Watch for Week 8/9 Review Assessment

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Chrystal Blankenship
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1 Wednesday, October 25, 2017 Exam 2 results, key is posted on the main course website. Please check to make sure there are no errors in the scoring of the Scantron portion of the exam (note the scantron reader takes images of all forms, so you only need to alert us to errors and we can review those images). Watch for Week 8/9 Review Assessment Homework 4 will be posted by the end of the week, due on November 6.

2 Chapter 7 Circulation of the Solid Earth (very short!) Motivation - the long-term carbon cycle is tightly linked to the rock cycle, integrating the atmosphere, biosphere, oceans, and lithosphere. A VERY short overview please skim Chapter 7 for a sense of important topics. Up Next - Chapter 8 The Carbon Cycle

3 1. The melting of what component of the cryosphere has contributed most to rising sea levels in recent decades? (a) The Greenland ice sheet (b) Small glaciers and ice caps (c) The Antarctic ice sheet

4 1. The melting of what component of the cryosphere has contributed most to rising sea levels in recent decades? (a) The Greenland ice sheet (b) Small glaciers and ice caps (c) The Antarctic ice sheet

of the rise in sea levels due to melting ice on land.

5 Even though Antarctica contains early 90% of all the ice on Earth, meltwater from Antarctica has contributed less than 10% of the rise in sea levels due to melting ice on land. Most of the melting has occurred in smaller glaciers located around the globe.

6 2. Which of the following is evidence that glaciers are warming around the globe? (a) Increased calving of icebergs from the terminus of glaciers (b) Increased formation of meltwater on the surface of Greenland in summer (c) Increased depth of snow/ice in the accumulation zone (d) Increased runoff of freshwater from glaciers (e) All of the above

7 2. Which of the following is evidence that glaciers are warming around the globe? (a) Increased calving of icebergs from the terminus of glaciers (b) Increased formation of meltwater on the surface of Greenland in summer (c) Increased depth of snow/ice in the accumulation zone (d) Increased runoff of freshwater from glaciers (e) All of the above

8 Glaciers are complicated they don t just melt when Earth gets warmer. They can also accumulate snow faster at higher elevations.

9 Melting is also complex. Here, we see that a thin melt-layer forms over wide areas of Greenland every year, and this meltlayer has been getting larger as the Arctic has gotten warmer.

10 3. What important role does the cryosphere play in regulating abundances of CO 2 in the atmosphere? (a) It stores CO 2 in permafrost (b) It traps methane in permafrost and frozen clathrates (c) It enhances erosion, which returns nutrients to the biosphere (d) It alters the albedo, which impacts weather and climate, which in turn alters the growing season (e) All of the above

11 3. What important role does the cryosphere play in regulating abundances of CO 2 in the atmosphere? (a) It stores CO 2 in permafrost (b) It traps methane in permafrost and frozen clathrates (c) It enhances erosion, which returns nutrients to the biosphere (d) It alters the albedo, which impacts weather and climate, which in turn alters the growing season (e) All of the above

12 Finally, glaciers enhance erosion, increasing flow of nutrients to oceans, promoting plankton growth, hence, removal of CO 2 from atmosphere. This is an important mechanism for enhancing ice ages that have occurred many times in Earth s history. As we will discuss later, it is possible that the formation of glaciers on the Himalaya s as India collided with Eurasia was responsible for enhanced erosion and flooding of nutrients into the ocean, causing a large-scale plankton bloom for many millennia which removed enough CO 2 from the atmosphere to start the current cycle of ice ages several million years ago. This hypothesis is still being studied by geologists.

13 4. Which of the following processes takes the longest time to impact atmospheric CO 2? (a) It stores CO 2 in permafrost (b) It traps methane in permafrost and frozen clathrates (c) It enhances erosion, which returns nutrients to the biosphere (d) It alters the albedo, which impacts weather and climate, which in turn alters the growing season

14 4. Which of the following processes takes the longest time to impact atmospheric CO 2? (a) It stores CO 2 in permafrost (b) It traps methane in permafrost and frozen clathrates (c) It enhances erosion, which returns nutrients to the biosphere (d) It alters the albedo, which impacts weather and climate, which in turn alters the growing season

15 5. Which of the following processes takes the shortest time to impact atmospheric CO 2? (a) It stores CO 2 in permafrost (b) It traps methane in permafrost and frozen clathrates (c) It enhances erosion, which returns nutrients to the biosphere (d) It alters the albedo, which impacts weather and climate, which in turn alters the growing season

16 How motion creates the magnetic field and leads to continental drift Heat in the earth comes from radioactivity Fig. 7-6

17 Convection in Earth s core creates electric currents that induce magnetic fields called a dynamo. Interactions between the electric and magnetic fields result in occasional flips of the magnetic field, that is recorded in newly forming rocks Fig. 7-11

18 Magnetic field reversals appears as bands along rift zones, such as the seafloor of the Atlantic ocean. Known as seafloor spreading First detected during World War II (interfered with submarine detection)

19 From estimates of when the magnetic field reversals occurred, scientists were able to determine the age of rocks on the sea floor Fig. 7-7

20 Using earthquakes to map the continental margins Fig. 7-2

21 Waves generated by earthquakes are analogous to waves on spring (or slinky ) Compression or body waves called primary (or P) wave (like sound waves) Surface wave secondary (or S) wave (like waves on water) Fig. 7-3

22 Mapping the plate boundaries

23 Plate tectonics different kinds of plate boundaries

24 When crusts collide Fig. 7-16

25 The Rock Cycle

27 Next week - we will start looking into the details of the carbon cycle. Our main objectives will be to see if we can figure out the important sources and sinks of carbon dioxide and determine what impact human activities have on abundances of CO 2 in the atmosphere. Because there are various forms of carbon in the Earth System, the carbon cycle is complex. It also involves life, which is constantly adapting to changes in the environment. This makes our task very difficult, such that quantifying the carbon cycle remains one of the challenges of environmental sciences.

ATOC OUR CHANGING ENVIRONMENT Class 19 (Chp 6) Objectives of Today s Class: The Cryosphere [1] Components, time scales; [2] Seasonal snow

ATOC OUR CHANGING ENVIRONMENT Class 19 (Chp 6) Objectives of Today s Class: The Cryosphere [1] Components, time scales; [2] Seasonal snow ATOC 1060-002 OUR CHANGING ENVIRONMENT Class 19 (Chp 6) Objectives of Today s Class: The Cryosphere [1] Components, time scales; [2] Seasonal snow cover, permafrost, river and lake ice, ; [3]Glaciers and