CIP session 2: Climate Scenarios and Risk

Question 1

Feedback mechanisms that amplify global warming

Answer 1

Uncertainty in feedbacks is the prime reason for uncertainty in future global mean temperature projections.
Water vapor feedback
ice-albedo feedback
cloud feedback

Question 2

Essence of Climate models (how are they “made”)

Answer 2

based on conservation laws. There is discretization in space (boxes) and time (timesteps). What leaves one box must enter the other.

Question 3

Why is resolution important?

Answer 3

Any subgrid process (i.e. a process operating at smaller temporal or spatial scale) cannot be resolved. It needs to be parameterized. This may cause uncertainty. (e.g. tropical cyclones are small and cannot be resolved by most climate models)

Question 4

Emergent properties

Answer 4

large-scale features of climate systems naturally emerge (e.g. trade winds and jet streams)

Question 5

Cloud feedbacks/ uncertainty reason

Answer 5

clouds affect many parts of the climate system (radiation, wind patterns and temperature distribution). They happen at a micro-scale and cannot be resolved

Question 6

simple phyiscal drivers of extreme weather

Answer 6

-Shift in mean to warmer values will increase the frequency of heat extremes
-Warmer air can hold more water vapor (7% per 1 degree). There also more water in the air, means more water can fall down so more precipitation

Question 7

complex physical drivers of extreme weather

Answer 7

Changes to the atmopsheric circulation can strongly affect extreme weather. When temperature differences become smaller, jet streams become weaker.

Question 8

Physical drivers of increases in heatwaves

Answer 8

• Global climate shift towards higher temperatres, causes higher probability of hot weather.
• Due to slowe jet streams high pressure areas get stuck, leading to longer heatwaves.
• Heatwaves strenthen during drought because less evaporative cooling.

Question 9

How does global warming cause more extreme rainfall?

Answer 9

Wamer air can hold more water (Clausius-Clapperon equation).

Question 10

How does global warming affect hurricanes?

Answer 10

• Hurricanaes become wetter due to incresed water holding capacity of air.
• More ocean with 26+ T, hurricanes can extract more energy.
• Slowed jet streams allow for hurricanes to stay in one place longer.

Question 11

Tipping point (description)

Answer 11

A critical threshold at which the future state of a system can be qualitatively altered by a small change in forcing.