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The third exam of GEOL1302: Introduction to Climate ChangeNote: All of the “Please choose incorrect description” questions contain correct answers in bold from lecture notes so study and memorize them as much as you can before encountering the actual incorrect description on the actual exam. 1. What is the equation for quantifying feedbacks? (a) (b) (c) (d) ∆ Tf=∆ Ti(1−g)2. Please choose incorrect description. (a) From question 1, if g=0, then there is no feedback and the final temperature change is equal to the initial temperature change. (b) From question 1, if g is between 0 and 1, then ∆ Tf is larger than∆ Ti, meaning the feedback is positive.(c) From question 1, if g is less than 0, then ∆ Tf is less than ∆ Ti, meaning the feedback is negative.3. Please choose incorrect description. (a) Total feedback parameter g for our climate can be expressed as a sum of feedback parameters from the individual feedbacks:g = gia + gwv+ gcloud+ glrwhere gia is the ice–albedo feedback, gwv is the water-vapor feedback, gcloud is the cloud feedback, and glr is the lapse-rate feedback (we consider here only the fast feedbacks). (b) water-vapor feedback = 0.6 (c) ice –albedo feedback = 0.1 (d) lapse rate feedback = − 0.34. Please choose incorrect description. (a) Summing these individual feedbacks, we get a total feedback parameter for our climate of g = 0.4 to 0.7 (b) Feedbacks amplify the warming from that due directly to greenhouse gases and other radiative forcings. (c) For this doubling of carbon dioxide, the initial warming ΔTi is 1.2°C. Using the feedback strengths implies a range of final temperature ΔTf = 2 to 4.5 °C. (d) Doubled carbon dioxide corresponds to a radiative forcing (RF) of roughly 4 W/m^2.
5. What is the climate sensitivity (the sensitivity as the warming per unit of radiative forcing)? (a) (b) (c) (d) The climate sensitivity 0.5 – 1.1 °C/ (W/m^2), with a best estimate of 0.75 °C/ (W/m^2).6. Please choose the incorrect description. (a) We have only considered fast feedbacks in our calculation of the climate sensitivity. This is probably appropriate for climate change over the next century. (b) Over the next millennium and beyond, the contribution of slow feedbacks can become important. These feedbacks are mainly positive, so the climate sensitivity may be significantly higher when we consider such longer periods. (c) A radiative forcing is an imposed change on the energy balance of the Earth; in response, the Earth changes its temperature so that energy balance is reestablished. (d) Summing all changes, we get a new radiative forcing over the past 250 years of +1.6 W/m^2.7. Please choose the incorrect description. (a) Earth’s continents are moving slowly, but over tens of millions of years, this movement, also referred to as tectonic motion, substantially alters the arrangement of the continents across the Earth’s surface. (b) The location of continents determines whether ice sheets form. (c) Ice sheets form because of cold summer temperatures. If snow that falls during the winter does not melt during the following summer. (d) Land at low latitudes is the most favorable location for cold summers (and winter snow).8. Please choose the incorrect description. (a) The loss of an ice sheet will warm the climate. (b) If Antarctica moved toward the equator over the next 100 million years, loss of the Antarctica ice sheet would be likely, thus leading to significant warming. (c) The location of the continents determines the ocean circulation. (d) The oceans carry huge amounts of heat from the tropics to the high latitudes, so changing ocean circulation can change the temperatures of the tropics and Polar Regions.9. Please choose the incorrect description. (a) Movement of the continents can change the pattern of rainfall and expose new rock to the atmosphere, which changes the locations and rate of chemical weathering – and therefore the amount of carbon dioxide in the atmosphere. (b) 40 million years ago the Indian subcontinent collide with the Asian continent, forming the Himalayas and the adjacent Tibetan Plateau.
(c) Changing wind patterns brought heavy rainfall onto the vast expanse of newly exposed rock in these features, and the resultant chemical weathering drew down atmospheric carbon dioxide over a period of tens of millions of years. (d) The movement of the continents is responsible for the rapid warming of the past few decades10. Please choose the incorrect description. (a) If the Sun brightens, the climate will warm. We might therefore wonder if the recent warming of the climate can be explained by an increase in the output of the Sun. (b) The Sun’s output varies on many time scales. Over the Sun’s 5-billion- year life is has slowly gotten 30%. (c) Since the late 1970, instruments on satellites have been measuring the solar constant, over this period, the most significant observed variation is an 11year cycle, by which total solar energy output varies approximately 0.1 percent. (d) The climate does not respond to these 11-year variations because of the enormous thermal inertia of the oceans11. Please choose the incorrect description. (a) The rapid warming of the past few decades is not caused by a brightening of the Sun. (b) The Sun has brightened over the past few hundred years and this can potentially explain at least some of the gradual warming of the 18th, 19th and early 20th centuries. (c) This has led to a positive radiative forcing with a magnitude of approximately +0.12 W/m2, which is minor compared to radiative forcing from greenhouse gases. (d) If the Earth moved closer to the Sun, then the solar constant would increase even if the brightness of the Sun did not change.12. Please choose the incorrect description. (a) Over the course of 100,000 years or so, as the orbit becomes more eccentric, the average Earth-Sun distance increases and the average amount of solar energy falling on the Earth decreases. (b) For the Earth’s orbit, the change in eccentricity causes the annual average solar constant to vary by approximately 0.5 W/m^2. This change in the solar constant will lead to changes in the Earth’s climate. (c) Today, the Earth is closest to the Sun during July, when it is wintertime in the northern hemisphere. (d) In 11,500 years, the Earth will be closest during July, and in 23,000 years it will again be January.13. Please choose the incorrect description.
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School: University of Houston
Course: Intro to Global Climate Change
Professor: Yunsoo Choi
Term: Fall 2016
Name: GEOL 1302, Exam 3 Study Guide
Description: Covers most of Chapters 7 and 8 and a little bit from Chapter 6