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Chapter 10 Global Effects Lecture #21 HNRT 228 Energy and the Environment Adapted from UNM and USGS 1 Chapter 10+ Overview • • • • • • Earth as a planet The polar regions and sea ice effects The stratospheric ozone situation Another look at greenhouse gasses Climate change Global warming 2 iClicker Question Which of the following layers of the atmosphere is highest above the surface of the Earth? A Troposphere B Stratosphere C Thermosphere D Mesosphere E Ozone Layer 3 iClicker Question What is the primary ingredient of the Earth's atmosphere? A Nitrogen B Oxygen C Nitrogen and oxygen in equal parts D Hydrogen E Carbon dioxide 4 iClicker Question In what part of the atmosphere does weather occur? A Hydrosphere B Stratosphere C Ionosphere D Troposphere E All of the above 5 iClicker Question How rapidly a planet loses its atmosphere depends on the planet's • I. mass • II. atmospheric composition • III. temperature • IV. rotation period A B C D E I & II III & IV I, II, & III II, III, & IV I, II, III, & IV 6 iClicker Question The presence of Earth’s magnetic field is a good indication that A there is a large amount of magnetic material buried near the North Pole. B there is a quantity of liquid metal swirling around in the Earth's core. C the Earth is composed largely of iron. D the Earth is completely solid. E there are condensed gasses in the core of the Earth. 7 The Earth 8 General Features Mass: MEarth = 6 x 1027 g Radius: REarth = 6378 km Density: = 5.5 g/cm3 Age: 4.6 billion years 9 Earth's Internal Structure How do we know? Earthquakes. See later Crust: thin. Much Si and Al (lots of granite). Two-thirds covered by oceans. Mantle is mostly solid, mostly basalt (Fe, Mg, Si). Cracks in mantle allow molten material to rise => volcanoes. Core temperature is ~6000 K. Metallic - mostly nickel and iron. Outer core molten, inner core solid. Atmosphere very thin 10 Earth's Atmosphere 78% Nitrogen 21% Oxygen Original atmosphere changed over time. Atmosphere today is largely due to volcanoes and life (especially plant). gas is ionized by solar radiation ozone is O3 , which absorbs solar UV efficiently, thus heating stratosphere commercial jet altitudes room temperature 11 Ionosphere Particles in the upper reaches of the atmosphere are ionized by the sun. Radio signals below ~20 MHz can “bounce” off the ionosphere allowing communication “over the horizon” 12 Convection Earth's surface heated by Sun. What would happen if it couldn't get rid of the energy as fast as it gets in? Convection also occurs when you boil water, or soup. Think of Earth's surface as a boiling pot! Convection causes both small-scale turbulence and large scale circulation patterns. It also occurs within Earth, on other planets, and in stars. 13 The Greenhouse Effect Main greenhouse gases are H2O and CO2 . If no greenhouse effect, surface would be 40 oC cooler! 14 iClicker Question: The dinosaurs were most likely wiped out by: A: disease B: hunting to extinction by cavemen C: a giant meteor impact D: the close passage of another star 15 iClicker Question: A leading cause of Global Warming is: A: Increased soot (smog) in the atmosphere. B: Increased carbon dioxide in the atmosphere. C: The Earth is getting closer to the sun. D: The luminosity of the sun is steadily increasing. 16 iClicker Question: The Greenhouse effect would not occur if: A: The Earth had no atmosphere. B: The amount of carbon dioxide doubled. C: We got rid of all the forests. D: The Earth didn’t have an ocean. 17 Pollution C + O2 Global Warming: The Greatest Threat © 2006 Deborah L. Williams (Combustion) CO2 Burning carbon-containing fossil fuels produces carbon dioxide. 18 CO2: Most Significant Greenhouse Gas Global Warming: The Greatest Threat © 2006 Deborah L. Williams Humans have increased carbon dioxide (CO2) in the atmosphere by more than 35% since the Industrial Revolution. CO2 CH4 (National Oceanic and Atmospheric Administration 2006) The most carbon dioxide in 650,000 years. (IPCC 2007) Jennifer Allen graphic Source: ACIA 2004 19 Temperature Measurements “Warming of the climate system is UNEQUIVOCAL” (IPCC 2007) Top 11 warmest years on record have all occurred in the last 12 years. (IPCC 2007) 2006 warmest year on record in continental US. (NOAA 1/07) 20 Alaska as Ground Zero for Warming Surface Air Temperature Trends 1942-2003 In past 50 years, Global Warming: The Greatest Threat © 2006 Deborah L. Williams Alaska: Temperatures have increased • 4oF overall (National Assessment Synthesis Team) Worldwide: Temperatures have increased • Slightly more than 1oF (IPCC 2007) Chapman and Walsh, 2004 21 Why has Alaska warmed the most? Global Warming: The Greatest Threat © 2006 Deborah L. Williams The Albedo Effect Snow and sea ice reflect 85-90% of sun’s energy. Increased melting of snow and sea ice Ocean surface and dark soil reflect only 10-20%. Land or water warms faster More dark earth and ocean surface is exposed (ACIA 2004) More of sun’s heat energy is absorbed “White shirt versus Black shirt” 22 Impacts in Alaska 1. Melting Melting Sea Ice An area twice the size of Texas has melted away since 1979 (over 20% decrease). (National Ice 40% thinner. (Rothrock,D.A, et al. 1999) Source ACIA, 2004 Jennifer Allen Animation Arctic Sea Ice Extent (millions of sq. km.) Global Warming: The Greatest Threat © 2006 Deborah L. Williams Snow and Ice Data Center 2005) 9 - 8 - 7 - 6 - (NOAA FAQ 2007). ARCTIC SEA ICE AREA 1979-2005 Source: NSIDC, 2005 1978 Ice only 6 – 9 feet thick at North Pole | 1983 1988 | 1993 | 1998 | 2003 | 2005 Northwest passage opened Aug 21, 2007 23 Impacts in Alaska Melting Sea Ice 1. Melting Arctic Ocean could be ice free in summer by 2040 Global Warming: The Greatest Threat © 2006 Deborah L. Williams (U.S National Center for Atmospheric Research 2006). “Our research indicates that society can still minimize the impacts on Arctic ice.” Dr. Marika Holland, National Center for Atmospheric Research 2000 2040 24 Impact World-wide Global Warming: The Greatest Threat © 2006 Deborah L. Williams Impact on Ski Industry 1. Melting • • • • • • In the US skiing is a $5B industry 2006 saw a 78% decline in skiers visiting the pacific northwest US Ski Seasons have shortened by 1 day/year for the last 20 years Many European ski resorts below 1800 m (6000 ft) will close 50 to 90% of Alpine glaciers will be gone by 2100 Some resort to snowmaking • Expensive • Requires lots of water • Requires lots of energy • In New Mexico, many ski areas can’t open until after Xmas 25 Impacts in Alaska The rapid retreat of Alaska’s glaciers represents about 50% of the estimated mass loss by glaciers through 2004 worldwide. (ACIA 2004) McCall Glacier Glacier Bay (Riggs Glacier) 1941 1958 Austin Post photo Glacial Retreat 1. Melting USGS photo Loss of over 588 billion cubic yards between ’61 and ’98. (Climate Change Alaska’s glaciers are responsible for at least 9% of the global sea level rise in the past century. (ACIA 2004) 2004 2003 att Nolan photo 11/05) Bruce Molnia photo 26 Melting of the Greenland Ice Sheet • • • • • According to NASA scientists, the Greenland ice sheet is melting faster than it is being replaced, contributing to sea level rise The loss of ice from Greenland doubled between 1996 and 2005 From 1996 to 2000, the largest acceleration and mass loss came from southeast Greenland From 2000 to 2005, the trend extended to include central east and west Greenland It is estimated that 69 per cent of the ice-mass loss in recent years came from eastern Greenland 27 Greenland ice is declining faster than expected • • • Between 2003 and 2005 the low coastal areas of Greenland lost 155 gigatons of ice per year due to excess melting while the high elevation interior gained 54 gigatons annually from excess snowfall Between 2004 and 2006, the rate of melting accelerated, with the massive ice sheet melting two and one-half times faster than the previous two-year period Greenland lost roughly 164 cubic miles of ice from April 2004 to April 2006—more than the volume of the North American Great Lake Erie 28 Greenland Ice Sheet Dramatic ice mass losses concentrated in the lowelevation coastal regions, with nearly half of the loss coming from southeast Greenland NASA Earth Observatory 29 Greenland Ice Sheet Greenland is now losing 20 percent more mass than it receives from new snowfall each year. NASA Earth Observatory 30 Greenland Ice Sheet University of Colorado, CIRES 31 Melting of ice in Greenland 2001-2003: A significant increase in the melting area has been observed along the edge of the ice cap in Greenland. NASA Earth Observatory 32 Retreat of Ice and Snow in Greenland Ice loses in Greenland range from 5 to 25 centimeters of water equivalent per year NASA Earth Observatory 33 Calving of Helheim Glacier, Greenland The glacier’s peak rate of flow has increased from 8 km/yr in 2000 to 11 km/yr in 2005 Helheim glacier, located in southeast Greenland, is now one of the fastest moving glaciers in the world 1986-2006: These images show the retreat of Helheim glacier’s calving front This May 2005 picture of Helheim Glacier, demonstrates high calving activity associated with faster glacial flow 34 Dramatic changes in Arctic Sea Ice Imagine an icefree Arctic 35 Evidence of extensive snowmelts in West Antarctica • • January 2005: Areas of extensive snowmelt (shown in yellow and red) have been discovered by a team of NASA and university scientists in response to warmer temperatures in west Antarctica . The combined area affected is as big as California. NASA Jet Propulsion Laboratory 36 Breakup of Larsen ice shelf (Antarctic Peninsula) 220 metres thick Larsen B shelf existed for at least 400 years prior to breakup 37 Disintegration of the Larsen B Ice Shelf, Antarctic Peninsula The ice shelf disintegrated suddenly in March 2002 due to warm summer temperatures NASA Earth Observatory 38 Breakup of Antarctica’s Ross Ice Shelf • • An iceberg (B-15J) of size of a small United States state cracked off the Antarctica’s Ross Ice Shelf in March 2000 On February 1, 2007, three new icebergs were formed due to the break up of the original iceberg NASA Earth Observatory 39 Breaking Off Filchner Ice Shelf Antarctica Filchner Ice Shelf is the largest ice shelf on the planet In 1986 the front edge of Ice Shelf broke off into three enormous icebergs 40 Calving of Ninnis Glacier Antarctica 22 January 2000: The Ninnis Glacier Tongue soon after the initial calving 5 February 2002: Iceberg split into two sections and started moving away from Ninnis Glacier 41 Cracks on Drygalski Ice Tongue Antarctica The ice tongue was discovered in 1902 21 February 2005: Drygalski calved an iceberg Image shows cracks formed by time and ocean currents 42 Shrinking Lake Chad shared by Nigeria, Niger, Chad and Cameroon Persistent drought has shrunk the lake to about a tenth of its former size • 1972: Larger lake surface area is visible in this image • 2001: Due to regionally drying climate and human demand for fresh water, Lake Chad is fraction of what is once was • 2004: In many places, the green of wetlands is being replaced by drifting sand dunes (tan ripples mixed with green) 43 Shrinking Breidamerkurjökull Glacier Iceland • 1973-2000: Images show glacier has receded and the glacial lake at its tip has enlarged 44 Ayles Ice Shelf, Ellesmere Island, Canada • 1986: Images show Degradation of forest area • 2001: Between 1984 and 1999, 38 per cent of forests were degraded Ayles Ice Shelf on Ellesmere Island, broke free on August 13, 2005 and drifted out to the sea NASA Earth Observatory 45 Disappearing Icecap of Mt. Kilimanjaro, Tanzania Africa’s highest mountain with a forest belt having rich diversity of ecosystems • 1976: Glaciers covered most of the summit • 2000: The glaciers had receded alarmingly 46 Retreat of Gangotri Glacier, India • • Gangotri glacier has retreated more than 850 meters, in the last 25 years It has retreated more than 76 meters from 1996 to 1999 NASA Earth Observatory 47 Glacial Lakes and Glacial Lake Outburst Floods Glacial Lakes in the Bhutan-Himalaya Region • • • Jeffrey Kargel, USGS/NASA JPL/AGU Glacial lakes are formed due to the melting of ice and snow from glaciers Due to the faster rate of melting from the glaciers, possibly due to global warming, water is accumulating at an increasing rate in these lakes Sudden outburst results in Glacial Lake Outburst Flood (GLOF) downstream causing destruction of life and property 48 Retreat of Upsala Glacier, Argentina January 2004 position The Upsala glacier has retreated more than 4 kilometers since late 1960’s to mid 1990’s and continues to retreat NASA Earth Observatory 49 Retreat of San Quintin Glacier, Chile The San Quintin Glacier appears to be losing mass and retreating NASA Earth Observatory 50 Impacts in Alaska Animals at Risk 3. Animals Polar bears Walruses Ice seals Black guillemots Kittiwakes Salmon Caribou Arctic grayling Rising temperatures Shrinking habitat Food harder to get Expanding diseases Competition 51 Inundation Sea level has increased 3.1 mm/year between 1993 and 2003 (IPCC 2007). This is 10-20 times faster than during the last 3,000 years (ACIA 2004). 0.4-0.6 meters of sea level rise by 2100 if 3 times preindustrial CO2 or 1% increase/year (Overpeck et al. 2006). 52 Inundation Inundation from Four Meter Sea Level Rise (or, 1m rise Weiss and Overpeck, 2006 + 3m storm surge) 53 What We Can Do R E D U C E CO 2 EMISSIONS 1. Is it Achievable? 2. Action Is Possible at Every • • • • • • Individual Corporate Local State Federal International 3. Some Steps Photo courtesy of 7summits.com Global Warming: The Greatest Threat © 2006 Deborah L. Williams Level 54 Global Warming: The Greatest Threat © 2006 Deborah L. Williams What We Can Do Wind Power 55 Measuring Your Carbon Footprint Major Carbon Contributors: Electric Consumption Gas/Heating Oil Consumption Car and Miles Driven Miles Flown Recreational Vehicle Use Average Footprint is 30,000 pounds 56 Conservation: Three Examples What We Can Do Unplug Appliances Vampires! 43 billion kWH lost/year in US Est: 1,000 lbs/year/person Pump Up Tires 4 million gallon of gas wasted daily in US Extends life of tires by 25% Est: 1,000 lbs/year/person Lower Thermostat 2 degrees Est: 2000 lbs/year/person 57 Energy Efficiency: Two Examples Compact Fluorescents Four to six times more efficient Est: for each bulb converted, save about 100 lbs/year Bus/Walk/Bike Save money on fuel and maintenance Est: 5,000 lbs/year 58 Earthquakes They are vibrations in the solid Earth, or seismic waves. Two kinds go through Earth, P-waves ("primary") and S-waves ("secondary"): 59 How do they measure where Earthquakes are centered? seismic stations * * * 60 Like all waves, seismic waves bend when they encounter changes in density. If density change is gradual, wave path is curved. S-waves are unable to travel in liquid. Thus, measurement of seismic wave gives info on density of Earth's interior and which layers are solid/molten. Zone with no S waves: must be a liquid core that stops them But faint P waves seen in shadow zone, refracting off dense inner core No P waves too: they must bend sharp at core boundary Curved paths of P and S waves: density must slowly increase with depth 61 Earth's Interior Structure Average density 5.5 g/cm3 Crust Mantle Core 3 g/cm3 5 g/cm3 11 g/cm3 Density increases with depth => "differentiation" Earth must have been molten once, allowing denser material to sink, as it started to cool and solidify. 62 Earthquakes and volcanoes are related, and also don't occur at random places. They outline plates. Plates moving at a few cm/year. "Continental drift" or "plate tectonics" 63 When plates meet... 1) Head-on collision (Himalayas) side view 2) "Subduction zone" (one slides under the other) (Andes) 3) "Rift zone" (two plates moving apart) (Mid-Atlantic Ridge, Rio Grande) 4) They may just slide past each other (San Andreas Fault) => mountain ranges, trenches, earthquakes, volcanoes top view 64 iClicker Question: Sunlight absorbed by the Earth’s surface is reemitted in the form of? A: radio waves B: infrared radiation C: visible radiation D: ultraviolet radiation E: X-ray radiation 65 iClicker Question: What steps are you willing to take to reduce your carbon dioxide footprint? A: Walk/bike/bus to work B: Unplug appliances when not in use C: Replace light bulbs with compact fluorescents D: Wash clothes in cold or warm water E: Buy a Prius 66 The Mid-Atlantic Ridge is a rift zone. 67 What causes the drift? Convection! Mantle slightly fluid and can support convection. Plates ride on top of convective cells. Lava flows through cell boundaries. Earth loses internal heat this way. Cycles take ~108 years. Plates form lithosphere (crust and solid upper mantle). Partially melted, circulating part of mantle is asthenosphere. 68 Pangaea: 200 million years ago, all the continents were close together. 69