Global Warming Is HumanInduced Climate Change Going To

Global Warming Is Human-Induced Climate Change Going To Destroy The World? Ok… that’s a bit dramatic. But, good questions are: 1) What is the evidence for recent climate change? 2) Do we need to worry about it – what are the consequences? 3) What can we do about it? Data and diagrams from Richard Deem, Michael Mann, Lee Kump and the Intergovermental Panel on Climate Change

History of Earth’s Atmosphere/Climate • Earth formed ~4. 6 billion years ago • Originally very hot, probably molten, early impact forming the moon • Any early atmosphere removed by initiation of sun’s fusion reactions and solar wind • Granitic crust and liquid water was present by ~4. 3 billion years ago (zircon dating) • However, much of Earth’s early history was erased during late heavy bombardment (~3. 9 billion years ago)

History of Earth’s Atmosphere/Climate • First life appeared by ~3. 8 Ga • Photosynthesis began 3. 5 -2. 5 Ga, clear evidence for significant oxygen in the atmosphere by 2. 0 Ga • Photosynthesis introduced oxygen and removed carbon dioxide and methane (greenhouse gases) • Earth began current cycles of glacial and interglacial periods ~3 Ma

Solar Energy Sun Solar Energy Earth’s Temperature

Earth’s Temperature Sun Solar Energy Radiative Cooling

Sun Greenhouse Effect

Earth’s Atmospheric Gases Nitrogen (N 2) Oxygen (O 2) Water (H 2 O) Carbon Dioxide (CO 2) Methane (CH 4) 99% Non. Greenhouse Gases 1% Greenhouse Gases

Sun Runaway Greenhouse Effect • 97% CO 2 • 3% N 2 • Water & sulfuric acid clouds • Temperature: 860°F (hotter than Mercury which is nearest to the sun) Venus

CO 2 (ppm) 420 Carbon Dioxide Levels CO 2 (ppm) 370 320 Muana Loa Readings CO 2 Levels Since 1958 370 350 330 310 40 30 20 10 0 270 220 Dome Concordia 170 600000 Vostok Ice Core 400000 200000 Time (YBP) 0

Carbon (109 metric tons) Worldwide Carbon Emissions 8 7 6 5 Total Liquid fuel Solid fuel Gas fuel 4 3 2 1 0 1750 1800 1850 1900 Year 1950 2000

Carbon (109 metric tons) 8 Annual Carbon Emissions 6 Annual carbon emissions Atmospheric CO 2 average 4 2 0 1955 1965 1975 1985 Year 1995 2005

Future Atmospheric CO 2 Levels? • Increasing CO 2 emissions, especially in China and developing countries • Likely to double within 150 years: • Increased coal usage • Increased natural gas usage • Decreased petroleum usage (increased cost and decreasing supply)

Kyoto Protocol • Adopted in 1997 • Cut CO 2 emissions by 5% from 1990 levels for 2008 -2012 • Really is symbolic only, since such levels of reduction will likely not significantly impact global warming

D Mean Temperature (°C) 0. 8 Recorded Worldwide Temperatures 0. 6 0. 4 0. 2 0. 0 -0. 2 -0. 4 -0. 6 1880 1900 1920 1940 Year 1960 1980 2000

2007 Temperature Changes Compared to 1951 -1980 -3 -2. 5 -1 -. 5 -. 1 . 5 1 1. 5 2. 5 3. 4

Past Temperatures Measurement • Proxy – a method that approximates a particular measurement (e. g. , temperature) • • • Ice cores Pollen records Plant macrofossils Sr/Ca isotope data Oxygen isotopes from speleothem calcite (stalactites and stalagmites)

Temperature History of the Earth • Little ice age (1400 -1840) – 1°C cooler • Medieval warm period (800 -1300) – 1°C warmer than today • Cool/warm cycles occur over ~1, 500 years • Mostly due to changes in thermohaline circulation system of the ocean

Temperature History of the Earth • For the past 3 Ma, the Earth has been experiencing ~100 ka cycles of glaciation followed by ~10 ka interglacial periods • These climate periods are largely the result of cycles in the earth’s orbit – precession, obliquity, and eccentricity

Orbital Parameters & Earth’s Climate Precession (22 ka) Obliquity (41 ka) Eccentricity (100 ka) Temperature 1000 900 800 700 600 500 400 300 200 100 0 Age (ka)

Temperature History of the Earth • For the past 3 Ma the earth has been experiencing ~100 ka cycles of glaciation followed by ~10 ka interglacial periods • Last ice age began ending 15, 000 years ago, but was interrupted by the “Younger Dryas” event 12, 900 years ago

Temperature Change (°C) “Hockey Stick” Controversey 0. 6 0. 4 Direct temperature measurements Mann et al. 1999 0. 2 0 -0. 2 -0. 4 -0. 6 -0. 8 1000 1200 1400 1600 Year 1800 2000

CO 2 (ppm) Antarctica 370 320 270 220 170 600000 400000 200000 Time (YBP) 31 30 29 28 27 26 025 SST (°C) Tropical Pacific CO 2 Concentration Vs. Temperature

Temperature Change (°C) Consequences of Global Warming: Primarily Impacts the Northern Hemisphere and Land Masses 1. 0 Northern vs. Southern Latitude 0. 8 0. 6 Northern Hemisphere Southern Hemisphere Land vs. Ocean Land Ocean 0. 4 0. 2 0. 0 -0. 2 -0. 4 -0. 6 1920 1960 Year 2000

2007 Temperature Changes Compared to 1951 -1980 -3 -2. 5 -1 -. 5 -. 1 . 5 1 1. 5 2. 5 3. 4

Consqeuences of Global Warming: Ice Sheets Melting? • GRACE (gravity measured by satellite) found melting in Antarctica equivalent to sea level rise of 0. 4 mm/year (2 in/century) • Zwally, 2005 (satellite radar altimetry) • confirmed Antarctica melting • Greenland ice melting on exterior, accumulating inland (higher precipitation) • And - Glaciers are retreating all over the world.

Consqeuences of Global Warming: Rise in Sea Levels? • Present rate is 1. 8 ± 0. 3 mm/yr (7. 4 in/century) • Accelerating at a rate of 0. 013 ± 0. 006 mm/yr 2 • If acceleration continues, could result in 12 in/century sea level rise • Scenarios claiming 1 meter or more rise are probably unrealistic

Consqeuences of Global Warming: How Much Temperature Increase? • Some models propose up to 9°C increase this century • Two studies put the minimum at 1. 5°C and maximum at 4. 5°C or 6. 2°C • Another study puts the minimum at 2. 5°C • Summary – most studies suggest ~4°C over the next century

Potential Worldwide Precipitation Changes -50 -20 -10 -5 5 10 20 50

Mitigation of Global Warming? • Conservation • Reduce energy needs • Recycling • Alternate energy sources • • • Nuclear Wind Geothermal Hydroelectric Solar Fusion?

Conclusions • Global warming is happening • Most warming is probably the result of human activities – but this is still under debate • There will be positive and negative (mostly) repercussions from global warming • The costs to mitigate global warming will be high – are they worthwhile?

• Extra slides 2010 beyond this point

Historic Los Angeles Temperature (°C) 22 Annual Temperatures 25 Summer Temperatures 17 21 24 16 20 23 15 19 22 14 18 21 13 17 20 12 16 19 11 Winter Temperatures 15 18 10 1880 1900 1920 1940 1960 1980 2000 Year

Main Ocean Currents Adapted from IPCC SYR Figure 4 -2

Temperature (°C) -25 -30 0. 35 Younger Dryas 0. 30 Medieval Warm -35 -40 Ice Age 0. 25 Little Ice Age 0. 20 -45 0. 15 -50 0. 10 -55 20 15 10 Age (ka) 5 0. 05 0 Snow Accumulation (m/yr) Younger Dryas Event – Greenland Data

Temperature Change (°C) Is the Hockey Stick Correct? 2 Mann et al. 1999 Esper et al. 2002 1 0 -1 -2 800 1000 1200 1400 Year 1600 1800 2000

Is the Hockey Stick Correct? Temperature Change (°C) 0. 4 0. 2 0. 0 -0. 2 -0. 4 -0. 6 Mann et al. 1999 Esper et al. 2002 Moberg et al. 2005 Mann et al. 2008 -0. 8 -1. 0 -1. 2 0 400 800 1200 Year 1600 2000

Temperature Change (°C) U. S. National Academy of Sciences: June 2006 0. 4 “ 2: 1 chance of being right” “high level of confidence” 0. 2 0 -0. 2 -0. 4 -0. 6 -0. 8 1000 1200 1400 1600 Year 1800 2000

Relative Sea Level (cm) Global Temperature Change 20 Changing Sea Levels 10 0 -10 -20 1700 Amsterdam, Netherlands Brest, France Swinoujscie, Poland 1750 1800 1850 1900 1950 2000 Adapted from IPCC SYR Figure 2 -5

20 31 0 30 -20 29 -40 28 -60 -80 27 -100 26 -120 25 450 400 350 300 250 200 150 100 50 Time (Ka) 0 SST (°C) Tropical Pacific Sea Level (m) Sea Levels for 450, 000 Years