eosc114-ex-reading-assignment-fall2021

EOSC114 EX Reading Assignment-Fall2021 The catastrophic Earth: natural disasters (The University of British Columbia) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university EOSC114 EX Reading Assignment-Fall2021 The catastrophic Earth: natural disasters (The University of British Columbia) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

EOSC 114 Reading Assignment, Fall 2021: Mass Extnctons/Impacts from Space (Important copyright notce) 1 Student ID: 77636835 Introducton and Goals This Reading Assignment explores global scale natural “disasters” or hazards, as well as objects that have impacted, or threaten to impact, our planet. Afer completng this assignment, you should be able to: 1. Compare the tmes and characteristcs of Earth’s fve principal extncton events. 2. Characterize the relatonship between ecosystem diversity and both extncton and originaton rates. 3. Defne “elevated extncton rates” by referring to “background extncton rates”, then interpret two estmates of “elevated extncton rates” for six diferent animal groups. 4. Use the CNEOS website to characterize near earth objects. 5. Use the Earth Impact Database to fnd and describe known craters or crater remnants on Earth. Instructons. REVIEW THESE CAREFULLY; DON’T MAKE GUESSES ABOUT YOUR TASKS 1. First skim all questons to fnd out what to expect. 2. You will need to access web resources including reports, websites and maps. 3. Some references are rather long so we will point you to specifc sectons of those readings. Citatons and access to readings will be provided within the Worksheet. 4. Complete this Worksheet during or afer reading the artcle 5. THEN, afer you have completed this Worksheet, go online to Canvas to write the Reading Assignment Quiz. a. Time available for online submission is limited. Do the reading and Worksheet BEFORE going online. b. Online questons are automatcally gradable versions of SOME of these Worksheet questons. c. Each student will get a diferent subset of these questons. 6. Important notes a. Regarding EOSC 114 Reading Assignments from past terms : This reading assignment AND the questons for the Quiz are diferent from EOSC 114 reading assignments from past terms. b. THE MOST COMMON ERROR is not reading the questons carefully. Their order may difer from the Worksheet, answer optons are randomized, AND each student gets a diferent subset of questons. Please write your Quiz carefully, with your Worksheet beside you. c. Working with peers on homework is OK, but copying the work of others is cheatng and will not help you succeed. Read UBC’s Students Code of Conduct and our strict rules regarding academic integrity at htp://www.calendar.ubc.ca/vancouver/index.cfm?tree=3,54,111,959 . d. Note there may be one or more questons about this assignment in future Quizzes or Final Exam. e. Questons in this Worksheet have checkboxes instead of numbers to avoid confusion with the numbering system in the Reading Assignment Quiz. f. Note that this course has students in non-science and science disciplines, frst and fourth year-levels and everyone in between. Some tasks may seem “easy” for some students but will be challenging for others. 1. 1 This Worksheet copyright © 2019, F. Jones, L. Porrit and UBC. All rights reserved. Re-distributon to anyone or the web is against copyright law. See UBC intellectual property rights at htps://copyright.ubc.ca/guidelines-and-resources/faq/ Page 1 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

 From this fgure, for roughly what proporton of Earth’s entre history did non-avian dinosaurs exist on Earth?  ______ 3% – 4%  ______ 8% – 10%  ______ 15% – 20%  ______ 25% – 30%  ______ 45% – 55%  ______ 65% – 75%  ______ 85% – 95% Wikipedia is not always a great resource, although in fact it has good basic coverage of extnctons startng at htps://en.wikipedia.org/wiki/Extncton_event . You do not have read all of the artcle – we will start by using just the data in the table labelled “List of extncton events“, htps://en.wikipedia.org/wiki/List_of_extncton_events .  In total, how many extncton events are listed in that table? Answer with a number , NOT a word (e.g. ‘10’, not ‘ten’). ____25_____  Below is a list of possible causes of extnctons that have been identfed. Put these causes into order with “1” being MOST commonly identfed and “3” being LEAST commonly identfed. (If you need more informaton on one of the possible causes identfed in the table, look it up!)  __3____ Impacts or “craters”  __2____ Changes in sea level, ocean chemistry or anoxia (not including “climate change” without sea-level changes)  __1____ Volcanic, food basalt, magmatc provinces or “traps” events  What type of evidence is used to identfy “extncton events”? HINT: This is NOT about evidence for how it happened but whether an “extncton event” occurred.  Climate records (or proxies for climate variaton)  The fossil record  Astronomical informaton such as evidence for supernovae, gamma ray bursts. etc.  Geological evidence of volcanic events  Geological evidence of impactors (asteroid or meteorite collisions with Earth)  How many of all the extncton events (NOTE: The Great Oxygenaton is not an extncton event.) in the table have at least one possible cause identfed WITHOUT a reference or citaton for that cause? Answer with a number , NOT a word (e.g. ‘10’, not ‘ten’). _____4_____ Read the frst four (4) paragraphs under “Causes”, then fll in blanks to complete the sentences. Note carefully when authors are discussing rates of extncton (or originaton) as opposed to extncton events.  Rather than atributng widespread and rapid decrease in the biodiversity to a single cause, at least two types of causes seem to be necessary, each possibly including many factors. The frst cause, long-term pressures on the ecosystem, called a press (one word only) by Arens and West, 2006 , make an ecosystem vulnerable. Then the second cause, a diferent set of more sudden changes, called a pulse (one word only), appears to tp the system into collapse. Now consider the apparent relatonship between ecosystem diversity and the rates at which species either appear or disappear (i.e. rates of originaton or extncton). Choose the appropriate term from within the brackets to make the following 2 sets of statements TRUE.  According to this short secton, periods with more diverse ecosystems appear to be correlated with [ increasing / decreasing / unchanging ] rates at which species disappear . Also, periods with less diverse ecosystems appear to be correlated with [ increasing / decreasing / unchanging ] rates at which species appear . Page 3 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

 If the past 100,000 years has seen highly diverse ecosystems, this relatonship would predict that the rate at which species [ appear / disappear ] might increase during this period, while the rate at which species [ appear / disappear ] might decrease. Do these predictons appear to be consistent with reality (WITHOUT trying to atribute any causes, whether human or otherwise)? [ Yes / No / Uncertain ] For the following queston, refer to this website to learn more about “peer-reviewed” artcles or references: htps://library.sdsu.edu/reference/news/what-does-peer-review-mean  In those 4 paragraphs, the authors included a total of __ 13__ references, and __ 7___ of those references appear to be peer-reviewed. Fill in the blanks with a number , NOT a word (e.g. ‘10’, not ‘ten’). Figures 2a and 2b to the right are from the Wikipedia page you accessed above and presented here with x-axes aligned. Consider what’s shown carefully. One graph shows the proporton of total marine genera 2 becoming extnct over tme, and the other shows the total numbers of marine genera over tme.  For which of the big 5 extncton events did the highest relatve proporton (i.e. percentage) of marine animal g enera (see footnote) become extnct?  O – S  Late D  P – Tr  Tr – J  K – Pg  For which of the big 5 extncton events did the lowest relatve proporton (i.e. percentage) of marine animal genera become extnct?  O – S  Late D  P – Tr  Tr – J  K – Pg  For which of the big 5 extncton events was the total number of genera the smallest just before the extncton?  O – S  Late D  P – Tr  Tr – J  K – Pg  What general lesson can be learned from this pair of fgures by examining trends rather than the spikes representng extncton events? Earlier in tme there seems to have been ______.  higher diversity, and higher proportons of that diversity sufered in extnctons.  higher diversity, and lower proportons of that diversity sufered in extnctons.  lower diversity, and higher proportons of that diversity sufered in extnctons.  lower diversity, and lower proportons of that diversity sufered in extnctons. 2 “Genera” is the plural of “genus”, and most genera include several species. Page 4 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

the animal group with the most elevated rate of extncton seems to be mammals while the conservatve model suggests that amphibians has the most elevated rate of extncton.  mammals  conservatve  reptles  highly conservatve  amphibians  One point of the artcle is to identfy that, regardless of tme period or model used, all these animal groups have been observed to be experiencing extncton rates that are ______ background extncton rates.  much less than  slightly less than  similar to  slightly more than  much more than  The conclusion is illustrated in a third way by showing the proporton of all animals in each group that have gone extnct since 1500, estmated using the two models. This is shown (in) ______ of the artcle.  Table 1  Table 2  Figure 1  Figure 2  within the text only What goes into generatng estmates and drawing conclusions like this? Is this an “easy” job? Fill in each of these blanks with just a NUMBER. No words – just one number for each blank.  The research was clearly a “team efort” as the artcle (published in the year ___2015___) has ___6___ authors, representng a total of ___3___ departments in ___8__ 5 _ diferent insttutons from ___2___ diferent countries (see footnote on frst page of the artcle). As evidence of the extensive precedent underlying this work there were __33__ references or notes, with ___3___ of these each having well over 50 contributng authors, and some details were provided as “supplementary materials” consistng of ___2___ additonal tables. Step 3: Consider just one of the possible contributors to mass extnctons: meteor or asteroid impacts.  Visit the website for NASA’s Center for Near Earth Object Studies (CNEOS) at htp://cneos.jpl.nasa.gov/ To ensure you learn and understand the terminology used, refer to the glossary (under the “Extras” menu) for help in matching the terms on the column on the lef to the defnitons on the column on the right. Term Defniton LD = __e_ A. absolute visual magnitude (which, counterintuitvely, is a smaller value for larger objects) Au = __d__ B. a measure of the proporton of light refected of a surface H = __a__ C. any object that will pass near Earth PHA = __f__ D. average distance between Earth and Sun NEO = __c__ E. average separaton between Earth and Moon Albedo = __b__ F. an asteroid deemed to possibly be dangerous Page 6 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

Now we will use the CNEOS data set to explore antcipated dates and closest approach distances of large NEOs. Click on the “NEOs” item under the “Close Approaches” menu.  Refer to the table on this NEO Earth Close Approaches page. It has 8 column headings. Which column is currently being used to sort the rows? It is the one with a small blue “up-triangle” afer its ttle. Copy the name of that column here: __close-approach CA date____. Page 7 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

 Now use the sortng capability of this table to fnd the object that is predicted to have the closest nominal distance approach to Earth of all these entries (don’t change parameters, just re-sort the current table). What is this distance in km? ___ 7688___ (use the conversion factor of 1 LD = 384,400 km) You are now in a positon to ofer advice. Two issues to consider are (1) could this object have threatened satellites in geosynchronous orbit around Earth (which is at a distance of roughly 35,000 km from the Earth) and (2) could it have been considered “possibly hazardous” to Earth?  Based on the data, how would you respond to a queston on whether the object having the closest nominal approach could have threatened geosynchronous satellites?  The object’s Close-Approach estmate does make it a possible threat, AND it is big enough to potentally damage a satellite.  Given this object’s Close-Approach estmate, it is not a threat to geosynchronous satellites, regardless of its size.  The object’s Close-Approach estmate does make it a possible threat, but it is not big enough to potentally damage a satellite.  Not enough informaton to make this judgement.  If this Close-Approach estmate was in error by up to 15,000 km, might this object have been “possibly hazardous” to Earth?  The object will not come close enough to be a threat to Earth, even given this error in Close-Approach estmate.  The object could come close enough AND it is big enough to be “possibly hazardous” to Earth.  The object could come close enough to be a threat but is not big enough to be “possibly hazardous” to Earth.  Not enough informaton to make this judgement.  We should of course be careful to understand the uncertainty in these data. Click the “reasonably low uncertainty” link in this page’s introductory paragraph above the Table. Of several parameters contributng to uncertainty, which has the greatest efect on orbital uncertainty?  number of observatons or measurements.  amount of tme spent making these observatons  quality of the observatons (e.g. radar vs optcal)  geometry of the observatons Next we ask: have all “hazardous” objects been detected? No, not yet. However, we can determine whether ongoing searches are stll fnding objects. To learn more, go to the “Introducton” item in the CNEOS website’s “Discovery Statstcs” menu.  From paragraph 1 on that page, the NEO program estmates that they have already found over 90% of ______.  all NEOs  NEOs larger than 140 m in diameter  NEOs larger than 1 km in diameter  all NEOs with albedo greater than 20%  all visible NEOs The counts of NEO discoveries by year are summarized via links (butons) along the top of this “Discovery Statstcs” Introducton page. First click the “ by Survey (km) ” buton; you should now see a graph that looks like the one shown on the right. (HINT: fnd values requested by hovering your mouse over the graph (no clicking) to see informaton about data under the mouse pointer.) Page 9 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925

 Fill in each of these blanks with just a NUMBER. No words, no decimal places. The largest number of large (> 1 km diameter) NEOs was found in the year ___ 2000___ in which a total of ___87___ large NEOs were found. In subsequent years, counts of large NEO discoveries declined, and in the year 2016, a total of only ___7___ were found.  Now, on the “ by Survey (140 m) ” page, we can see that the largest count of newly discovered NEOs 140 m or larger was in the year ___2016___ in which a total of ___563___ new NEOs in that size range were found. In comparison, the total number of NEOs in this size range discovered in, for example, the year 2000, was __308____.  Based on these observatons, it appears as if ______.  most of both large (>1 km) and moderate (>140 m) NEOs have already been found  most of the large (>1 km) NEOs have been found, but there are many moderate (>140 m) NEOs stll to be found  there are many large (>1 km) NEOs stll to be found, but most of the moderate (>140 m) NEOs have been found  there are many large (>1 km) and moderate (>140 m) NEOs stll to be found Step 4 : We now want to consider existng evidence for impacts on our planet. We will use the Earth Impact Database maintained by the Planetary and Space Science Centre (PASSC) at the University of New Brunswick, Fredericton, New Brunswick, Canada. Go to htp://www.passc.net/AboutUs/index.html and click on “Earth Impact Database” in the lef- hand menu.  From the “About …” paragraphs, how many confrmed impact structures are in the Earth Impact Database? __ 190__  All of the following are reasons why we see so few craters on Earth compared to on the moon or on other solar- system bodies. However, which one do you think is less important than all the others? Just think logically; there is no need to read anything further to answer.  We have not yet been able to examine the entre Earth’s surface with sufcient detail.  Plate tectonics has “recycled” a large porton of surface materials.  Much of Earth’s surface has been eroded.  Much of the surface is masked by vegetaton and the accumulated soil it grows in.  Oceans are both covered in water and relatvely “young” compared to contnental materials. The Earth Impact Database can be viewed on the PASSC website with data sorted in one of three ways: by name, age or size. To answer the following, use these sortng optons, found in the “ Sorted by: ” link, on right hand end of the menu.  How many impact structures, not including unknowns, are less than 10,000 years old? __ 13____  Given this value, what is the average tme between impacts in the last 10,000 years? Approximately ___ 769___ years.  What is the average tme between impacts based on only those impactors that are less than 1,000 years old (not including unknowns)? Approximately __ 200___ years between impactors in the last 1,000 years  Given these average tmes between impacts estmated over diferent tme spans, which of these statements is most likely to be CORRECT?  The tme between impacts appears to be fairly constant.  More impactors have been hitng Earth recently than in the more distant past (impactors are arriving more frequently).  Fewer impactors have been hitng Earth recently than in the more distant past (impactors are arriving less frequently).  More impactors appear to be hitng Earth recently, but the estmates vary because older craters are harder to detect.  Fewer impactors appear to be hitng Earth recently, but the estmates vary because older craters are harder to detect.  How many impact structures do we know of that are 1 billion or more years old? ___ 14___  How many impact structures are 100 metres or less in diameter? ___ 11___ Page 10 of 11 Downloaded by Emily Park (emily.d.park618@gmail.com) lOMoARcPSD|32012925