Transcript Earth System - cloudfront.net

A Self-Guided Tutorial
The Wicked Problem of Global Food Security
Introduction to the Climate System
1
Preparing for this Module
After completing the activities in this slide stack, you will be able to:
1. Describe in general terms how unequal heating of the planet creates
the patterns of air and ocean circulation, which in turn, are responsible
for Earth’s latitudinal climate zones.
2. Create a diagram that shows how changes in the flux and residence
time of carbon reservoirs are responsible for our warming climate.
3. Use an Earth system diagram to show how changes in the Earth
system challenges global food security.
2
Preparing for this Module
This slide set introduces how
climate zones are generated and
discusses how increasing the flux
of carbon into the atmosphere is
responsible for changing climate.
In this slide stack, there are four embedded
short assignments where you will:
•
•
•
•
Explore an interactive
Watch 2 short videos
Complete a reading assignment
Write a paragraph summary to bring to
class.
Using these resources and the information
in the slide stack, create a paragraph where
you summarize your understanding of the
Earth system, changing climate and
potential or observed impacts on the global
food system. You will bring this to class as
your homework assignment. Expect to
spend 1 hour on this homework activity
Image: GLOBE.gov
3
The
Earth
System
The
Earth
System
is aisClimate
System
a Climate
System
Its all about Interconnections!
•
The Earth system behaves as a
single, self-regulating closed
system comprising physical,
chemical, biological and human
components.
•
The focus of Earth system
science is understanding the
interactions between water, air,
life, geological processes and
the land surface, and how those
interactions impact each other
and lead to changes on our
planet.
•
These same ideas help us to
understand how Earth’s climate
is created.
Image: GLOBE.gov
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Unequal Heating Drives Air and
Ocean Circulation
Earth’s climate zones are the
result of the Sun’s energy being
unequally distributed on the
planet’s surface.
This is because as the angle at which the
sunlight strikes the Earth surface
increases, the amount of energy
transmitted per area decreases:
•
•
At 60 degrees latitude, energy per unit area
is 50% of the intensity at the equator
Low density, high angle incident rays=
less energy per square km
cooler
warmer
cooler
High density, low angle incident rays=
More energy per square km
Low density, high angle incident rays=
less energy per square km
At 30 degrees latitude, energy per unit area
is 87% of the intensity at the equator.
The unequal heating of the
Earth’s surface causes climate to
vary by latitude.
Image: Blue Marble from NASA Earth Observatory
5
Unequal Heating Drives Air and
Ocean Circulation
The unequal heating of the Earth’s
surface causes climate to vary by
latitude.
Air and water circulation is initiated
at the equator. Masses of air and
ocean transport heat energy from
areas of high concentration to low
concentration.
The movement of these masses of
air and ocean establish an
equilibrium state of heat distribution
which we determine the general
climate bands, or zones that we
see at different latitudes.
cooler
ocean
circulation
warmer
cooler
Low density, high angle incident rays=
less energy per square km
atmospheric
circulation
High density, low angle incident rays=
More energy per square km
Low density, high angle incident rays=
less energy per square km
Image: Blue Marble from NASA Earth Observatory
Unequal Heating Drives Air and Ocean Circulation
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Unequal Heating Drives Air and
Ocean Circulation
Global Ocean and Atmospheric Circulation Determine Earth’s Climate Patterns
A basic understanding of these circulation patterns will help you grasp the global, regional and local ramifications of the
changes humans are making to our atmosphere and ocean.
Polar Climates
Moist mid-latitude climates:
30°-50° N and S of the equator
Dry climates:
20°-35° N and S of the equator
Tropical climates:
15° to 25° N and S of equator
Dry climates:
20°-35° N and S of the equator
Moist mid-latitude climates:
30°-50° N and S of the equator
Polar Climates
Map Image: NOAA
Uneven heating of the Earth’s surface, combined with the transfer of
Energy by Wind and Ocean Determines Latitudinal Climate Zones 7
Unequal Heating Drives Air and
Ocean Circulation
Global Ocean and Atmospheric Circulation Determine Earth’s Climate Patterns
Assignment
This video summarizes how ocean and atmosphere serve to redistribute heat on the planet’s
surface.http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=11056
8
Describing Climate
.
The
Köppen
climate
classification is based on the
idea
that
vegetation
associations seen on the
landscape
are
the
expression of the climate in
which they evolved. Climate
classification maps created
using the Köppen climate
classification system display
boundaries that are based
on vegetation distribution,
which in turn provides a
“proxy”
indication
of
seasonal temperatures and
precipitation.
Today
the
classification also employs
quantitative
climatological
data in assigning boundaries
between units.
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Describing Climate using the Köppen Climate Classification System
Describing Climate
.
Activity:
To learn more about the classification
scheme we will be using in the map
activity, go to the website linked below
and look at the designations around
the world. For instance, the Sahara
desert in N. Africa has for its
designator B - dry arid and semiarid
climates, characterized by actual
precipitation less than a specified
threshold value set equal to the
potential evapotranspiration. If you do
not understand some of the terms
(e.g., potential evapotranspiration),
don’t worry. You can certainly do some
exploration on your own. Since the
annual precipitation of this area is less
than 50% of this threshold, it is BW
(desert climate). The third letter “h”
indicates that the coldest month has an
average temperature above freezing.
Find your location on the map. What is
the letter designation of your area of
interest, and what does it describe, in
climate terms?
Pidwirny, M. (2011). Köppen Climate Classification System.
http://www.eoearth.org/view/article/162263
Describing Climate using the Köppen Climate Cassification System10
Describing Climate
.
To learn more about the classification
scheme, go to the website link below
and look at the designations around
the world. For instance, the Sahara
desert in N. Africa has for its
designator B - dry arid and semiarid
climates, characterized by actual
precipitation less than a specified
threshold value set equal to the
potential evapotranspiration. Since the
annual precipitation of this area is less
than 50% of this threshold, it is BW
(desert climate). The third letter “h”
indicates that the coldest month has
an average temperature above
freezing. You don’t need to remember
the specifics of the naming system,
just remember that the Köppen
Classification System is used to
describe climate in different regions,
because you will encounter it later in
the mapping activity.
Pidwirny, M. 2011. Tropical Moist Climates- A Climate Type.
http://www.eoearth.org/view/article/162264/
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II. Climate Change
You’ve just explored the basic –physical science behind the positions of Earth’s climate zones. Within
these zones there is significant variation that result from the influences of topography and proximity to
water bodies and ice, soil and substrate, and vegetation. These factors contribute to the complex
system of biomes we have on the Earth’s surface. Also, weather conditions vary from year to year
because of ocean and atmospheric conditions, resulting in extreme events such as droughts, floods,
hurricanes and typhoons. In some regions, events such as these are periodic and quasi-periodic and
cultures have developed important redundancies in their production systems and storage strategies to
ensure the availability of food in times when production conditions are suboptimal.
A stable and predictable climate has enabled
agriculturists to provide reliable harvests and a constant
food supply for their communities. Thousands of years of
human innovation has resulted in crop varieties, food
animals and agricultural practices and decision making
that are finely adapted to each of the
unique
environmental conditions where traditional agriculture has
taken place. But what if those stable and predictable
climate conditions disappear? What do you think the
consequences of a warming climate will be on the global
food production system? How will these changes impact
the other parts of the global food system?
The next section of this slide set is a short presentation about climate change. This is in preparation
for a climate and biome mapping activity that will be conducted next class.
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II. Climate Change
The 30 Second Lesson on Climate Change:
Amount and rate of energy entering the Earth system = energy exiting, no
change
Amount and rate of energy entering the Earth system =/= energy exiting,
change occurs
•
The amount of radiation from the Sun on human time scales does not change (solar
The
OnesoMinute
Lesson
on Climate
Change:
constant),
the only thing
that can cause
warming is changing
the rate at which
energy leaves the Earth system.
•
When the rate of heat energy leaving the system is hindered by molecules in the air
that absorb energy and reflect it back to Earth instead of releasing it to space, heat
builds up and increases the temperature of the system.
•
By adding greenhouse gases into the atmosphere, we increase the amount of gases
in the air that absorb energy, so energy is not released to space as fast as it
accumulates.
•
The rate of heat accumulation is increased because (1) we are moving carbon out of
fossil fuel reservoirs, combusting it, and releasing into the atmosphere as CO2, and
(2) once greenhouse gases (like CO2) are increased in the atmosphere, these
molecules persist for decades and serve to retain the heat energy in the system.
•
This is the mechanism by which our climate warms.
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II. Climate Change
When the rate of heat energy leaving the system is hindered by molecules in the air that
absorb energy and reflect it back to Earth instead of releasing it to space, heat builds up and
increases the temperature of the system.
You may remember that the Earth is a
closed system with respect to matter,
but is an open system with respect to
energy.
About 29% of incoming
sunlight is reflected back to space by
bright particles in the atmosphere or
bright ground surfaces, which leaves
about 71%t to be absorbed by the
atmosphere (23%) and the land
(48%).
For the energy budget at Earth’s
surface to balance, processes on the
ground must get rid of the 48% of
incoming solar energy that the ocean
and land surfaces absorb.
(Source: NASA Earth Observatory).
If we do not lose energy at the rate in
which we obtain it, the system warms.
The Earth System is our Climate System
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II. Climate Change
• The amount of radiation from the Sun on human time scales does
not change (solar constant), so the only thing that can cause
warming is changing the rate at which energy leaves the Earth
system.
Changes in the Sun’s luminosity has an effect on the
Earth’s climate on the scale of tens of millions of years, but
do not account for the recent warming of our planet.
Earth’s eccentric orbit around the Sun and changes in the
tilt of Earth’s axis with respect to the Sun affect climate on
geological time scales of 100,000 -10,000 years, and
cannot account for the recent warming of our planet.
Its Not an Increase in the of Amount of Energy Coming in,
but the Rate of Energy Transfer of Solar Energy Out
Images: NASA Earth Observatory/
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II. Climate Change
•
By adding greenhouse gases into the atmosphere, we increase the amount of gases in
the air that absorb energy, so energy is not released to space as fast as it
accumulates.
•
The rate of heat accumulation is increased because (1) we are moving carbon out of
fossil fuel reservoirs, combusting it, and releasing into the atmosphere as CO2, and
(2) once greenhouse gases (like CO2) are increased in the atmosphere, these
molecules persist for decades and serve to retain the heat energy in the system.
Review Terminology:
Reservoir: the volume
or mass of matter or of
energy stored in a
system
Residence Time: the
average amount of time
that matter remains in a
reservoir
Flux:
describes
the
movement
of
mass
and/or energy between
reservoirs
Image: NASA GLOBE
In your notes: Identify the fluxes and reservoirs in the carbon cycle that are contributing to our
warming climate.
Changing Where our Carbon is in the Earth System
16
II. Climate Change
Fast and Slow Carbon
Watch this short video that describes the idea of residence time by discussing “fast carbon and slow
carbon”. You will see that this video is talking about fluxes between carbon found in reservoirs in the
lithosphere and biosphere. By fast carbon, the video is referring to carbon’s short residence time (in a
banana) and long residence time (in coal). By moving carbon in fossil fuels out of storage and into the
atmosphere, we are adding carbon to the atmosphere much faster than it can be removed by Earth
system processes.
Review:
Dissolved CO2 in the Ocean has a residence
time of about 500 years in the reservoir in the
hydrosphere.
The residence time of carbon in life forms is
variable, depending on their life span, and how
rapid they decay: reservoir of the biosphere.
Coal, petroleum and natural gas have a
residence time of millions of years in the
lithosphere, however this is reduced through
use of fossil fuels.
Climate Bits: Fast Carbon, Slow Carbon
Credit: http://climatebits.umd.edu/
CO2 has a residence time of hundreds of
years in the reservoir of the atmosphere.
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II. Climate Change
Climate is changing. How can we prepare for the future? How can we ensure that our agricultural
production systems are responsive to the future changes and are able to provide sufficient food to
people around the globe?
We can’t predict the future, but by understanding the processes that take place within the Earth
system, and by describing the interactions between air, water, life and land quantitatively, we are
able to develop accurate projections of future conditions that can be used in planning for food
production on a warmer Earth.
How Can We Prepare for a Warming World?
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II. Climate Change
Climate Models Allow us to Project Future Climate Changes
…and allow us to begin to prepare for a warmer world.
A quantitative understanding of the
processes and fluxes in the Earth
system is critical to our ability to
understand the changes that are
occurring in our climate. The climate
system is both affected by and in turn
impacts the overall system in direct
and complex ways and it operates at
local regional and global scales.
A quick glance at this diagram shows
the complexity of the Climate System
– and the many interactions and
processes at work. This is why
supercomputers are needed to run
climate models!
In the mapping activity, you will be
using the output from Global Climate
Models (GCMs) to project future
changes in climate, and consider how
these changes will impact the global
food system.
Image: USGCRP 19
II. Climate Change
Reading Assignment:
You have already read an except of Steve Easterbrook’s blog post. Now read the entire post, paying
attention to his discussion of Why Systems Thinking, as he refers to how we build understanding of
the climate system. There are additional links to other excellent resources that delve deeper into
greenhouse gases and Earth system feedbacks if you are interested.
http://www.easterbrook.ca/steve/2013/08/why-systems-thinking/
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II. Climate Change
Writing Assignment (one paragraph)
Suggest one way that a changing climate could impact the global food system: food production,
food distribution, or food quality. You can use the diagram on the left as an example. Create a
diagram showing appropriate feedbacks/ fluxes linking 3 or more spheres. Bring your paragraph
and diagram to class.
Crop
failure
More
frequent
droughts
And
floods
Warmer
atmosphere
Climate
warming
Enhanced
water cycle
CO2 release
from lithosphere
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II. Climate Change
Make a Note:
Before you complete this activity, make notes about any questions that you have
that can be discussed by the group
Thanks for completing this tutorial. It will allow us to have richer conversations in
our face-to-face meeting.
“We cannot solve our problems with the same thinking we used when we
created them.” – Albert Einstein
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II. Climate Change
Moving Forward
As you learn more about Earth’s Climate
and global change, or even as you simply
think about what is happening in the natural
world around you, keep in mind the concept
of the Earth system, with its spheres,
reservoirs of matter and energy, and
processes that drive matter and energy
fluxes from one sphere to another. These
concepts can help you better understand
the very dynamic nature of our planet, even
when processes happen at rates that are
much more gradual than the eruption of a
volcano or flooding that results from a wild
storm. The global food system is
inextricably linked and responsive to the
Earth system, and a warming climate is a
factor that needs to be addressed in any
effort to address global food security.
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II. Climate Change
Revised and expanded version developed for inclusion in module,
“Addressing the Wicked Problem of Global Food Security,” (September 2015) Russanne Low
Original Artwork- Jenn Glaser and Russanne Low, ScribeArts for the GLOBE Program
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