The Physics and
History of Climate
Dan Britt
University of Central Florida
PSC 1121
• This course is an introduction to the
fundamental laws of physics using the
history and dynamics of the Earth’s climate
as our example and unifying theme
• We will use physics to understand the nuts and
bolts of how the climate works
• How we know about past climates
• How we can understand the changes
• Textbook
• Visualizing Weathering and Climate, by Bruce
Anderson and Alan Strahler.
• Extra readings in pdf
Class Mechanics
• 3 Exams:
– all equal weight, 80% of grade
– 2 in-class exams as listed in the schedule
– A final which will be comprehensive
• Quizzes:
– I will give short in-class quizzes once or twice a
week using a red half-sheet. Bring one to class!
– There will be up to 20 quizzes. I will count 18, so you
can miss 2 for free.
– Quizzes will count 20% of the overall grade.
• Make-up work
– Only permitted for University-sanctioned activities
and bona fide medical or family reasons.
Class Mechanics
• Extra Credit
– Write a 5-page (single spaced) research paper on
a climate science topic
– I will provide a list of topics
– Worth up to 4% extra credit
• Your Professor
– Office is Physical Sciences 442
– Office hours are M-W 1:30-2:30 or by appointment
– Scheduling issues…..
Lectures
• I am not here to read you the book
– I am what is called an “expert”
– There are lots of important things that I think you
NEED TO KNOW are NOT in the book….they will be
in the lectures
• I will post the powerpoints I use
– http://physics.ucf.edu/~britt/Climate/
– BUT….This is NOT an on-line class
– Almost every class will have a section that is NOT in
the Book and will NOT be put in the on-line
powerpoints….but will be on the tests.
– There is no substitute for coming to class
How to Get an “A”
• ALL of you can get A’s in this class…..I have
tenure.
• How to do it #1: Attend class!
– People who blow off the lectures don’t do very
well….figure 30% of test questions will NOT be
from the book or posted slides
– Sit in the front….
• #2: Read the book!
– Quizzes will tend to be on book material in
advance of the lectures
• #3: DO the extra credit!
– That will usually up you a grade level
Dr. Britt’s quirks
• I ask questions…..
– Correct answers get extra points.
– I prowl around the class to ask questions.
– I will always ask a couple of questions of
those in the back row.
– If you are shy, sit in the front row.
• I invite you to ask questions.
– You do get points for good questions….
Why am I Teaching this subject?
• My “day job” is Astronomy
– Background in Planetary Geology.
– My work is on the geology of asteroids and
comets.
• I did climate work
early in my career.
• I was involved in
taking some of the
data that will be
presented in this
course
– б18O from ice cores
– б18O from Corals
• I also worked with
some of the
founders paleoclimatology
You Hear a Lot about Climate…..
•
•
•
•
•
•
•
Greenhouse gasses are warming the globe
Sunspots cause warming
We are in an Ice Age
Glaciers are melting
Glaciers are advancing
Sea level is rising
CO2 is natural
– CO2 is a lot higher now than in the past
– CO2 is a lot lower now than in the past
• The Earth was a lot warmer in the past
• The Earth was a lot colder in the past
You Hear a Lot about Climate…..
•
•
•
•
•
•
•
Greenhouse gasses are warming the globe
Sunspots cause warming
We are in an Ice Age
Glaciers are melting
Glaciers are advancing
Sea level is rising
CO2 is natural
– CO2 is a lot higher now than in the past
– CO2 is a lot lower now than in the past
• The Earth was a lot warmer in the past
• The Earth was a lot colder in the past
And everything here is true…..
What is "Normal" for the
Earth?
Is today's climate
NORMAL for the
Earth?
Weather and Climate
• Weather is a set of all the phenomena
occurring in a given atmosphere at a given
time.
– Weather occurs due to density (temperature and
moisture) differences between one place to
another.
• Climate encompasses the meteorological
factors in a given region over long periods of
time
Cold snaps of
times past
• The first Thames frost fair
was in 1607; the last in
1814.
• In the 1600’s ice racing
became a national sport in
Holland.
– The major race was thru
nine cities along the canals
– It was last held in the 1960’s
• Winter of 1780, New York
Harbor froze, allowing
people to walk from
Manhattan to Staten
Island.
What is Normal?
What is Normal for Sea Level?
What is Normal?
What is Normal?
Venus
Earth
Earth w/o
Life
Carbon Dioxide
98%
0.03%
98%
Nitrogen
1.9%
79%
1.9%
Oxygen
trace
21%
trace
Surface Temp
477ºC
13ºC
290 ºC
Atm. Pressure
(bars)
90
1.0
60
By 2.5 Billion years ago plankton were
altering the oxygen content of the atmosphere
Banded-Iron Formations
• Caused by the oxidization of iron
• Contain about 20 times the mass of
the current atmosphere in oxygen
• Where did the Carbon go?
• Is the current level of oxygen
normal?
Anything Special About 21% Oxygen?
Lets look at conditions during the
last hot period
Cretaceous: “abundance of chalk”
Climate in the Cretaceous
Evidence
• Warm-adapted vegetation
and critters north of the
Arctic circle
– Brown-leaf evergreens
– Turtles and crocodiles
• No continental glaciation
• Tropical conditions to 40
– Coral growing at the
paleolatitude of New York
– NO HARD Freezes in
temperate latitudes.
• Pretty nice, but there is
a down side…..
Sea Level was up to 200 meters
HIGHER!
Why so much warmer?
• CO2
– at ~1700 ppm… about 6
times pre-industrial
levels
• Geography
– Continents closer to the
equator
• Ocean Circulation
– Today the atmosphere
transports about double
the heat that the oceans
transport
– In Cretaceous that ratio
was probably reversed
FYI: Toxicity of CO2
• Current atmosphere level is ~400 ppm
• OSHA says that average exposure for
healthy adults during an eight-hour work
day should not exceed 5,000 ppm (0.5%).
• CO2 concentrations exceeding 4% are
immediately dangerous to life and health.
• Concentrations higher than 1,000 ppm will
cause discomfort in more than 20% of
occupants, and the discomfort will
increase with increasing CO2
concentration.
Since the Cretaceous….
• Over the past 2.7 million years the
Earth’s climate has cooled and
caused a series of glaciations.
NORMAL for the last 500,000
years is MUCH COLDER
18,000 years ago the world was a much different place
Go to Central Park, look for yourself
What is the Earth’s
NORMAL climate?
Is this NORMAL climate?
• There is NO “normal” climate
• On average Earth’s climate has been
MUCH warmer over the last 500 Myrs
• Average means:
‒ NO continental glaciation
‒ Sea level about 350 feet higher
‒ Temperate vegetation north of the arctic
circle
‒ Climate of the Keys as far north as Ohio