7.1 Evolution of Earth's Atmosphere

7.1 Evolution of Earth's Atmosphere

7.1:  I can analyze the development and changes of Earth's atmosphere over time.

• describe the different atmospheres that have occurred on Earth and relate them to global climate

• evaluate the reasons that Earth’s atmosphere has changed over time.

• compare and contrast Earth’s atmosphere to other planets and their climates.

Earth's Atmosphere

• Earth’s atmosphere is 21 percent oxygen, 78 percent nitrogen, and one percent trace gases.

• The composition of the atmosphere can change due to human, biologic, and geologic activity

Multiple Choice

What is the most abundant gas in Earth's atmosphere today?

• oxygen

• troposhpere

• nitrogen

• argon

Multiple Choice

What gas makes up 21% of Earth's Atmosphere today?

• argon

• nitrogen

• oxygen

• methane

Greenhouse gases

Sunlight passes through the atmosphere and is absorbed by the Earth’s surface, warming it. 

Greenhouse gases act like a blanket by trapping heat near the surface and raising the temperature.

It is a natural process that warms the planet.

Natural vs. Man-made Greenhouse Gases

• Many greenhouse gases occur naturally in the atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, 

Man-made Greenhouse Gases

• Carbon Dioxide (CO2): Carbon dioxide enters the atmosphere through the burning of fossil fuels

• Methane (CH4): Methane is emitted during the production and transport of fossil fuels, livestock and agriculture

• Nitrous Oxide (N2O): Nitrous oxide is emitted during agricultural and industrial activities

Impacts of Greenhouse Gases

• As global carbon emissions have increased, so have global temperatures.

• Rising global temperatures threaten human health, increase the risk of some types of extreme weather, and damage ecosystems.

• As oceans warm and polar ice caps melt, sea levels are rising, endangering coastal areas.

Multiple Choice

Which of the following are greenhouse gases?

• carbon dioxide

• methane

• water

• all of the above

Multiple Choice

Fossil fuel use is believed to be one factor leading to global warming.

• true

• false

Multiple Choice

Which of the following is thought to be evidence of climate change due to global warming?

• warming oceans

• sea level rise

• extreme weather

• all of the above

Earth's atmosphere has changed over time.

The first atmosphere was hot and mostly hydrogen and helium.

Outgassing

release of gases from volcanoes

Evolution of the atmosphere

• The composition of Earth’s atmosphere has changed over geologic time.

• Earth’s atmosphere is unique in the solar system in that it contains substantial oxygen

• The atmosphere of the young Earth was changed by outgassing and early photosynthetic life.

• Early photosynthetic life such as cyanobacteria (blue-green algae) consumed carbon dioxide and generated oxygen.

• It was only after early photosynthetic life generated oxygen that animal life became possible.

Earth's Atmosphere

• The atmospheres of Earth, Mars, and Venus apparently had very different paths toward the evolution of their current conditions.

• Many factors may have influenced this, including distance from the Sun, planetary mass, the nature of the planets’ interiors, the presence of a large moon, and the origin and nature of each planet’s early atmosphere

Multiple Choice

Which gas makes up the largest percentage of Earth's atmosphere?

• nitrogen

• argon

• oxygen

Multiple Choice

This gas was in high concentrations in the early atmosphere, and later condensed to form the Earth's oceans.

• oxygen

• sulfur dioxides

• carbon dioxide

• water vapor

Multiple Choice

This gas was in high concentrations in the developing atmospheres and later dissolved into rainwater, added to the oceans, then settled to the bottom of the ocean.

• oxygen

• argon

• carbon dioxide

• water vapor

Multiple Choice

Why is Earth's atmosphere important?

• It is beautiful.

• Life on Mars could not exist without it.

• It prevents pollution from happening.

• Life on Earth could not exist without it.

Multiple Choice

What was the effect of volcanoes on the Earth's early atmosphere?

• Volcanoes had no effect on the atmosphere

• Volcanoes released water vapor

  Volcanoes released gases and water vapor

• Volcanoes changed the landscape

Multiple Choice

The earliest atmosphere on Earth was mostly made of Hydrogen and Helium.

• true

• false

Multiple Choice

The process of volcanoes releasing gases into the atmosphere is called...

• outgassing

• condensation

• evaporation

• erosion