 'radiative forcing' measure in climate science?