Past Climate Change (Long-term climate evolution)

PQS8.1. DESCRIBE the broad features of climatic evolution over Earth’s history

Factors that influence the long term evolution of climate

Changes in solar radiation

Concentration of greenhouse gases in the atmosphere

Positions of the continents

PQS8.2. DESCRIBE the broad features of climatic evolution over Earth’s history

What has been the general trend in Earth’s temperature over the past 65 million years?

Earth’s temperature has generally been decreasing.

PQS8.3. DESCRIBE the broad features of climatic evolution over Earth’s history

What role did organisms play in causing the Permo-Carboniferous glaciations 300-270 million years ago?

Oxygen-producing organisms evolved and the oxygen oxidized a lot of methane.

PQS8.4. DESCRIBE the broad features of climatic evolution over Earth’s history

Which major glaciation in Earth’s history resulted in the deposition of most of the coal deposits we use as fossil fuels today?

The Permo-Carboniferous glaciations 300-270 million years ago.

Amplifying feedback

Accelerates change, driving systems toward new, often more extreme states.

Stabilizing feedback

Self-regulating, balancing force that reduces change to return systems to a stable equilibrium.

PQS8.5. DESCRIBE the broad features of climatic evolution over Earth’s history

How could the Earth have become a snowball?

amplifying feedback between ice cover & albedo

Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

What kind of feedback is the ice-albedo feedback?

(1) during the formation and growth of continental ice sheets

2) during the melting and disintegration of continental ice sheets

What kind of feedback is the ice-albedo feedback?

(1) during the formation and growth of continental ice sheets→amplifying feedback

2) during the melting and disintegration of continental ice sheets→ amplifying feedback

Feedback loop

a process that amplifies or dampens an initial change in Earth's temperature

-an increase in sea ice cover

-an increase in boreal forest area

Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

During an ice age, when there’s lots of ice piled up on land, what is sea level like, compared to a warmer time?

lower sea level compared to a warmer time

Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

During an ice age, when there’s lots of ice piled up on land, what is Earth’s albedo like, compared to a warmer time?

higher albedo compared to a warmer time.

PQS8.8. Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

How would the rise of oxygenic photosynthetic organisms influence Earth’s climate, at a time when the atmospheric methane concentration was fairly high?

The would combine with methane CH4 to make CO2 and decrease Earth’s temperature

PQS8.9 Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

How could having all continents bundled near the Equator help trigger a global glaciation?

Warm temperatures in the tropics would keep silicate weathering rates high.

PQS8.10. Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

What is the most likely mechanism that helped Earth escape from the “snowball” scenario?

volcanic activity

PQS8.11. Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

When large areas of continents are covered by ice, what happens to the rate of chemical weathering?

It decreases because the continents are mostly covered with ice and not exposed to the atmosphere.

PQS8.12. Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

Vast swamps covered large areas of land during the Carboniferous era, increasing the burial of organic carbon. This resulted in an atmosphere with..

higher O2 content and lower CO2 content.

Due to large areas of land, burial of carbon

In this way, a lot of organic matter, was produced and buried at this time. This created the cool beds of the carbon. Ines era that we used today as an Energy source carbon, burial decreases atmospheric CO2 and Therefore amplifies cooling.

PQS8.13. Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

The Cretaceous was a period with predominantly … sea level.

This might have contributed to warming/cooling the Cretaceous climate

PQS8.13. Based on albedo, solar radiation, and atmospheric gases, CONSTRUCT logical chains of events that would result in major glaciations or warm periods on Earth

The Cretaceous was a period with predominantly higher sea level.

This was caused by a combination of high volcanic activity increasing ocean basin volume and a "hothouse" climate that left the planet largely ice-free.

This might have contributed to warming the Cretaceous climate

Because water has a lower albedo(reflectivity) than land or ice, these expanded seas absorbed more solar radiation, which helped maintain and reinforce the warm, equable global climate.