# EOSC 340 LEARNING GOALS – Fall 2019 – Sept. 5, 2019

***Subject to change. The most up-to-date learning goals are within each
day’s lecture slides.***

**Course Level Goals:**

Critically EVALUATE evidence in order to explain how Earth’s climate
system works

Critically EVALUATE hypotheses on what causes climate change, including
both natural and human contributions

EXPLAIN how paleo-, historical, and modelling data all inform
predictions of future climate

Critically EVALUATE arguments made in public debate on global climate
change

Pervasive, foundational, interconnected goals:

Explain how the greenhouse effect works, in terms of energy flows

Explain when and why some components of Earth’s climate system are
“forcings” and others are “feedbacks”

Apply systems dynamics thinking (stocks, flows, amplifying and
stabilizing feedbacks, delays) to all aspects of Earth’s climate system

Evaluate uncertainty estimates for climate indicators, past, present,
and future.

*Use the goals listed here to focus your studying. Also check the
assignments and the pre-class readings/activities for learning goals.*

# Day 2: Systems – Stocks, flows and feedbacks

1. Define stock, flow, and feedback.

1. Explain how the combined history of inflows and outflows determines a
stock

1. Predict what happens to stocks and flows when a system is perturbed

1. Construct examples of both amplifying and stabilizing feedbacks

# Day 3: Blackbody Radiation

1. Use the Stefan-Boltzmann equation to compare energy emitted by objects
at different temperatures.

1. Use the Planck function to estimate thermal emission in particular
wavelength ranges.

1. Use the 2nd law of thermodynamics to prove (Kirchoff's Law)

1. Use energy balance to find the reflected, absorbed and emitted
intensities from a non-black surface.

\begin{align*}
I&=\epsilon \sigma T^4,\ I_{ref} = \alpha I_0,\ I_{tr} = tr\,I_0,\ I_{abs} = \epsilon I_0 \\
I_0 &= I_{ref} + I_{tr} + I_{abs} \\
1 & = \alpha + tr + abs
\end{align*}

# Day 4: Earth’s Radiation Balance – Incoming solar radiation and albedo

1. Apply systems dynamics concepts of stock and flow to Earth’s energy
budget.

\begin{align*}
\frac{dE}{dt} = I_{in} + I_{out}
\end{align*}

1. Figure out the incoming solar radiation for Earth and other planets

1. Compare reflectivity of different parts of the Earth system, both on the
surface and in the atmosphere.

1. Predict the impacts of altering solar energy or reflectivity on flows of
energy in Earth's climate system, and therefore Earth's temperature
(left side of Earth's energy budget diagram)

1. Classify particular changes in incoming solar radiation and albedo as
forcings or feedbacks.

1. Calculate planetary temperature response to an instantaneous forcing due
to the Planck feedback alone.

# Day 5: Greenhouse Effect I

1. Contrast how greenhouse gases interact with visible and infra-red
radiation compared to major atmospheric constituents

1. Describe what happens to photons that are absorbed and re-emitted by
greenhouse gases

1. Estimate the absorption by Earth’s atmosphere of both incoming and
outgoing radiation

1. Contrast atmospheric constituents based on their absorption spectra

1. Identify greenhouse and non-greenhouse gases based on their absorption
spectra

# Day 6: Greenhouse Effect II

1. Estimate Earth’s surface temperature from satellite data

1. Identify the absorption bands for $CO_2$, $O_3$,
$CH_4$ and $H_2O$

1. Calculate the wavelength-averaged emissivity of the atmosphere based on
the physical properties (absorption lines) of greenhouse gases.

# Day 7: Greenhouse Effect III

1. Estimate the total heating by a greenhouse gas at a specific temperature
given the absorption band and the Planck function.

1. Use intensity measurements in the atmospheric window and the 15 micron
$CO_2$ absorption band to estimate temperatures at the surface
and the top of the atmosphere

1. Use conservation of energy and Kirchoff's law to calculate the
transmitted, reflected and absorbed components of radiation through
multiple layers.

\begin{align*}
tr_{total} &= tr_1\,tr_2\,tr_3\ldots \\
abs_{total} & = 1 - tr_{total}
\end{align*}

# Day 8: Greenhouse Effect IV

1. Use stock and flow energy budgets to calculate equilibrium temperatures
in a two layer atmosphere

1. Calculate the heating rate and the greenhouse effect (in ) given short
and long wave fluxes at the surface and top of the layer.

1. Explain “band saturation” and why radiative forcing is a logarithmic
(instead of linear) function of greenhouse gas concentration.

\begin{equation*}
\Delta F = \left( 3.8 \mathrm { W } \mathrm { m } ^ { - 2 } \right) \frac { \ln ( \text {newp}
\operatorname { CO } 2 / \text { origp } \mathrm { CO } 2 ) } { \ln ( 2 ) }
\end{equation*}

1. Use the steady-state two-layer atmosphere model to explain why
increasing $C_2$ heats the planet.

**In-class Quiz 1**

# Day 9: Greenhouse Effect V

1. Explain the properties of atmospheric gases and their relative
contributions to the greenhouse effect

1. Relate concentration changes in $CO_2$ to the “fractional
doubling"

1. Calculate the change in the greenhouse effect (radiative forcing) given
an increase in $CO_2$.

1. Convert between ppm and gigatonnes carbon dioxide
Equation: 12 g C = 44 g CO2 and 7.6 gigatonnes CO2 = 1 ppm atmospheric
CO2 concentration

# Day 10: Atmospheric Temperature & Moisture

1. Use conservation of energy to calculate adiabatic temperature profiles
for moist and dry atmosphere

\begin{align*}
\Gamma = \frac{dT}{dz} = \frac{-g}{c_{p} + l_{v}\frac {dw_{v}}{dT}}
\end{align*}

1. Calculate the greenhouse effect of high and low clouds.

1. Contrast the impact of shortwave reflectivity for high and low clouds on
the total radiative forcing (including the greenhouse effect)

1. Explain the impact that convective clouds have on the vertical
temperature structure of the atmosphere and the transport of energy from
the earth's surface.

1. Explain why increased convection is a stabilizing feedback

# Day 11: Climate Sensitivity

1. Identify the major climate forcings (heating and cooling) and their
uncertainties

1. Use the heat capacity and density/mass per area of an atmospheric or
ocean layer convert between energy storage and ocean temperature
change.

\begin{align*}
\Delta E=\rho_{w} D c_{w} \Delta T
\end{align*}

1. Use energy conservation to calculate the increase/decrease of layer
energy per unit area over time:

\begin{align*}
\frac{d \Delta E}{d t}=\Delta F
\end{align*}

1. Define climate sensitivity

1. Given a forcing and a sensitivity, calculate a global temperature
change

$\Delta T = \lambda \Delta F$ (for equilibrium)

# Day 12: Forcings and Feedbacks

1. Understand the relationship between climate sensitivity λ and
equilibrium adjustment time constant τ.

1. Extend stock and flow model to include time-dependent energy storage in
the oceans.

\begin{align*}
\rho_{ w } c_{ w } D \frac { d T } { d t } = \Delta F - \frac{\Delta T}{\lambda}
= \Delta F + \sum f_{ n } \Delta T
\end{align*}

1. Equations: Classify each major feedback in the climate system (Planck,
water vapour, lapse rate, ice-albedo, clouds…) as amplifying or
stabilizing and describe how each affects the TOA fluxes.

1. Break down individual feedbacks into components that can be estimated
using models and observations: the change in forcing due to greenhouse
gas changes, and greenhouse gas changes due to temperature change.

1. Identify the conditions that could lead to a runaway-feedback scenario

# Day 13: Paleotemperature I

1. Describe how physical or chemical processes indirectly record past
conditions and allow us to reconstruct past climates

1. Describe the basis for using stable isotopes as paleo-thermometers in
ice cores, and the caveats.

1. Use stable isotopes to estimate paleo-temperature in ice cores.

**In-class quiz 2**

# Day 14: Paleotemperature I continued

# Day 15: Paleotemperature II

1. Use combinations of proxies (oxygen isotopes in shells and pore waters,
Mg/Ca, biological assemblages) to estimate temperature and sea level/ice
volume

1. Compare global temperature to regional temperature change over time,
including equator-to-pole temperature gradients.

# Day 16: Milankovitch Cycles

1. Describe the three major components of Earth’s orbital variation
(eccentricity, obliquity, precession), in terms of: (a) changes in
orbital geometry, (b) timescale, (c) effects on the amount and
distribution of solar radiation received by Earth, (d) effects on
seasonal contrast in each hemisphere (north and south).

1. Formulate a hypothesis describing the best orbital configuration for
growing (or melting) a continental ice sheet.

1. Compare changes in insolation forcing to climate records

1. Describe how the ice-albedo feedback helps explain the mismatch between
the amplitude of insolation forcing and the climate response.

# Day 17: Greenhouse Variability – millions of years

1. Identify carbon cycle processes relevant to million year time scales:
volcanoes, silicate weathering, formation/weathering of carbon rich
rocks

1. Describe long term changes in atmospheric $CO)2$ in terms of
balances and imbalances of carbon flows

1. Apply the silicate weathering thermostat to scenarios from Earth’s
climate past.

# Day 18: Greenhouse Variability – hundreds of thousands of years

1. Identify carbon cycle processes relevant to glacial - interglacial time
scales

1. Describe the two main pathways by which $CO)2$ gets from the
atmosphere to the deep ocean (solubility pump and biological pump)

1. Describe the factors that influence δ¹³C measured in shells

1. Compare and explain δ ¹³C data measured in shells during
glacial versus interglacial times

1. Explain how feedbacks between $CO)2$ and temperature can amplify
glacial-interglacial climate cycles

1. Describe the basis for using carbon isotopes to track carbon stocks in
the deep ocean

**In-class quiz 3**

# Day 19: Greenhouse Variability – century to seasonal

1. Identify carbon cycle processes relevant on century to seasonal time
scales. Describe the effects of these processes on atmospheric
composition (e.g. CO2, O2, δ¹³C)

1. Use the carbonate buffering system to explain what happens when the
oceans take up CO2 including effects on ocean pH.

1. Compare the amplitude of changes in atmospheric $CO)2$ that
occur on times scales from millions of years to seasonal

# Day 20: Paleo Analogues

1. Describe the geological evidence for rapid climate change during the PETM, and the timescale of recovery afterward.

1. Compare possible sources of CO2 to the atmosphere during the PETM using (1) carbon isotope data, (2) estimates of how much carbon would be required, (3) independent estimates of atmospheric CO2, (4) estimates of carbonate dissolution, (5) climate sensitivity

1. Evaluate the use of the PETM as an analogue for today’s anthropogenic carbon release and future global climate changes.

# Day 21: How do we know it’s us?

1. Use carbon isotope data to identify sources of carbon to the atmosphere

1. Compare stocks of atmospheric $CO_2$ to historical records of
human activities to estimate the fraction of $CO_2$ that remains
in the atmosphere each year

1. Interpret carbon isotopes, atmospheric O₂, historical human
records and models to evaluate the role of human activity in recent
climate change.

# Day 22: Climate Modelling

1. Explore how the Kaya Identity is used to estimate emissions.

1. Understand the relationship between climate sensitivity λ and
equilibrium adjustment time constant τ. (Day 12 review)

1. Relate the tiem evolution of temperature in Dessler Figure 8.3 to the simple
stock and flow with feedback model from Days 10-12.

1. Understand how climate models are built and used to make predictions for
various emission scenarios (RCPs and the Kaya relation).

1. Use stock and flow equations for abrupt and time dependent forcing to
relate temperature change, climate sensitivity, response time, mixed
layer depth. (From Day 12)

1. Understand how the stock and flow model is modified to include forcing
that changes due to changes in greenhouse gasses, solar insolation and
aerosols.

# Day 23: Climate Forecasts

1. Review current measurements of sea-level rise, temperature trends

1. Look at how both simple and complex models are used to predict climate
given emissions scenarios.

1. Make climate predictions given “business as usual” (RCP8.5)

**In-class quiz 4**

# Day 24: Future Decisions for Humanity

1. Estimate how long can we expect anthropogenic CO2 to remain in the
atmosphere given our understanding of long to short term carbon cycle
processes

1. Estimate time remaining to burn fossil fuels based on carbon budgets and
emissions pathways.

1. Evaluate future pathways humans might choose.

# Day 25: Final review