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Climate Change: General Introduction
(Basic Introduction for Students with
Some Science Knowledge)
Richard B. Rood
Cell: 301-526-8572
2525 Space Research Building (North Campus)
[email protected]
http://aoss.engin.umich.edu/people/rbrood
February 4, 2015
Some Basic References
• Intergovernmental Panel on Climate Change
– IPCC (2007) Working Group 1: Summary for Policy Makers
– IPCC (2013) Working Group 1: Summary for Policy Makers
• Spencer Weart: The Discovery of Global Warming
• Carbon dioxide greenhouse effect:
http://www.aip.org/history/climate/co2.htm
• Simple climate models
http://www.aip.org/history/climate/simple.htm
• Paul Edwards: A Vast Machine
• Rood
– Rood Climate Change Class
• Reference list from course
– Rood Blog Data Base
Naomi Oreskes, Why Global Warming Scientists are Not Wrong
Climate Change in a Nutshell
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How and what do we know?
Increase of carbon dioxide
Some predictions
Some observations (and attribution)
How do we organize our responses?
Reading about 4 degrees of warming
– New et al. 2010, Phil. Trans. Roy. Soc.
Starting point: Scientific foundation
• The scientific foundation of our
understanding of the Earth’s climate is
based on budgets of energy, mass, and
momentum. (Conservation principles)
• The scientific foundation of our
understanding of the Earth’s climate is
based on an enormous and diverse
number of observations.
Starting point: A fundamental conclusion
• Based on the scientific foundation of our
understanding of the Earth’s climate, we
observe that with virtual certainty
– The average global temperature of the
Earth’s surface has increased due to the
human-caused addition of gases into the
atmosphere that hold heat close to the
surface.
Starting point: A fundamental conclusion
• Based on the scientific foundation of our
understanding of the Earth’s climate, we predict
with virtual certainty
– The average global temperature of the Earth’s
surface will continue to rise because of the continued
increase of human-caused addition into the
atmosphere of gases that hold heat close to the
surface.
– Historically stable masses of ice on land will melt.
– Sea level will rise.
– The weather will change.
Scientific Approach
• Climate science is observationally based
• Climate change is computational science
– Relies on models
Models are an Important Part of Climate Science
What is a Model?
• Model
– A work or construction used in testing or perfecting a
final product.
– A schematic description of a system, theory, or
phenomenon that accounts for its known or inferred
properties and may be used for further studies of its
characteristics.
• Numerical Experimentation
– Given what we know, can we predict what will
happen, and verify that what we predicted would
happen, happened?
Scientific Investigation
OBSERVATIONS
THEORY
PREDICTION
Past
Present
Future
Time
Understanding Processes
Evaluation, Verification
Predictions
Projections
Summary Points: Science
Correlated Observations
CO2 and Temperature Observed to be
strongly related on long time scales (>
100 years)
CO2 and Temperature not Observed to be
strongly related on short time scales (<
10 years)
Land Use / Land Change
Other Greenhouse Gases
Aerosols
Internal Variability
Theory / Empirical Evidence
CO2 and Water Vapor Hold Heat Near
Surface
Theory / Conservation Principle
Mass and Energy Budgets
 Concept of “Forcing”
Prediction
Earth Will
Warm
Validation
Evaluation
Consequences
Observations
CO2 is Increasing due to Burning Fossil
Fuels
Feedbacks
Air Quality
“Abrupt” Climate Change
Conservation principle: Energy
Energy from the Sun
Stable Temperature of
Earth could change
from how much
energy (production)
comes from the sun,
or by changing how
we emit energy.
Earth at a certain
temperature, T
Energy emitted by Earth
(proportional to T)
The first place that we apply the conservation
principle is energy
• We reach a new equilibrium
T
 0  H - T
t
Production  Loss
H
T

The first place that we apply the conservation
principle is energy
• We reach a new equilibrium
T
 0  H - T
t
Production  Loss
H
T

Changes in orbit or solar
energy changes this
Conservation principle: Energy
Energy from the Sun
Add some detail:
Earth at a certain
temperature, T
Insulating Blanket
Surface
The first place that we apply the conservation
principle is energy
• We reach a new equilibrium
T
 0  H - T
t
Production  Loss
H
Changing a greenhouse gas
T
changes this

Some basics
Observed Increase of Atmospheric Carbon Dioxide (CO2)
Primary
increase comes
from burning
fossil fuels –
coal, oil,
natural gas
Data and more information
The yearly cycle
of CO2
Presentation of some results
• These are drawn from the Reports of the
Intergovernmental Panel on Climate
Change. I deliberately mix graphs from
reports in 2001, 2007, and 2013. The
messages from these reports are quite
similar, which is a measure of
– Consistent measure
– Stable scientific understanding
IPCC (2007) projections for the next 100 years.
Projected Global Temperature Trends: 2100
2071-2100 temperatures relative to 1961-1990.
Special Report on Emissions Scenarios Storyline B2 (middle of the road warming).
IPCC 2001
Observed Temperature Anomaly in 2005
http://data.giss.nasa.gov/gistemp/2005/
See Also: Osborn et al., The Spatial Extent of 20th-Century Warmth in the Context of the
Past 1200 Years, Science, 311, 841-844, 2006
IPCC 2013: Observed Temperature
What does this mean for design and engineering?
Rood: What would happen if we stopped emitting now?
IPCC 2007:
The last
~100 years
Correlated behavior of different parameters
Fig. 2.5. (State of Climate 2009) Time
series from a range of indicators that
would be expected to correlate
strongly with the surface record.
Note that stratospheric cooling is an
expected consequence of greenhouse
gas increases. A version of this figure
with full references is available at
www.ncdc.noaa.gov/bams-state-of-climate/ .
Quick Summary: IPCC(2013)
Length of
Growing Season
From Ranga B. Myneni, Boston University
Summary In Progress: Observations
• Observations of climate change (global
warming)
– Average surface temperature of planet is
increasing
– Ice is melting
• Glaciers
• Ice sheets
– Sea level is rising
• Ocean is warming up
• From the melting ice
– Weather is changing
• Coherent and convergent evidence
Summary In Progress: Projections
• Observations are consistent model
projections
– Past century
– Evolving
• Model projections
– Planet will warm
– Ice will melt
– Sea level will rise
– Weather will change
Summary In Progress: Uncertainty
• Identified major categories of uncertainty
– Scenario – future emissions
– Model – deficiencies in simulation capability
– Observational – quality of observations,
inability to completely observe
– Dynamic variability – internal variability due to
transfer of energy between components of a
complex system
Summary in Progress: Attribution
• Have suggested several aspects of extent
and attribution of warming to greenhouse
gases
– Spatial distribution of warming
– Decrease of temperature in the stratosphere
– Changes in growing season
– Changes in seasonal cycle of carbon dioxide
– Warming in the ocean
– ….
What parameters/events do we care about?
• Temperature
• Water
– Precipitation
– Evaporation
– Humidity
• Droughts
• Floods
• Extreme Weather
• Air Composition
– Air quality
– Aerosols
– Carbon dioxide
• Winds
• Clouds / Sunlight
The impact of climate change is
Water for Ecosystems
Water for People
Water for Energy
Water for Physical Climate
Science, Mitigation, Adaptation Framework
It’s not an either / or argument.
Adaptation is responding to changes that might occur from added CO2
Mitigation is controlling the amount of CO2 we put in the atmosphere.
Stabilization / Total burden of Greenhouse Gases
• Have this notion of controlling emissions to stabilize the
concentration of CO2 in the atmosphere at some value.
– That is, there was some value of emissions that would match the
loss of CO2 into the plants, soil and oceans.
– However, CO2 is exchanged between these reservoirs, and it
takes a very long time for CO2 amounts to decline.
• We know that the CO2 that we emit will be with us
essentially forever. Therefore, it is the total amount that
we emit, rather than controlling emissions.
– Arguably, we get to emit 1 trillion tons before climate change is
“dangerous”
– “Dangerous” = 2 degrees C average surface warming
Some Points
• Science-based conclusions
– The surface of the Earth has warmed and this
warming is consistent with increasing
greenhouse gases. CO2 is most important.
– The Earth will continue to warm.
– The concept of “stabilization” of CO2 is
challenged by the consideration of oceanland-atmosphere time scales
• Accumulated carbon dioxide is important.
• 1 trillion tons  440 ppm
Some Points
• Analysis and Opinion
– Probability of stabilizing at less than 440, 560 … ppm
is very small.
• If we decide to stabilize at 350, 440, then we need
to figure out how to remove CO2 from the
atmosphere.
Some Points
• Analysis and Opinion
– We need to start to plan for a world that is on
average, warmer than the 2 degrees C that we have
deemed as the threshold of “dangerous”.
– We have an enormous opportunity provided by
predictions of climate change. We have the choice of
whether or not to take advantage of this opportunity
on personal, professional, local, national, and
international levels.
• The world 4 degrees warmer: January 13, 2011 issue of The
Philosophical Transactions of the Royal Society
Some Other References for the Interested
• Rood
– Rood Blog “Just Temperature”
– Rood Blog: Arctic Oscillation and Cold Times in
Eastern North America
– Rood Blog: Trillion Tons of Carbon Dioxide
– Rood Blog: Warming Hiatus
• Lemos and Rood (2010)
• Koshland Science Museum: Global Warming