For this topic, read the supplemental notes below then read p and answer the questions below:

Pangaea had formed and soon after a mass extinction of marine and continental life. Start of the Mesozoic era. Mesozoic – Middle life Separated into three periods: Triassic, Jurassic, Cretaceous periods

Started right after the end of the Permian extinction Supercontinent is still together – Pangaea which means “all the land” Hot and dry climates across the Earth (about 3-5 degrees hotter than averages today). Today’s north/south poles weren’t ice-covered, but moist and temperate.

Saw the reptiles begin to flourish on land and very quickly take over. The archosauras (small dinosaurs/reptiles)become dominant predators. First mammals appear  Triassic ended with large marine extinction (20% of species) and smaller continental extinction.

The “golden age” of large dinosaurs. Pangaea begins to break up into the northern and southern supercontinents. Plants began cover large areas (think of the climate). Gymnosperms became dominant. Gymnosperms – Seed-bearing plants and trees Early birds are first seen, evolving from different types of dinosaurs. Major extinction event ends the Mesozoic Era 65 million years ago.

Major event caused another large-scale extinction. Theorized by massive asteroid impact.  Large dust particles / clouds blocked solar energy from reaching the Earth.  Species that depend on photosynthesis or sunlight energy become extint…. That’s a lot of the species.

Pangaea is officially broken up  and the continents continue to slide into their current positions. Large scale cooling marks the beginning of the period. Mammals begin to take over and dominate food chains on land. Early humans appear about 2mya. Grasslands started to dominate worldwide. Plants and animals begin to evolve and look more and more like those of today.

Holocene Epoch began about 10,000 years ago and many of the glaciers began to melt. The ocean plays a large role in as a global conveyor. Global conveyor – system of ocean currents that circulate warm water away from the tropics near the ocean’s surface. This causes some of the continents of Earth to be warmer than others and heat is transferred.

The cooling trend continued to the point of another ice age – Pleistocene Epoch 1.7mya Large glaciers covered the Earth and grew/receded over until about 10,000 ya. Glaciers – large rivers of ice that form on land. Much of Canada, including Alberta, is covered in ice. Much of this ice still remains in Antarctica, Greenland, and Alberta’s Rocky Mountains.

Often, computer models are shown to try and predict future effects on Earth’s climate. This can be difficult and complex. Look at graphs on p. 388 in the text. We have seen an overall rise in carbon dioxide levels and a rise in temperature over the last 100 years. The Intergovernmental Panel on Climate Change continues to be the major scientific group studying the effects and reasons behind climate change.

“An increasing body of observations gives a collective picture of a warming world and other changes in the climate system... There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities” As of 2008, there no scientific body of national or international standing has maintained a dissenting opinion.

Climate change and future changes are difficult to predict. Effects can have major impacts on human systems, economies, and growth. However, the specific impacts will be talked about in our sequel – Science 30 Hope you enjoyed the semester….