Midterm

Question 1

Climate Model

Answer 1

Numerical model that calculates budgets of mass, velocity, and energy in different parts of the earth system to develop understanding

Question 2

What are the primary differences between climate models and weather forecasting models?

Answer 2

Scale (resolution and length of simulation), Climate forcings, Process representation (photosynthesis, ice melt)

Question 3

CMIP

Answer 3

Major international multi-model research activity, considered foundational element of climate science

Question 4

How does CMIP work?

Answer 4

Climate scientists from each climate modeling center use their climate model to run a set of coordinated/identical climate experiments

Question 5

What is the objective of CMIP6?

Answer 5

Better understand past, present, and future climate change arising from natural, un-forced variability, or in response to changes in radiative forcings in a multi-model context

Question 6

Pros of using multiple models:

Answer 6

Assess uncertainty in climate projections
identify robust climate response to difference climate forcings

Question 7

Why might there be a spread in projections even though each model run is using the same boundary conditions?

Answer 7

Model Uncertainty
Internal Variability

Question 8

Radiative Forcing

Answer 8

change in radiation balacne at the top of the atmo as a result of external drivers; leads to long-term changes in global temp

Question 9

Climate sensitivity

Answer 9

response of global mean surface air temp to a radiative forcing

Question 10

Equilibrium climate sensitivity (ECS)

Answer 10

response of long term global mean surface air temp to a doubling of the atmo CO2 after planetary budget is balanced

Question 11

Transient Climate response (TCR)

Answer 11

global mean surface air warming at the time of CO2 doubling in an idealized 1% year CO2 increase experiment

Question 12

Ways to estimate climate sensitivity:

Answer 12

Climate models
Recent Observations
Paleoclimate data

Question 13

Why might the use of historical period to determine ECS be a problem?

Answer 13

A major issue is the assumption that the climate feedbacks experienced during observational period remain constant over time (too low ECS value)

Question 14

Issues with Paleoclimate Records:

Answer 14

proxy record may be specific to that time period and not applicable to current/future climate
Proxies have large uncertainties

Question 15

Best Estimate of ECS

Answer 15

3C
Likely range 2.5-4

Question 16

Best Estimate of TCR

Answer 16

1.8 C
Likely range 1.4-2.2

Question 17

Climate system feedbacks:

Answer 17

a response of the climate system to a climate forcing that amplifies or diminishes the intitial effect of climate forcing

Question 18

TCRE

Answer 18

transient climate response to cumulative carbon emissions
0.8-2.5C per 1000 Gtc emitted

Question 19

What does TCRE help with?

Answer 19

allows for a direct relationship between climate targets and emission reduction efforts

Question 20

What does emergent constraints do?

Answer 20

technique to reduce “model response uncertainty”

Question 21

Emergent constraint

Answer 21

Statistical relationship across a model ensemble between a measureable aspect of the present day climate and an aspect of future pojected climate change

Question 22

Steps for identifying robust emergent constraints:

Answer 22

EC must have a plausible physical mechanism
-verify that this mechanism is at work in model ensemble
-assess whether the EC survives out-of-sample testing

Question 23

Vapor Pressure

Answer 23

pressure exerted by water molecules
corresponds with mass of water vapor (specific humidity)

Question 24

saturation vapor pressure

Answer 24

point at which the atmo becomes saturated

Question 25

Hydrologic Sensitivity

Answer 25

change in global mean precip with global surface air temp

Question 26

what does global increase in precip say about residence time of water vapor?

Answer 26

residence time of WV increases

Question 27

Emergent constraint on precipitation

Answer 27

precip must change in such a way that the energy budget of the atmosphere continues to balance

Question 28

How is change in LP balanced

Answer 28

change in radiative cooling

Question 29

how is global mean precipitation controlled?

Answer 29

availability of energy

Question 30

how is precipitation change controlled?

Answer 30

ability of the atmosphere to radiate away heat

Question 31

How does rising temperatures effect radiation?

Answer 31

causes more radiation to leave atmosphere

Question 32

How is losing radiative energy balanced?

Answer 32

there has to be a compensating increase in atmospheric latent heating associated with greater precipitation

Question 33

Global mean atmospheric moisture increases more than global mean precip, what does this imply?

Answer 33

convective mass fluxes must decrease

Question 34

Convective parameterization steps:

Answer 34

1.) assess environment state of grid cell 2.) scheme determines whether convection should happen in grid cell 3.) modifies environment state of grid cell if convection "happened"

Question 35

Initial Condition Ensemble

Answer 35

Only difference between simulations is that they are intiialized from slightly different conditions

Question 36

Attribution

Answer 36

Process of evaluating the relative contributions of multiple causal factors to a change or event with an assignment of statistical confidence

Question 37

Detection

Answer 37

process of demonstrating that climate or a system affected by climate has changed in some defined statistical sense without providing a reason for that change

Question 38

Attribution example:

Answer 38

Comparing simulated global temperature in two sets of climate model ensembles 1.) One includes observed greenhouse gas increase 2.) one does not

Question 39

Probabilistic Event Attribution

Answer 39

Quantify the change in probability of an event between model simulations of the past compared to simulations of the world had humans not interfered with climate

Question 40

Hindcast Attribution Method

Answer 40

uses highly conditioned simulations which provide strong constraints on the state of the climate so they closely match observations and then perform forecast-type simulations

Question 41

Probabilistic Event Attribution Steps:

Answer 41

1.) Decide which charateristic of the event to analyze 2.) Observational trend analysis 3.) Climate model evaluation 4.)Climate model analysis

Question 42

Groundwater Runoff

Answer 42

groundwater seeps into surface water

Question 43

surface runoff

Answer 43

movement of water across the ground; comes from infiltration excess overland flow and saturation excess overland flow

Question 44

Infiltration excess overland flow

Answer 44

from urban sources like roofs or pavements or when soil properties do not allow for infiltration to keep up with high rainfall rates

Question 45

Saturation excess overland flow

Answer 45

from precipitation or melted snow that could not be absorbed into the ground; soil is saturated keeping water from infiltrating