1 / 38

Chapter 3 – Changing Climates

Pages 366 - 392. Chapter 3 – Changing Climates. 3.1 – The Great Cooling (pages 368 – 374). The Cenozoic Era extends back 65 million years Cypress Hills interprovincial park contains sediments from the Cenozoic Era. Rising Mountains. The Cenozoic Era in divided into 2 periods:

homer
Download Presentation

Chapter 3 – Changing Climates

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Pages 366 - 392 Chapter 3 – Changing Climates

  2. 3.1 – The Great Cooling (pages 368 – 374) • The Cenozoic Era extends back 65 million years • Cypress Hills interprovincial park contains sediments from the Cenozoic Era

  3. Rising Mountains • The Cenozoic Era in divided into 2 periods: • Tertiary Period: 65 – 1.7 million years ago • Quaternary Period: 1.7 million years ago – present

  4. North American and Pacific Plates collisions are at most intense at beginning of Cenozoic

  5. Plate activity also resulted in the northward migration of the North American Plate • North American climate got cooler • Climate was cool enough to form glaciers • Glaciers are responsible for carving out the familiar jagged features of the Rockies • Icy process began ~1.7 million years ago

  6. The Retreating Bearspaw Sea • During the late Cretaceous Period, much of southern Alberta was submerged under the Bearspaw Sea • Beginning of Cenozoic Era, the Bearspaw Sea had retreated to the southeast • Cenozoic sedimentary rock outcrops are evidence of rivers pouring sediment from the Rocky Mountains

  7. The Retreating Bearspaw Sea

  8. A Cooling Trend • There was a significant drop in average global temperatures during the first 15 million years of the Tertiary Period • Caused drastic changes to Alberta’s animal and plant life • Tropical forests became temperate evergreen forests

  9. ~2/3 of the way through the Tertiary Period Alberta was thought to resemble present day Louisiana

  10. Rise of the Mammals

  11. Rise of the Mammals • Surviving mammals at the end of the cretaceous period were mainly small rodents • By 40 million years ago, new forms of mammals appear in the fossil record • Ancestors of modern hooved herbivores • Flesh-eating carnivores • Large-brained primates

  12. Grasses, Grazers, and Big Predators • 35 million years ago, grasslands dominate Alberta’s landscape • Grasses are well suited for the cooler and drier climate • Grasslands became home to huge grazing herds and the predators that stalked them

  13. Evidence for a Cooling Trend • The overall cooling trend during the Tertiary Period was just one of many throughout Earth’s past • Evidence can be found in sedimentary rock • Absence of tree pollen in present-day tropical climates suggests that the past climate was much cooler • Presence of pollen in sedimentary rock of present-day polar regions suggests that climate was warmer in past

  14. 3.1 Summary • The end of the Mesozoic Era, 65 million years ago, saw the end of the Dinosaurs • Tectonic activity forms the Rocky Mountains and drains the Bearspaw Sea • An overall global cooling trend during the Tertiary Period resulted in a grassland Alberta that supported large herds of grazers and predators

  15. 3.2 – The Icy Epoch (pages 375 – 381)

  16. The Big Freeze • 1.7 million years ago, the climate became so cold that snow began to accumulate year after year in the polar regions • This marked the beginning of the Pleistocene Epoch • Layer upon layer of snow became compacted into sheets of ice (glaciers) • Glacier: a large river of ice that forms on land and moves under the influence of gravity

  17. When ice sheets reach a critical mass, they begin to slowly flow outward toward the equator like a viscous fluid • Earth’s current continental ice sheets cover nearly all of Antarctica and Greenland • When the edge of the glacier reaches the sea, huge chucks fall off in a process called “calving”

  18. Ice Age: a period during which ice sheets cover parts of the Northern and Southern Hemispheres • Glaciation: a period during which polar ice sheets advance to cover large regions of North America and northern Europe • Scientists believe that during the Pleistocene, there were at least four major glaciations

  19. Giants of the Pleistocene • During the chilly Pleistocene Epoch, large mammals had the advantage • Ie. wooly mammoths, wooly rhinoceros, modern horses, llamas, reindeer • Vicious predators stalked herds of large grazing mammals • Ie. American lions, short-faced bears, sabre-tooth cats

  20. 3.2 Summary • The cooling of the Tertiary Period reached a climax during the first part of the Quaternary Period – The Pleistocene Epoch • 4 major glaciation events occurred during the Pleistocene Epoch • Enormous sheets of ice continue to shape the world today

  21. 3.3 – Explaining and Predicting Climate Change (pages 382 – 389) • Weather: variables such as temperature, precipitation, and humidity is a certain place at a particular time • Climate: the average of daily and seasonal weather events that occur in a region over a long period of time (ie. 30 years)

  22. The Epoch of Recent Time - Holocene • The Holocene Epoch began ~10 000 years agoat the time of the great melt following the last glaciation • The rapid melting of glaciers opened ice free corridors that allowed individuals living in the North to migrate south

  23. Fluctuating Climate • Some changes in Earth’s climate seem to be chaotic in nature, while others seem to follow a pattern • Evidence contained in rock strata around the world suggests that during most of its history, Earth was warmer than it is today

  24. Possible Causes of Glaciation Periods • Interactions between Earth systems are very intricate, it is likely that glaciation periods are a result of the combination of the following effects: • Continents heading North • The ocean is a heat pump • Volcanic activity • Earth’s wobbly axis • Varying Sun intensity

  25. The Continents Heading North • Glaciation events seem to occur when large land masses are near the poles. • Continental ice sheets must form on land to cause glaciations • Forming ice sheets cause further cooling since they reflect much of the Sun’s solar energy; causing further cooling

  26. The Ocean is a Heat Pump • Oceans contain giant convection currents that transport heat around the globe • This has a warming effect on some areas of the world and a cooling effect on others • The warm circulating currents are known as the “global conveyor”.

  27. Volcanic Activity • Volcanoes are believed to be major contributors to past mass extinction events. • Volcanoes can also contribute to short-term fluctuations in climate • Mt. Pinatubo caused a drop in global average temperatures for at least 2 years

  28. Earth’s Wobbly Axis • Proposed by Milutin Milankovich • The amount of solar energy reaching the polar regions can be affected by: • The shape of Earth’s orbit • The tilt of Earth’s axis of rotation • The wobble of the axis of rotation

  29. Sun’s Changing Intenstiy • The Sun does not always shine with the same intensity • Intensity seems to follow a regular pattern determined by the pattern of sunspots. • During times of frequent sunspot activity, solar energy output is greater

  30. The Greenhouse Effect • Methane and carbon dioxide are naturally occurring greenhouse gases that trap heat near Earth’s surface • Without the greenhouse gases in our atmosphere, Earth would be much cooler • Volcanic eruptions, swamps and forest fires are all natural sources of greenhouse gases

  31. The Enhanced Greenhouse Effect • Human activities, such as the combustion of fossil fuels can increase the amount of greenhouse gases like carbon dioxide in the atmosphere • Many scientists believe that the sudden increase in the amount of carbon dioxide in the atmosphere during the last century has add a significant effect on the global average temperature

  32. 3.3 Summary • The Halocene Epoch (10 000 yrs ago – present) • Climate fluctuations in Earth’s past may have been due to a combination of factors: • Moving continents • Global conveyor • Volcanic activity • Wobbly axis • Fluctuating Sun intensity • Understanding climate change in the past can help us predict climate change into the future

More Related