OCN 105 Exam 2022/2023 with 100% correct answers

Origin of Earth Jan 1 Moon formation Jan 8 Earliest bacteria/algae April 5 Buildup of free oxygen in atmosphere May 31 Earliest fish Nov 23 Frist Dinosaur Dec 14 Dinosaur extinct Dec 26 Early horses Dec 27 Early primates Dec 27 Modern man Dec 31 Keeling curve -showing atmospheric carbon dioxide level increase at faster rate each year -long term trend -annual cycle measuring CO2 since 1958 understanding patterns in past climate records is essential for demystifying environmental history -timer series analysis looks for basic characteristics -trends, periodicity, outliers, abrupt changes, changes in variance in-phase both time series increase and decrease simultaneously periodically happens on a fixed schedule or intervals anti-phase Top time series exhibits a peak, the bottom time series exhibits a low peak increasing variability no serious extreme trend but increase in value over years Earth in long-term cooling trend for 50 million years ago amplitude of climate fluctuations has increased. When? and how get data? -beginning around 6 million years ago -obtain through ocean massive climate changes were driven by tectonics Amasia next super continent cooling lead to drying -forests shrank -grasslands expanded savannah open tropical ecosystems composed of grasses and sedges open tropical ecosystems composed of grasses and sedges two major trends in global climate over past 50 million years -overall decrease in temperature -larger degree of climate fluctuation over time Three possible outcomes of population evolution in response to environmental dynamics -move and track habitat change geographically -adapt by genetic change and select structures and behaviors that can be used to cope with new habitat -became extinct due to inability to relocate to favored habitat primate population came down out of the trees and encountered new selection pressures of the savanna evolutionary pressure in African savannah -need to move greater distance across the more open landscape -greater risk of predation and harder time finding adequate food pressure selected hominin walking upright and having bigger brains Savanna hypothesis long-term trend towards increase aridity and the expansion of the savanna was major driver of hominin evolution Lake Turkana -worlds largest permanent desert lake -wave-cut notches higher up from lakes shore -rounded pebbles reflecting wave washing -most fossil record of early humans Homo erectus 1.9 and 1.6 million years ago appeared Australopithecus afarensis vanished and group Paranthropus and Homo appeared connected with climate swings Hominins evolve ability to respond to shifting environmental conditions varied diets Variability Selection Hypothesis -events in human evolution were shaped not by any single type of habitat or environmental trend but rather by environmental instability study of fossil and environmental records forms two leading hypothesis for human evolution -savanna hypothesis -variability selection hypothesis ice age became more pronounced about 1 million years ago last glacial period 115,000 to 14,000 years ago last glacial maximum 21,000 years ago During last ice age -North America became fully covered by 2 mile-thick sheet of ice -global climate cooler and drier ice age record obtained from chemical signals stored in sediments from the bottom of the ocean most water to build ice sheets come from ocean bering strait -50 miles from Siberia to Alaskas -se level 120m lower rate of global Sea level since last glacial maximum 6mm/yr thermal expansion (steric SLR) ocean temperature increases, ocean density decreases -ocean water expands and sea level rise melting of glaciers and polar ice sheets ocean gain fresh water from land mass increases and level rises glacial isostatic adjustments rebound of the Earth from Last Glacial Maximum causes some land surfaces to rise and some ocean bottoms to fall land water storage changes human-induced groundwater depletion and wetland destruction adds fresh water to the oceans main cause of global sea level rise since 1970 -melting ice sheets -thermal expansion greenhouse gas emissions remain at high level likely average global mean SLR rate between will be 8-16 mm/yr for most 20th century believed first American were Clovis hunters who followed mammoths and other prey through an open corridor between two massive Canadian ice sheets 1197 archaeologists discovered human evidence of human occupation dating to more than 14,000 years ago, thousand years before the Clovis hunters appeared in North America Beringian standstill -Humans settled in Beringia from about 25,000 to 15,000 years ago -Long period of time allowed them to develop unique traits and adaptations, differentiating them from their Asian ancestors Kelp route humans migrated south along the west coast of Canada, surviving on rich coastal resources new genetic research shows single migration waves to the Americas no earlier than 23,000 years Aho Megafauna extinction tale of sustainability in changing climate when climate changes impose stresses on populations if practice adopted by them are not sustainable lead to extinction Ice age (AKA Pleistocene) started around 2.6 million years ago -ended 11,7000 years ago most recent glacial period -2 mile-thick ice sheets in northern hemisohere northern hemisphere -lot cooler than today -cause extensivevegetation changes big mammals on animal to survive harsh environment mammals lived in vast territory maximum extension of Mammuthus primigenius during the Late Pleistocene based on the current fossil record modern elephant has big ears more effectively dissipate heat off to environment mammoth -have small ears that covered in wool -one-tenth the size ears of those of an American elephant of similar age -lived in cold desert-like environment African elephant lives in hot and dry environment Asian elephant lives in cool and wet environment how mammoth conserve heat -subcutaneous fat for insulation -thick hair -specialized blood circulation -small ears -large size climate change killed holly mammoth -climate warmed quickly at end ice age -got lot warmer and mammoths didn't have mechanism to dissipate heat off mammoth eat -forbs, hig in protein -grazing, maintained by megafauna herbs and their manure fertilized how do we obtain what they ate -DNA analysis of plants preserved in the permafrost during the ice age -Analysis of the stomach Large animals likely found it difficult to survive each time climate warmed Human presence could have had a major and negative impact on megafaunal adaptation processes during the repeated phases of sudden climate changes human hunter reduced population of mammoth Lone survivor -mammoth of St. Paul, Alaska -survived about 5,600 years ago Paleo environment proxies indicate decrease in freshwater availability leading to time of extinction overkill theory human hunter responsible for extinction of megafauna in northern Eurasia and North and South America after last Ice Age agriculture developed independently in many regions of the world -Africa: millet -Asia: Rice why agriculture develop in different parts of the world -over population -climate change how climate change allow agriculture grow different parts world -farming impossible in ice age -everything on earth had to change behaviors -more plants and animals which allowed people settle down how agriculture made possible -got lot warmer and wetter -climate became more stable Holocene -climate warmer -more stable -more CO2 Greenland -Thickness about 2 km and over 3 km at its thickest point -Ice old as 110,000 years GISP2 Drill Dome -digs into ice cores -small atmosphere of bubbles trapped into ice 22 degree F spike able to develop and observe ice cores higher CO2 levels -favored photosynthesis -increase crop yield stable climate reliability of harvests ice cores tell us about concentrations of CO2 and CH4 in the atmosphere greenhouse gases exist in very small quantities in atmosphere CO2 and CH4 are highest -during warmer interval -interglacial deforestation -trees remove CO2 from the atmosphere -removing trees acts to increase CO2 in atmosphere rice agriculture -rice paddies contain organic matter in decomposition -process produce CH4 anthropocene human activities started having significant global impact on Earths geology and ecosystems Anasazi civilization of Native Americans that thrived in the American Southwest from roughly 750 to 1150 Mesa Verde National Park -located southwest Colorado -in 1200s the Anasazi built dwellings into the side of the mesa, including this one known as Cliff Palace Cano Canyon and Mesa verde -abandoned in the 12th and 13th century CE -migration possibly triggered by drought how do know droughts happened in past tree rings dendrochronology -study tree rings -operate on principle that in temperate climates trees grow one ring every year tree-ring dating -cross section or obtain core -tell us about the spatial extent of past droughts -shows long period of drought over the western US Methuselah 4,847 year old bristlecone pine tree growing high in the white mountains in eastern California Kauri trees -measure 4 meter wide -live up to 2,000 years mega drought time of extreme dryness Anasazi cultivation -based on corn, squash, and beans -maize southwest Anasazi farmed -captured rainfall runoff time when most rainfall is in North America -summer -North American monsoon Driver of Anasazi villagers to leave -climate change -religion -warfare -monsoon more reliable drought -Society became more dependent on agriculture -Great drought hit around 1276 -Increase violence and warfare Dandy horse -Failure crops caused price oats to double than quadruple and etc. -Mechanical horse that didn't need to be fed impact on North America -June 6, snow fell in Albany, New York, and Dennysville, Maine -In July and August, lake and river ice was observed as far south as northwestern Pennsylvania 1816 was agricultural disaster -crops declined drastically most powerful eruption in recorded history -Tambora, in Indonesia not as big compared with ancient eruptions -Wah Wah Springs -yellowstone volcanic climate effect -sulfur goes travel 15 miles up into stratosphere -create bog -unleash volcanic winter sulfur in atmosphere create redder sunsets Why do large volcanic eruptions cool Earth's climate? sulfuric gases combine with water vapor Painting created during times of volcanic eruptions Krakatau volcano Anak Krakatau erupts before the 2018 Indonesia tsunami caused collapse of volcano due to eruption which triggered a tsunami climate impacts of volcanic eruptions relatively shortly lived sulfuric acid aerosol particles fall down from stratosphere Little Ice Age centuries-long period of global coolin Little Ice Age- Big chill -dropped four degrees colder -expose medieval weakness -lots of significant extremes Little Ice Age (LIA) was just a cold blip during Holocene coldest period during past millennium drop 5 degree temperature -drops crop yield by 10% -people who make other stuff become unemployed climate change not trigger but add to the storm and turmoil caused little ice age -less sun spots -more volcanic ash medieval warm period -agriculture spreads -wine exported to France What is causing the warming today increase in man-made CO2