Geog 101, Week 3
Geog 101, Week 3 101
California State University Northridge
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This 2 page Class Notes was uploaded by Francesca Notetaker on Sunday October 2, 2016. The Class Notes belongs to 101 at California State University Northridge taught by Mia Dittmer in Fall 2016. Since its upload, it has received 18 views. For similar materials see Geog 101 in Geography at California State University Northridge.
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Date Created: 10/02/16
Week 3 – 09/23 (starting from section V, letter C) V. C. Evaluating causes of increasing carbon dioxide and our warming climate 1. Is the current global warming trend owing to natural or human causes—or both? 1. Increase in solar output Evaluation: false Proof: Atmosphere signature (temperature trends wise in the atmosphere- what we would expect to see is an increase in lower atmosphere). We should also see an increase in the upper atmosphere as well and this is the sticking point, we're not observing that at all. Today's temperature trends: we have an increase temperature in the lower atmosphere and a decrease in temperature in the upper atmosphere. 2. Volcanic activity is causing the warming Evaluation: false Today: explosive volcanoes (launch dust and ash in the atmosphere - it would cool the temperature down) Atmosphere signature: -we would expect to see a decrease in surface temperature -increase temperature in upper atmosphere 3. The oceans are causing the increase in carbon dioxide Evaluation: False First proof: carbon12 ratio -c13:c12 what we have been observing is a decrease in c13 and c12 ratio. What is changing the ratio is the increasing c12. Oceans release the same amount of c13 and c12 in the atmosphere. Burning fossil fuels is the only thing that increases the c12 levels in the atmosphere. Second proof: Today: the oceans are becoming more acidic (they are taking in carbon dioxide) Carbon dioxide + water= carbonic acid 4. It's just natural climatic variability Untruthful statement. First proof: the Earth has had 6 previous warm periods (interglacials) in this case we've looked at these previous interglacials and we measured how much carbon dioxide levels were associated to these warm periods. Of the six, not one of these warm periods saw carbon dioxide levels exceeding 300 parts per million. Today: 402 parts per million. Second proof: natural trends in climate. Natural variation in climate takes thousands of years to enter and exit. Interglacials are temporary, often times you go back to a glacial period. Today's warming trend: rapid onset. Ex.: we wanted to find the fastest natural carbon dioxide increase in the ice core record - 20 parts per million in 1,000 years. 12 thousand years ago. Today's carbon dioxide concentrations have increased 20 parts per million in the last 11 years. Enhanced by human activity. V. D. Effects of global warming: 1. Temperatures are going to increase. Warming is estimated to rise anywhere between 3.2 to 7.8 degrees F by 2100 (prediction). Real: between (1880-2014) an increase of 1.4 degrees F Ice begins to melt, mostly polar ice sheets begin to melt. Arctic sea ice has decreased in winter thickness by 40% in the last 40 years. We feel that the arctic summer months will be ice-free be as soon as 2140 or even sooner. Side effects: more absorbion of sunshine will warm the oceans rapidly = warmer atmosphere. it accelerates as we warm the water we accelerate melting. 2. Ice sheets are warming up the ocean. 3. Melting of land ice will cause sea levels to rise. It will force migration ans it will happen slow. 8 inches since 1900 (CA coast). It will rise 7-23 inches up to 6 feet by 2100.
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