When Earth emits the same amount of energy as it absorbs, its energy budget is in balance, and its average temperature remains stable. Jump to A Balance
Culture, Climate Science & Education
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Principle One: The Sun is Primary
The Cultural Value is Gratitude
Episode One: Coyote Stories
Episode 1: Coyote Stories
Transcript with Description of Visuals
Audio |
Visual |
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Audio Voice Over in Alyssa Pretty On Top’s voice: |
Visual Snow covered field with a single old tree two hundred yards away. A single animal track crosses the field and heads toward the tree. |
Audio Voice Over continues: |
Visual Snowy mountain canyon with high cliffs on both sides and conifers in the bottom and on the mountain sides. |
Audio My name is Alyssa Pretty On Top, and I want to tell you about the creation stories of our People. These are Coyote stories. They are sacred stories, passed down for thousand of years. |
Visual Children, including Alyssa, are moving around in an almost dance-like way. They dressed mostly in ribbon dresses and ribbon shirts and moccasins. Some have masks on, others are dressed as animals. |
Audio And just as countless generations have done, we are coming together on this snowy winter evening for dinner and a night of storytelling. |
Visual In the large room of the Longhouse the people, children and some adults, are seated in a large circle. At the far side the elders are seated, and in front of them on the floor are four large buffalo robes. |
Audio I am excited to hear my elders tell some of the stories again. I have waited all year. |
Visual Alyssa Pretty On Top and her grandfather are seated. Her grandfather is telling a story and motioning with his hands as he speaks. |
Audio Alyssa’s Grandfather: |
Visual Alyssa’s grandfather is telling the story. |
Audio Alyssa’s Voice Over continues: |
Visual A girl with an animal mask is acting out a character in one of the stories, marching and moving her hands like paws, pantomiming a part of the story. Other children, boys and girls are watching and acting out their parts of the story. |
Audio A voice of one of the young people acting in a Coyote story being told: |
Visual Children laughing. |
Audio Alyssa’s Voice Over continues: |
Visual Alyssa’s grandfather telling part of a story. A group of young children lying on the buffalo robes stare up at Alyssa’s grandfather. |
Audio Alyssa’s Grandfather: |
Visual Alyssa’s grandfather talking. |
Audio Alyssa’s Voice Over continues: |
Visual A girl reading a Coyote Story from a storybook to a dozen or so kids seated on the buffalo robes. |
Audio Alyssa’s Grandfather telling one of the stories: |
Visual Alyssa’s grandfather talking. |
Audio Alyssa’s Voice Over continues: |
Visual The rotating Earth as seen from space, the Sun shining in the distance. Slowly, the Sun moves behind the Earth and the day changes to night and cities light up. |
Audio Chaney Bell, a cultural leader: |
Visual Chaney Bell talking to the group. |
Audio Alyssa’s Voice Over continues: |
Visual Children lying on buffalo robes, listening to Alyssa’s grandfather. Girls with acting out a story. |
Audio Alyssa’s Grandfather telling one of the stories: |
Visual Alyssa’s grandfather talking. Children listening. |
Audio Sound of wind blowing through trees. |
Visual Snow falling through bare branches. Tall snow covered mountains. |
Audio |
Visual The following credits in white text over a black background: |
Principle 1
What You Need to Know About Principle 1: The Sun is Primary
This principle is about the Earth’s energy balance and how the sun affects the earth. The role of solar energy — how the atmosphere first filters sunlight when it meets the earth, how it is absorbed by the land and water surfaces, turned into infrared heat that radiates from the surface back into space — is important for understanding the reason we have seasons, the cause of ice ages, and the “greenhouse effect” whereby some of the outgoing infrared heat is captured by certain atmospheric gases, thereby warming the atmosphere, making life on Earth possible.
click the topics to learn what you need to know about Principle 2
- Warming the Planet
Sunlight reaching the Earth heats the land, ocean, and atmosphere. Some of that sunlight is reflected back to space by the surface, clouds, and ice. Much of the sunlight that reaches Earth is absorbed and warms the planet. Jump to Warming the Planet
- A Balance
- The Reasons for the Seasons
The tilt of Earth’s axis relative to its orbit around the Sun results in predictable changes in the duration of daylight and the amount of sunlight received at any latitude throughout a year. These changes cause the annual cycle of seasons and associated temperature changes. Jump to The Reason for the Seasons
- Ice Ages
Gradual changes in Earth’s rotation and orbit around the Sun change the intensity of sunlight received in our planet’s polar and equatorial regions. For at least the last 1 million years, these changes occurred in 100,000-year cycles that produced ice ages and the shorter warm periods between them. Jump to The Reason for the Ice Ages
- Changes in the Sun’s Energy Output?
A significant increase or decrease in the Sun’s energy output would cause Earth to warm or cool. Satellite measurements taken over the past 30 years show that the Sun’s energy output has changed only slightly and in both directions. These changes in the Sun’s energy are thought to be too small to be the cause of the recent warming observed on Earth. Jump to In the Sun’s Energy Output
Principle 1a
Warming the Planet
The energy that drives the climate system and that makes life possible on earth comes from the Sun.
When the Sun's energy reaches the Earth, it does so as shortwave radiation. That shortwave radiation is partially absorbed by land, water, and the atmosphere, the rest is reflected back into space. Read more…
Warming the Planet
The energy that drives the climate system and that makes life possible on earth comes from the Sun.
When the Sun's energy reaches the Earth as shortwave radiation. That shortwave radiation is partially absorbed by land, water, and the atmosphere, the rest is reflected back into space.
A key thing to remember is that the energy absorbed by the earth is converted into heat. That heat makes Earth habitable. It radiates back out into the atmosphere as longwave radiation.
The diagrams below show the amount of energy absorbed and reflected in watts per square meter.
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Principle 1b
A Balance: Energy In Needs to Equal Energy Out
When Earth emits (releases back into space) the same amount of energy as it absorbs from the sun, its energy budget is in balance, and the Earth’s average temperature remains stable.
The Earth’s climate system moves solar heat from the equator and toward the poles.
It also moves heat from the Earth’s surface and lower atmosphere back to space. If it didn’t, the earth would endlessly heat up. It would become like Venus, and it would be unable to support life. Read more…
A Balance: Energy In Needs to Equal Energy Out
When Earth emits (releases back into space) the same amount of energy as it absorbs from the sun, its energy budget is in balance, and the Earth’s average temperature remains stable. In other words, energy in equals energy out.
The Earth’s climate system moves solar heat from the equator and toward the poles.
It also moves heat from the Earth’s surface and lower atmosphere back to space. If it didn’t, the earth would endlessly heat up. It would become like Venus, and it would be unable to support life.
When the flow of incoming solar energy is balanced by an equal flow of heat back into space, Earth is in a kind of equilibrium—scientists call it a “radiative equilibrium”—and the global temperature is relatively stable.
Anything that increases or decreases the amount of incoming or outgoing energy disturbs Earth’s radiative equilibrium and global temperatures will rise or fall in response.
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Principle 1c
The Reason for the Seasons
The seasons are caused by the tilt of the Earth (remember the Earth is tilted on its axis).
When the northern hemisphere where we live is tilted toward the sun, we have summer.
When it is tilted away from the sun, we have winter.
The tilt of Earth’s axis relative to its orbit around the Sun results in predictable changes in the length of daylight and the amount of sunlight received at any latitude throughout a year. We call these changes “seasons” — spring, summer, fall, and winter. Read more…
The Reason for the Seasons
The seasons are caused by the tilt of the Earth (remember the Earth is tilted on its axis).
When the northern hemisphere where we live is tilted toward the sun, we have summer.
When it is tilted away from the sun, we have winter.
The tilt of Earth’s axis relative to its orbit around the Sun results in predictable changes in the length of daylight and the amount of sunlight received at any latitude throughout a year. We call these changes “seasons” — spring, summer, fall, and winter.
This is how it works: As the Earth travels around the Sun, it remains tipped in the same direction, toward the star Polaris (the north star).
This means that sometimes the northern half of the Earth is pointing toward the Sun (summer), and sometimes it is pointing slightly away (winter).
The times when the Earth's orbit is tilted most toward or away from the Sun are called solstices, and they mark the seasons of summer and winter.
When the northern hemisphere is tilted toward the Sun, the southern hemisphere is tilted away. This explains why the hemispheres have opposite seasons — when it is summer in Montana, it is winter in Argentina and Australia and vice versa.
Halfway between the solstices, the Earth is neither tilted directly toward nor directly away from the Sun. At these times, called the equinoxes, both hemispheres receive roughly equal amounts of sunlight. Equinoxes mark the seasons of autumn and spring.
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In the images above, look at how North America is angled away from the sun in December (winter) and how it is angled toward the sun in June (summer).
Principle 1d
The Reason for Ice Ages
Gradual changes in Earth’s rotation and orbit around the Sun change the intensity of sunlight received in our planet’s polar and equatorial regions.
For at least the last 1 million years, these changes occurred in 100,000-year cycles that produced ice ages and the shorter warm periods between them.
In the 1910s, a mathematician named Milankovitch demonstrated how Earth's orbital variations play a role in Ice Ages and other climate variations.
Milankovitch cycles, such as precession of the equinoxes (23,000 years), obliquity (41,000 years) and eccentricity (100,000 and 400,000 year periods) affect the amount of sunlight that radiates to Earth. Read more…
The Reason for Ice Ages
Gradual changes in Earth’s rotation and orbit around the Sun change the intensity of sunlight received in our planet’s polar and equatorial regions.
For at least the last 1 million years, these changes occurred in 100,000-year cycles that produced ice ages and the shorter warm periods between them.
In the 1910s, a mathematician named Milankovitch demonstrated how Earth's orbital variations play a role in Ice Ages and other climate variations.
Milankovitch cycles, such as precession of the equinoxes (23,000 years), obliquity (41,000 years) and eccentricity (100,000 and 400,000 year periods) affect the amount of sunlight that radiates to Earth.
Milankovitch cycles are measured using data derived from marine sediments, landforms, loess (fine, windblown silt), cave features, and astronomical observations and calculations. Understanding the Milankovitch cycles helps with reconstructing past climate variability at 100,000 year and longer time scales.
At the present time, the Milankovitch cycles are at a point that place the Earth in an interglacial — a warm period of relatively stable climate. This warm period is predicted to continue for tens of thousands of years, but is not expected to generate warmer climates over the period of decades. For this reason, recent climatic changes are not considered to be attributable to the natural cycles described by Milankovitch.
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Planets orbiting the Sun follow elliptical (oval) orbits that rotate gradually over time.
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Planets orbiting the Sun follow elliptical (oval) orbits that rotate gradually over time (apsidal precession). The eccentricity of this ellipse is exaggerated for visualization. Most orbits in the Solar System have a much smaller eccentricity, making them nearly circular.
Principle 1e
Changes in the Sun’s Energy Output
A significant increase or decrease in the Sun’s energy output would cause Earth to heat up or cool down.
Satellite measurements taken over the past 30 years show that the Sun’s energy output has changed only slightly and in both directions.
These changes in the Sun’s energy are thought to be too small to be the cause of the recent warming observed on Earth. Read more…
Changes in the Sun’s Energy Output
A significant increase or decrease in the Sun’s energy output would cause Earth to heat up or cool down.
Satellite measurements taken over the past 30 years show that the Sun’s energy output has changed only slightly and in both directions.
These changes in the Sun’s energy are thought to be too small to be the cause of the recent warming observed on Earth.
Could variations in the amount of energy from the sun alter climate? The short answer is yes. The concept that long-term variations over thousands and millions of years of solar irradiance has affected climate is born out in research. But scientists studying shorter-term variations, including the 22 year solar cycle of solar activity measured between a minimum and maximum period, have determined that the amount of extra solar energy reaching Earth is relatively small, not enough to account for recent climate change.
As shown in the figure below, direct satellite measurements of the Sun’s energy reaching Earth since the late 1970s show no net increase in the Sun’s output (in fact, there has been a slight decrease), while at the same time global surface temperatures have increased. Furthermore, most up-to-date climate models – including those used by the IPCC and researchers at Cornell University – include the effects of the sun’s variable brightness in their calculations. These climate models can’t reproduce the observed temperature trends over the past century or more without including a rise in human-emitted greenhouse gases.
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Principle 1f
Local Relevance
Changes in Solar Radiation Affect Precipitation in the Desert Southwest
Variations in the amount of solar-radiation hitting the earth affect precipitation patterns in the Southwest. More solar radiation means more rain, and vice versa. But why? Scientists say two things account for this pattern.
Precipitation in the Desert Southwest is tied to solar irradiance, though it lags by 3 to 5 years. Droughts coincide with periods of lower solar irradiance, and wet periods coincide with periods of higher irradiance (moist low-pressure development).
More solar radiation means more rain, and vice versa. But why? Scientists say two things account for this pattern.
(1) Varying amounts of solar energy are absorbed by tropical oceans, creating ocean temperatures that are different from what one would expect.
(2) Those cooler or warmer waters then move with the ocean currents to locations where they alter regional atmospheric moisture and pressure patterns, which in turn affect regional precipitation and temperature over the continent, hence changing the amount of rain in the Desert Southwest.
Principle 1g
Misconceptions about this Principle
The Misconception
CO2 was higher in the late Ordovician Period so the earth should have been super hot then. Instead there was an ice age.
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The Science
CO2 was higher in the late Ordovician Period but solar output was much lower, and that explains how an ice age occurred with high CO2 levels.
The science says: during the Ordovician, solar output was much lower than current levels. Consequently, CO2 levels only needed to fall below 3000 parts per million for glaciation to be possible. The latest CO2 data calculated from sediment cores show that CO2 levels fell sharply during the late Ordovician due to high rock weathering removing CO2 from the air. Thus the CO2 record during the late Ordovician is entirely consistent with the notion that CO2 is a strong driver of climate. Read more…
Source: http://www.skepticalscience.com/CO2-was-higher-in-late-Ordovician.htm
The Science
CO2 was higher in the late Ordovician Period but solar output was much lower, and that explains how an ice age occurred with high CO2 levels.
The science says: during the Ordovician, solar output was much lower than current levels. Consequently, CO2 levels only needed to fall below 3000 parts per million for glaciation to be possible. The latest CO2 data calculated from sediment cores show that CO2 levels fell sharply during the late Ordovician due to high rock weathering removing CO2 from the air. Thus the CO2 record during the late Ordovician is entirely consistent with the notion that CO2 is a strong driver of climate.
An argument used against the warming effect of carbon dioxide is that millions of years ago, CO2 levels were higher during periods where large glaciers formed over the Earth's poles. This argument fails to take into account that solar output was also lower during these periods. The combined effect of sun and CO2 show good correlation with climate. The one period that until recently puzzled paleoclimatologists was the late Ordovician, around 444 million years ago. At this time, CO2 levels were very high, around 5600 parts per million (in contrast, current CO2 levels are 389 parts per million). However, glaciers were so far-reaching during the late Ordovician, it coincided with one of the largest marine mass extinction events in Earth history. How did glaciation occur with such high CO2 levels? Recent data has revealed CO2 levels at the time of the late Ordovician ice age were not that high after all.
Past studies on the Ordovician period calculated CO2 levels at 10 million year intervals. The problem with such coarse data sampling is the Ordovician ice age lasted only half a million years. To fill in the gaps, a 2009 study examined strontium isotopes in the sediment record. Strontium is produced by rock weathering, the process that removes CO2 from the air. Consequently, the ratio of strontium isotopes can be used to determine how quickly rock weathering removed CO2 from the atmosphere in the past. Using strontium levels, Young determined that during the late Ordovician, rock weathering was at high levels while volcanic activity, which adds CO2 to the atmosphere, dropped. This led to CO2 levels falling below 3000 parts per million which was low enough to initiate glaciation — the growing of ice sheets.
Thus arguments that Ordovician glaciation disproves the warming effect of CO2 are groundless. On the contrary, the CO2 record over the late Ordovician is entirely consistent with the notion that CO2 is a strong driver of climate.
Source: http://www.skepticalscience.com/CO2-was-higher-in-late-Ordovician.htm
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Principle 1
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