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What’s Up with the Atmosphere: Understanding
Our Weather & Changing Climate.
Course Structure:
Lecture, movies, discussion
Structured to be inclusive, scientists and non-scientists
First of all,
We live on an amazing planet.
 We live on a complex planet with a
multitude of interactions.
 One way that we understand this
incredible, yet complex world is
through science.
A. Chapter Overview
B. Science
1. Overview
B. Science – Overview
a. Science provides an effective, tested method
which allows us to understand our world.
b. All science is based on the idea that the natural
world behaves in a consistent and predictable
manner and always has (Uniformitarianism).
B. Science – Overview
c. We gain our fundamental understandings by
observing the natural world (Observations).
d. When there are two competing explanations, we
choose the simpler explanation (Parsimony).
e. Science is transparent, nothing is hidden. It is
important for scientific tests to be repeatable
(Repeatability).
B. Science – Overview
f. Science is a cumulative process, builds on
previous work.
g. Once science understands the functioning of
something, that understanding can be used to
model how things will change in the future or
how things will change under different scenarios.
1. Overview
2. The Scientific Method
a. You have a question
(What is happening to the world’s climate?)
b. You make relevant Observations
(air temperature, rainfall, cloud cover, etc.)
c. You analyze the observations and come up
with some conclusions (hypothesis)
d. You (or someone else) test your conclusions
(hypothesis) and if they pass the tests –
e. the hypothesis is considered a theory. It is
considered the most plausible scientific answer.
Based on Observations
One of my favorite story about the
scientific method concerns the
work of Dr. Jerry Stanhill.
 He was a British immigrant to Israel in the
1950s and worked on agricultural issues. In
the 1950’s he measured solar radiation to
determine how much water was needed for
irrigation.
 In the 1990s he re-measured solar radiation
and discovered that it had decreased some
22% since the 1950’s.
 Published work – little noticed, scientists
were skeptical.
Science is transparent – it is based on
repeatable observations and methods.
Science is meant to be skeptical. Where is
the data? What methods were used? Etc.
It is not a belief system, it is not something
you believe in or not believe in.
B. Science
The skeptical scientist
The baloney Detection Kit
https://www.youtube.com/watch?v=eUB4j0n2UDU
Weather & Climate
1. Weather
a. Weather: The daily conditions of the
atmosphere in terms of temperature,
atmospheric pressure, wind, and moisture.
The short-term state of the atmosphere at a
given location.
b. It’s with us every day
c. Usually unremarkable
d. Sometimes terrible - Hurricane Katrina.
C. Weather & Climate
1. Weather
e. Weather is now somewhat predictable because of
our understanding of the atmosphere and how it
functions.
f. Weather is essentially the movement of heat
around the Earth. For example – energy moving
from the tropics to the Poles.
Weather can be highly variable
2. Climate
a. Climate is the long-term average weather
pattern in a particular region.
b. Climate is described by many weather
elements such as temperature, precipitation,
humidity, sunshine, etc.
c. Both weather & climate result from processes
that accumulate and move heat within and
between the atmosphere and the earth, primarily
the oceans
d. Weather & climate are often confused.
Climate is average (typical) weather for a specific
place on earth based on multiple years of
observations (data).
The Earth’s Four Spheres
Earth as a System
a. Energy from the Sun runs the system
b. Chemicals cycle on Earth
c. Many Cycles, Ex: Tectonic Rock Cycle
d. Systems are linked /interconnected
e. Not just Natural: Human Activity also!
Causes of Weather
- Physical Properties of Earth
- Earth's Various Motions
- Solar Energy
Composition of the Atmosphere
1. Principal Components (by volume)
(Nitrogen 78%, Oxygen 20.9%, Argon
0.9%)
2. Minor Components (by volume) <0.2%
(Carbon Dioxide, Water Vapor,
Aerosols, Ozone, others)
The Changing Atmosphere
- Origin
- Change Through Time
- Modern Changes
Vertical Structure of the Atmosphere
http://www.dailymotion.com/video/x1cxgq7_earththe-power-of-the-planet-2-of-5-atmosphere_tv
Atmosphere
How about last February – cold,
cold and snowy.
Did that mean that the world is not
getting warmer?
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
Weather has considerable variation.
How can we determine natural
variation and change?
Weather has considerable variation.
How can we determine natural variation
and change?
Measure key components of weather
(temperature, precipitation) over long
periods of time and see if there are
patterns of change and if the change it
outside the normal variation.
D. Is Our Climate Changing?
1. Our Changing Climate
a. Over the past 100 years global
temperatures have been rising at a rate
slow relative to a human lifetime, but
quickly based on geologic time.
Graph of Temperature Anomalies
D. Is Our Climate Changing?
1. Our Changing Climate
b. With rising temperatures there has been
an increase in maximum temperatures,
heat waves, a decrease in minimum
temperatures, and a decrease in extended
cold waves.
D. Is Our Climate Changing?
1. Our Changing Climate
c. With rising temperatures there has been
an increase in droughts and severe weather.
d. In future chapters we will go over in detail
the changes occurring which are being
driven by a warmer world.
D. Is Our Climate Changing?
1. Our Changing Climate
So, we can look back in time.
Climate scientists have created a detailed
historical temperature record based on a
variety of techniques, such as through ice
core samples, sediment samples and tree
ring analysis.
D. Is Our Climate Changing?
1. Our Changing Climate
2. Climate Stability
How stable is our climate?
a. Climate scientists have created a detailed
historical temperature record based on a
variety of techniques known as climate
proxies, such as through ice core samples,
sediment samples and tree ring analysis.
2. Climate Stability: How stable is our climate?
b. This record indicates that the global
average temperatures have remained fairly
stable over the past 10,000 years since the
end of the last glacial period.
c. Following a post-glacial temperature
maximum of about 8,000 years ago, a slow
global cooling trend developed that lasted
until the end of the 19th century.
2. Climate Stability
However, long-term (hundreds of thousands of
years) climate has varied.
D. Is Our Climate Changing?
1. Our Changing Climate
2. Climate Stability
3. Historical Climate Change
3. Historical Climate Change
a. Climate change is natural and normal.
b. Past changes in climate are now well
documented. Through climate proxies, such as
ice cores and sediment samples, we are now
getting a clearer picture of past climate changes.
Through these proxies we are reconstructing a
temperature profile of the past.
c. Later in the semester we will look at some of
the past periods of climate change.
D. Is Our Climate Changing?
1. Our Changing Climate
2. Climate Stability
3. Historical Climate Change
4. Recent Climate Change
4. Recent Climate Change
The human impact on global temperature
change emerged from climate data around the
middle of the 20th Century soon after WWII. This
was a period of unprecedented industrial
expansion and massive economic growth.
In the 1970’s scientists warned society that the
excessive use of fossil fuels will heat the
atmosphere due to CO2. In the 1980’s they
discovered that this was true and continued to
warn – it was not until the 1990’s that society and
the government started to listen..
D. Is Our Climate Changing?
1. Our Changing Climate
2. Climate Stability
3. Historical Climate Change
4. Recent Climate Change
5. Temperature Observations
5. Temperature Observations
a. Temperature Records
Temperature is probably the best measurement to
make to monitor climate – it is a key indicator.
Although there is one location in central England
which has recorded temperatures back to 1659,
reliable regional data goes back to the 1850’s and
patchy global recordings go back to the late 1880’s.
True global coverage goes back to the 1970s with
the advent of satellite imaging.
5. Temperature Observations
a. Temperature Records
b. Recent Observations on Land
In 2005, average land surface temperatures have
exceeded 10 C (1.8 F) above the 1901-2000 annual
average. This is a significant increase because it
includes the entire land surface of the earth. In
addition, because we have not reduced our
greenhouse gas production the land surface
temperatures will continue to rise.
5. Temperature Observations
a. Temperature Records
c. Recent Observations in the Oceans
The world’s oceans have absorbed over 90% of the
excess heat produced by global warming and we
have measured increases in the oceans temperature
in the upper 700 meters (approximately 3,000 feet)
of the ocean. The average water temperature is now
0.490C (from book) warmer than the 20th century
average. Because the oceans are so vast, this
increase in heat means that a tremendous amount
of heat is being stored in the oceans.
D. Is Our Climate Changing?
1. Our Changing Climate
2. Climate Stability
3. Historical Climate Change
4. Recent Climate Change
5. Temperature Observations
6. A Century of Warming
6. A Century of Warming
As noted earlier, the Earth’s temperature has been
increasing over the past century. When looking at
the changes at the annual average level we see
variations form year to year where some years are
colder and some are warmer. This is because the
earth system is very complex and so it does not
warm in a linear fashion.
Graph of Temperature Anomalies
2014 – hottest year on record
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
E. Lessons from the Deep Past
E. Lessons from the Deep Past
1. Hothouse World / Icehouse World
E. Lessons from the Deep Past
1. Hothouse World / Icehouse World
The geologic record shows that the earth’s
climate has changed in a broad cyclical
pattern, going from hot conditions to cold
conditions.
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
E. Lessons from the Deep Past
F. Major Factors that Affect
Climate Change
Temperature is perhaps the most important
measurement in understanding weather &
climate.
The two most important drivers of
temperature on Earth is the difference
between the amount of:
1) Incoming solar radiation and
2) Outgoing terrestrial (Earth) radiation
F. Major Factors that Affect Climate Change
Many natural factors contribute to climate
change and we will be going into detail about
these factors later in the course.
F. Major Factors that Affect Climate Change
1. Radiative Forcing
a. Radiative Forcing - refers to an imbalance
that develops at the top of the atmosphere
between the incoming radiation (energy from
the Sun) and the outgoing radiation (heat) form
the Earth. This balance can be measured by
satellites in space.
F. Major Factors that Affect Climate Change
2. Incoming Solar Radiation
a. The Sun - The Sun is by far the most
important factor that controls radiative forcing.
b. Solar Radiation – short wave radiation
c. Earth-Sun Relationship
Rotation
Revolution
F. Major Factors that Affect Climate Change
d. Albedo - Albedo refers to the reflectivity of
the Earth – the more reflective the Earth is, the
less energy enters the Earth’s system.
i. Surface Albedo
ii. Atmospheric Albedo
F. Major Factors that Affect Climate Change
1. Radiative Forcing
2. Incoming Solar Radiation
3. Earth Radiation
The solar energy that does not get reflected out of the Earth
System (either by the atmosphere or the land) heats the
Earth. The Earth then loses energy to space through radiation
(Terrestrial Radiation).
F. Major Factors that Affect Climate Change
1. Radiative Forcing
2. Incoming Solar Radiation
3. Earth Radiation
4. Radiative Feedbacks
The balance between incoming and outgoing energy is determined
by a variety of energy drivers (such as solar output) and is mediated
by a complex set of interactions referred to as feedbacks.
a. Positive Feedback - amplifies change and
moves it away from equilibrium.
b. Negative Feedback - minimizes change,
brings change back to equilibrium.
F. Major Factors that Affect Climate Change
1. Radiative Forcing
2. Incoming Solar Radiation
3. Earth Radiation
4. Radiative Feedbacks
5. Timescales of Climate Change
There are a number of broad factors that change the balance,
some function on short-time scales and others on long time
scales (thousands to millions of years).
a. Solar Cycles – The energy output from
the Sun is not constant, it varies over time and
this causes variations in the Earth’s climate.
5. Timescales of Climate Change
a. Solar Energy – The energy output from
the Sun is not constant, it varies over time and
this causes variations in the Earth’s climate.
There are solar cycles, a fairly consistent cycle
is the 11-year sunspot cycle. Increases in
sunspots = increase in solar energy output.
5. Timescales of Climate Change
b. Global Tectonics – On a timescale of
millions of years the contents on the surface of
the Earth move to new locations creating new
climates for those landmasses.
c. Earth’s Orbit – the orbit of the earth
varies over the scale of tens to hundreds of
thousands of years. As the orbit changes the
amount of solar radiation reaching the earth
changes and this changes the climate.
5. Timescales of Climate Change
d. The Oceans – On a scale of hundreds
of years the oceans move heat deep into the
ocean and then to the surface.
e. Ocean – Atmosphere Interaction
On a timescale of years to decades, the oceans
and the atmosphere exchange heat and
greenhouse gases.
5. Timescales of Climate Change
f. Volcanic activity – There is intermittent
activity with volcanoes.
Do volcanoes heat or cool the atmosphere?
5. Timescales of Climate Change
6. Greenhouse Gases
Finally, one of the major influences on our
global temperatures are greenhouse gasses
which keep the Earth’s heat from escaping to
space. Much more on this later in the semester.
6. Greenhouse Gases
7. Recent Radiative Forcing
Because most of the natural factors that drive
climate change are long-term slow processes, and
because none of the short-term factors have been
detected; there is no evidence that natural
climate change can explain the significant change
in the global temperature rise since the mid-20th
century.
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
E. Lessons from the Deep Past
F. Major Factors that Affect Climate Change
G. Climate Models
G. Climate Models
1. Introduction
One key aspect of science is that once we
understand how things function – we can
predict how they will function in the future.
Based on our understanding of how the
climate functions, we are able to model how
it will change in the future given different
situations (changes in solar radiation,
changes in amount of solar radiation, etc.
G. Climate Models
1. Introduction
a. Global Circulation Models (GCMs)
GCMs attempt to make order out of the climate
complexity. CGMs are computer models which tries
to reproduce the influence that a number of
climate-regulating processes exert on climate
variability.
Global Circulation Models (GCMs)
2. Model Operations
a. Spatial Resolution
The resolution of the model determines if it’s
predictions are for an area the size of continental
US or New England. The model is made up of grids
and is known as a RASTER-based system.
b. Vertical Dimension
Not only is there a cell size on the horizontal place
there is a vertical dimension because atmospheric
processes change as you move vertical above the
Earth’s surface.
Global Circulation Models (GCMs)
c. Temporal Resolution
Models also need to update the data on a time
scale to try and mimic what happens on earth as
the weather changes hour from hour. A typical time
from is refreshing the data every 6 hours.
d. Issues
Some processes occur in an area smaller than the
associated cells (such as some types of cloud
formation) so estimates must be made for these
processes which occur at a smaller size.
Global Circulation Models (GCMs)
e. Dealing with Uncertainty
1. Internal Uncertainty
2. Model Uncertainty
3. Scenario Uncertainty
Global Circulation Models (GCMs)
f. Model Operations
When a model starts, it begins with a set of initial
conditions for the atmosphere, oceans, etc. Then it
begins to calculate how things will change as new
data are added to the model in time sequences
(temporal resolution). Because weather is so complex
and it is hard to know every cause and effect,
multiple model runs are done with slight variations
to try and identify a variety of possible outcomes and
the most probable outcome.
Global Circulation Models (GCMs)
f. Model Operations.
Ensemble - a collection of model runs.
Because weather is so complex and it is hard to
know every cause and effect, multiple model runs
are done with slight variations to try and identify a
variety of possible outcomes and the most
probable outcome.
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
E. Lessons from the Deep Past
F. Major Factors that Affect Climate Change
G. Climate Models
H. Economic Projections
H. Economic Projections
Climate models depend on accurate projections of
future greenhouse gas emissions, and these in turn
depend on economic forecasts, future population
growth, technological development and
governmental and societal action.
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
E. Lessons from the Deep Past
F. Major Factors that Affect Climate Change
G. Climate Models
H. Economic Projections
I Use of Climate Models
Global Circulation Models (GCMs)
f. Use of Climate Models
Climate models have been tested where change is
predicted using various inputs and then the results
are check with what actually happened. This type
of verification has shown that climate models have
become better predictors of potential future climate
change and scientists have more confidence in
these models and they are showing the world that
there are some potential major changes occurring
in the future if we don’t change our current
production of Greenhouse Gases.
A. Chapter Overview
B. Science
C. Weather & Climate
D. Is Our Climate Changing?
E. Lessons from the Deep Past
F. Major Factors that Affect Climate Change
G. Climate Models
H. Economic Projections
I Use of Climate Models
J. The Next Decade
J. The Next Decade
There will be a continued warming of the air,
land and water as well as the melting of the
cryosphere. Over the next decade the pace of
global warming and climate change will
accelerate.
End of Chapter 1