Transcript PPT - UW Atmospheric Sciences

ATMS 211
Climate and
Climate Change
Winter 2008
Prof. Thornton
T.A. Brian Smoliak
Times and Locations
Lectures M - Th: 10:30 – 11:20
JHN 075
Disc: F 10:30 – 11:20/11:30 – 12:20
MGH 389 (AA) MGH 241 (AB)
Who Am I?
Prof. in Dept. of Atmospheric Sciences
Ph.D. in Atmospheric Chemistry
Scientific Interests:
Natural and polluted air
chemistry
How pollution affects
climate
How climate change
affects pollution
Contact Info
1. After lecture
2. Office hours (TBD) or
special appointment
3. Message board (see web
page)
4. Email/Phone*
Course Goals
Introduce you to climate
science and the scientific
process
Give you tools to understand
and critically evaluate modern
environmental problems
What this course is/isn’t about
YES: Current scientific
theories and observations
about the workings of Earth’s
climate.
i.e. what, how, why?
NO: morals, philosophies,
politics, etc
Course Overview
The Climate System (Present)
•Earth’s Energy Balance
•Earth’s Atmosphere
•Regional Climates
Climate Changes (Past-Present)
•Change and Feedbacks
•The Human Influence
•Natural Variations
Global Warming (Future)
•Evidence
•What can we expect?
•Mitigation Approaches
Grading Policy
Exams and Project ~ 85%
•homework (15%): old exam problems
•clicker questions: worth ~ 1 exam!
Plagiarism/Working Together
•see UW policy on plagiarism
•discussions are encouraged
•on your own for exams
Grading Method
•mean 2.8 – 3.2 (B- to B)
NO LATE HOMEWORKS
NO MAKEUP EXAMS or QUIZZES*
Course Guidelines and Philosophy
UW Credit Hours
•2hrs outside per credit hr
Lectures/Discussion
•FOR YOUR BENEFIT!
•Stop me, ask questions!
•Comfortable Atmosphere
•Let me know immediately
How To Do Well
1. COME TO CLASS
2. TAKE GOOD NOTES
3. REVIEW YOUR NOTES
4. TEST YOURSELF
5. RELAX
GET YOUR QUESTIONS ANSWERED
MATH
Math is the language of the
natural sciences
You will see and learn to use
a number of equations
Think positively!
This course and your grades
are based on concepts (not
mathematical ability)
This Week: The climate system
Read Chapter 1
Due Friday (in section):
200 word synopsis of a recent
news article on climate change
200 word description of the
climate of an area you’ve lived
(ideally besides Seattle).
Discussion activities:
math and geography surveys,
what is/isn’t climate change?
Graphic Analysis Exercise
1.
What are the x-y pairs in
each plot (3 total)?
2. What are the units for
each axis (1 x, 3 y’s)?
3. Do you see correlations, or
lack thereof, where?
4. What do you find
interesting/important?
5. What do you find
misleading or confusing?
Summary of Graphic Analysis
Summary of Graphic Analysis
Summary of Graphic Analysis
These measurements were made
by examining air trapped in
an ice core drilled at Vostok
in Antarctica.
How do you measure past
Temperature in ice?
Is this just representative
of Antarctica’s climate?
Announcements
• Message board
• Extra credit opportunities
• Lecture visuals
Today – Defining the problems
• Climate vs. Weather
• Climate Change (a definition)
• Global Warming
– By way of “myths and misconceptions”
Myths and Misconceptions (1)
“Its 70o today, in January? Global
warming is real.”
“Hurricane Katrina was the strongest
hurricane in decades. Global warming
must be real.”
Weather vs. Climate
“Climate is what we expect.
Weather is what we get.”
– Mark Twain
What do we mean by climate change?
Long-term variation in an average property,
related to weather, that is significant compared
to natural variability, or an alteration in the
variability.
Recent climate change
15
13.2
Figure 3.1
From Intergovernmental Panel on Climate Change AR4 2007.
Weather Change vs. Climate Change
•A single hurricane is an
example of weather.
•An increase in the
number per year or
average strength is a
climate problem.
In the eye of Hurricane Katrina
Photo courtesy of Prof Bob Houze’s group
Myths and Misconceptions (2)
“The decrease in pirates anti-correlates with global
temperature. Thus, global warming is caused by
fewer pirates (or it is causing there to be fewer
pirates).”
Need to have a
physical explanation
for correlations to
be meaningful
Myths and Misconceptions (3)
“The recent warming is just part of a
natural cycle.”
IPCC—A good course resource
Intergovernmental Panel on
Climate Change
A consensus document of
the scientific community
“Most of the observed increase in
globally averaged temperatures
since the mid-20th century is very
likely (sic) due to the observed
increase in anthropogenic
greenhouse gas concentrations” -2007
Increasing CO2
Fig 1-2 from text. Known as “Keeling Curve”.
Increasing CO2
Fig 1-3 from text. Keeling Curve and Ice Core data.
Global Warming vs. Climate Change
UN Definition of Global Warming:
“A change of climate which is attributed directly
or indirectly to human activities that alter the
composition of the global atmosphere... “
Myths and Misconceptions (4)
“Is global warming really such a big deal? A
few degrees warmer seems harmless.”
Summary of Graphic Analysis
Tice-no ice
Seattle ice free
~ -5-8o
Seattle under
mile of ice
Observed Changes in T, Sea Level, Snow/ice
Figure SPM.3
Predictions of Changes to Come
4 – 6O C increase in global average T is predicted to bring:
1. A sea level rise of 0.5 – 1.5 feet (or more) by 2100
2. Wetter wet regions and drier dry regions
3. More frequent and more intense heat waves
4. Stressed drinking and irrigation water supplies (Mtn
glaciers)
5. Nearly all multi-year sea ice gone?
1 meter (3ft) sea level rise - world
1 meter (3ft) sea level rise - SEUS
arctic sea ice graphic
WHY?
• A goal of this course will be to understand
why we should expect such changes
– What are the connections between:
• Air T and precipitation patterns?
• Air T and storms?
• Air T and sea level/ice extent
Myths and Misconceptions (5)
“The Earth is too large/complex for humans
to cause significant environmental change.”
“The hole in the ozone layer is increasing,
causing global warming.”
Ozone
A molecule containing three oxygen atoms found
throughout the atmosphere.
Plays a role in climate, but the role is complex.
The “ozone hole” is NOT the cause of recent
warming.
Ozone “Hole”
Summary
• Climate: long-term (> 10 yrs!) average of the
weather
• Climate Change: long-term variation in an
average property related to weather or the
natural variability of that property
• Global Warming: human-induced climate change
Today – Environmental Change Concepts
• Determining whether change is significant
• Rates of change – Mass/Energy balance
• No change
Significant?
15
13.2
Figure 3.1
From Intergovernmental Panel on Climate Change AR4 2007.
Recent Changes are Significant
Figure SPM.4
CO2 Mixing Ratio (ppm) at Mauna Loa
CO2 Rate of Change
390
380
370
Monthly Mean CO2 Mixing Ratio
Annual (running) Mean CO2 Mixing Ratio
360
350
340
330
320
310
1950
1960
1970
1980
Year
1990
2000
2010
CO2 Mixing Ratio (ppm) at Mauna Loa
Change of CO2 Rate of Change
Rates are often
not constant in
time.
390
380
370
Monthly Mean CO2 Mixing Ratio
Annual (running) Mean CO2 Mixing Ratio
360
350
16 ppm
340
330
10 yr
320
310
1950
1960
1970
1980
Year
1990
2000
2010
Change in the CO2 Rate of Change
Rate of Change of CO
Mixing Ratio (ppm/yr)
2
CO2 is increasing faster and faster (on average!)
From Observations
Linear Fit to Observations
3
2
1
0
1960
1970
1980
Year
1990
2000
2010
Has the CO2 rate of change ever been
negative (<0), i.e. has CO2 decreased at
any time since 1955?
60%
390
380
370
40%
Monthly Mean CO2 Mixing Ratio
Annual (running) Mean CO2 Mixing Ratio
360
350
340
330
1950
1960
1970
1980
1990
2000
2010
N
s
310
o
320
Ye
CO2 Mixing Ratio (ppm) at Mauna Loa
1. Yes
2. No
Because the CO2 rate of change is constant at 1.6
ppm/yr, it will take 175 years to double the
preindustrial amount of atmospheric CO2 (280 ppm)
89%
1. Valid statement
2. Invalid statement
st
va
lid
In
Va
lid
st
at
em
at
em
en
en
t
t
11%
Summary
• Rate of change of Y is the slope of a
plot of Y vs time
• Rate < 0  quantity is decreasing,
Rate > 0  quantity is increasing,
Rate = 0  quantity in steady state
• Rates of change are often not constant
Announcements
• Two short assignments due tomorrow (FRI)
in discussion section.
• Lecture slides will appear on the course
web site weekly.
• Office hours determined Monday in class
by clicker vote
– Tu or Th 11:30 – 12:30 or 4 – 5 pm
– Brian (TA): M, Tu, W, or Th 9 – 10 AM
» And Tu or Th 5 – 6 pm
Today – Environmental Change Concepts
• Rates of Change – what they tell us
– Concepts of Mass and Energy Balance
– Residence time
• Measuring Change in the Past
Change in the CO2 Rate of Change
Rate of Change of CO
Mixing Ratio (ppm/yr)
2
CO2 is increasing faster and faster (on average!)
From Observations
Linear Fit to Observations
3
2
1
0
1960
1970
1980
Year
1990
2000
2010
Summary from Yesterday
• Rate of change of Y is the slope of a
plot of Y vs time
• Rate < 0  quantity is decreasing,
Rate > 0  quantity is increasing,
Rate = 0  quantity in steady state
• Rates of change are often not constant
Unlocking “Stored” Climate Change
• Modern Instrumental Record
• Tree Rings
• Ice Cores
• Sediment cores
• Rock formations/types
Record: 1000 ~ Present day
“Length” of growing season
Good versus stressed years
Major fires
Unlocking “Stored” Climate Change
• Modern Instrumental Record
• Tree Rings
• Ice Cores
• Sediment cores
• Rock formations/types
Record: ~ 1Mya to ~ 20th cent
Inert gases (CO2, CH4, N2O,…)
Particulates (soot, ash, etc)
Temperature??
Unlocking “Stored” Climate Change
• Modern Instrumental Record
• Tree Rings
• Ice Cores
• Sediment cores
• Rock formations/types
Record: ~ 200 Mya
Microfossils (ocean T),
Volcanic glass
Organic detritus
Magnetic pole location
Detecting Change With Proxies
Scientifically, the best way to detect change is to
directly measure it.
Unfortunately for the timescales of interest in climate
science, we weren’t always able (interested in?) to
measure quantities such as temperature, precipitation,
wind speed, direction, greenhouse gas levels, etc.
But, obviously we want to know what these properties
were and how they changed in the past to test our
understanding of how climate changes.
The study of past climate is known as paleoclimate
science.
Detecting Change With Proxies
Another property/qty that is a function of
property of interest.
Think approximate
The measured property is a PROXY for the one of interest.
Water Cycle – Water Isotope T Proxy
18O/16O
18O/16O
18O/16O
high
low
lower
18O/16O
lower
even
Vostok Ice Core Record
T based on water
isotope proxy
Stratospheric Ozone “Hole”
Course Format
Course Web Site
•Consult often (weekly schedule,
problem sets, lecture material)
Course Discussion Board
•Remain anonymous (or not)
•Your post
•TA and Prof monitor/respond
Mon-Thurs
•lectures, in-class activities and
quizzes (Prof)
Fridays
•discussions, reviews, working
examples, quizzes & exams (TA)
Global Climate Change?
Time scales
Spatial Scales