Earth's Atmosphere 78% Nitrogen 21% Oxygen gas is ionized by solar radiation ozone is O 3, which absorbs solar UV efficiently, thus heating stratosphere commercial jet altitudes temperature on a cool day Original gases disappeared. Atmosphere is mostly due to volcanoes and plants!

Ozone Hole over Antarctica Led to banning of Chlorofluorocarbons worldwide Had been used in refrigerators/air conditioners, aerosol cans, and as a cleaning solvent

Rescue Balls and What landed in Roswell

Clicker 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.

CO 2 in Atmosphere and Temperature

CO 2 in Atmosphere

Temperature Predictions.

Alaska is Ground Zero Chapman and Walsh, 2004 In past 50 years, Alaska: Temperatures have increased 4 o F overall (National Assessment Synthesis Team) Worldwide: Temperatures have increased Slightly more than 1 o F (IPCC 2007) Surface Air Temperature Trends Global Warming Basics Global Warming: The Greatest Threat © 2006 Deborah L. Williams Chapman and Walsh, 2004

 Snow and sea ice reflect 85-90% of sun’s energy.  Ocean surface and dark soil reflect only 10-20%. The Albedo Effect “White shirt versus Black shirt” Why has Alaska warmed the most? Increased melting of snow and sea ice Increased melting of snow and sea ice More of sun’s heat energy is absorbed More dark earth and ocean surface is exposed More dark earth and ocean surface is exposed Land or water warms faster Global Warming Basics Global Warming: The Greatest Threat © 2006 Deborah L. Williams (ACIA 2004)

Source ACIA, 2004 Jennifer Allen Animation  An area twice the size of Texas has melted away since 1979 (over 20% decrease). (National Snow and Ice Data Center 2005)  Ice 40% thinner. (Rothrock,D.A, et al. 1999)  Ice only 6 – 9 feet thick at North Pole ( NOAA FAQ 2007).  Northwest passage opened Aug 21, 2007 Impacts in Alaska 1. Melting Melting Sea Ice | | | | | Arctic Sea Ice Extent (millions of sq. km.) Source: NSIDC, 2005 ARCTIC SEA ICE AREA Global Warming: The Greatest Threat © 2006 Deborah L. Williams

Impacts in Alaska 1. Melting  The rapid retreat of Alaska’s glaciers represents about 50% of the estimated mass loss by glaciers through 2004 worldwide. (ACIA 2004)  Loss of over 588 billion cubic yards between ’61 and ’98. (Climate Change 11/05)  Alaska’s glaciers are responsible for at least 9% of the global sea level rise in the past century. (ACIA 2004) Glacier Bay (Riggs Glacier) USGS photo Bruce Molnia photo Glacial Retreat 2003 Matt Nolan photo Austin Post photo 1958 McCall Glacier

Polar bears Walruses Ice seals Black guillemots Kittiwakes Salmon Caribou Arctic grayling Impacts in Alaska 3. Animals Animals at Risk  Rising temperatures  Shrinking habitat  Food harder to get  Expanding diseases  Competition Polar bears Walruses Ice seals Caribou Black guillemots Kittiwakes Salmon Arctic grayling

Ocean Acidification CO 2 + H 2 0 HCO H + Water becomes more acidic. (ACID) Remains in the atmosphere (greenhouse gas) Dissolves in sea water CO 2 Over the last 200 years, about 50% of all CO 2 produced on earth has been absorbed by the ocean. Global Warming: The Greatest Threat © 2006 Deborah L. Williams (Royal Society 6/05)

Inundation  Sea level has increased 3.2 mm/year between 1993 and 2008 (IPCC 2007).  This is times faster than during the last 3,000 years (ACIA 2004).  meters of sea level rise by 2100 if 3 times pre- industrial CO2 or 1% increase/year (Overpeck et al. 2006). As Greenland and Antarctic ice sheets melt...

Ocean Nations Threatened Maldives nation held cabinet meeting 20 feet under water. Tuvalu nation considering exodus (highest elevation is 15 feet) New Moore Island goes under in March 2010

Inundation Inundation from Four Meter Sea Level Rise (or, 1m rise + 3m storm surge) Weiss and Overpeck, 2006

Photo courtesy of 7summits.com What We Can Do 1. Is it Achievable? 2. Action Is Essential at Every Level Individual Corporate Local State Federal International 3. Critical Steps R E D U C E C O 2 E M I S S I O N S Global Warming: The Greatest Threat © 2006 Deborah L. Williams

Carbon Emissions (Billions of tons per year) Current Path At least TRIPLING CO 2 Avoid doubling CO 2 Flat Path STABILIZATION TRIANGLE What We Can Do Is it Achievable? Pacala and Socolow, Science 2004 Global Warming: The Greatest Threat © 2006 Deborah L. Williams

Clicker 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.

Why is it controversial?

Two Kinds of “ Classical ” Planets "Terrestrial" Mercury, Venus, Earth, Mars "Jovian" Jupiter, Saturn, Uranus, Neptune Close to the Sun Small Far from the Sun Large Few Moons No Rings Main Elements Fe, Si, C, O, N: we learn that from the spectra Mostly Rocky High Density ( g/cm 3 ) reminder: liquid water is 1 g/cm 3 Slow Rotation ( days) Mostly Gaseous Low Density ( g/cm 3 ) Many Moons Rings Main Elements H, He Fast Rotation ( days)

Mercury = 5.4 g/cm 3 = 0.38 that of Earth Mass Radius Density Gravity = 3.3 x g = M Earth  = 2439 km = 0.38 R Earth Semimajor axis = 0.39 AU

Discovery of Water Ice on Mercury Goldstone 70m radar received by the VLA Polar regions could be 125 K and never warmed by the Sun

Orbit of Mercury 3:2 resonance with the sun Orbital period of 88 days Sidereal rotation of 59 days 1 “ day ” on mercury = 176 earth days Daytime temp = 500 K Nighttime temp = 100 K

Structure of Mercury And no atmosphere, so no wind or erosion. Surface reflects geologic history well. (from Mariner 10 and theoretical arguments) 1.Crust km thick 2. Mantle 600 km thick 3. Core, 1800 km in radius

Messenger at Mercury in 2011 MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER)

Clicker Question: We think Mercury could have ice at the poles because: A: Mercury is so far from the Sun. B: Optical images show white polar caps. C: Radar images show high reflectivity at the poles. D: Mercury is in a 3:2 spin:resonance orbit around the Sun.

Venus Mass = 0.82 M Earth Radius = 0.95 R Earth  Density = 5.2 g/cm 3 Average distance from Sun = 0.72 AU Orbital period = 225 days Rotation period = 243 days (longer than orbital period, and retrograde!)

Venus' Atmosphere - Pressure at surface is 90 x that of Earth's => much more gas in atmosphere. No oceans. - Consequence - meteoroids burn up easily. No impact craters less than ~3 km. What ’ s the composition of the atmosphere? - Hot at surface K! Almost hot enough to melt rock - Why so hot? Huge amount of CO 2 leads to strong greenhouse effect % CO 2 - Yellowish color from sulfuric acid clouds and haze.

Early on, T may have been much lower (but still warmer than Earth). Oceans existed? But if warm enough, T would start to rise because of... Runaway Greenhouse Effect 1) Water and CO 2 evaporate from oceans into atmosphere. 2) Greenhouse effect more efficient. 3) Temperature rises. 4) More evaporation (back to #1). => complete evaporation of oceans. Thick atmosphere.

The Habitable Zone or “The Goldilocks Problem” In the zone …

Missions to Venus Soviet Venera ( ) Mariner 2, 5 and 10 (1962, 1967 and 1974) Pioneer Venus (1978) Magellan (1989) Venera 13 photo of surface. Rocks are basalt and granite. Color is due to atmosphere. Color corrected for atmosphere.

"Radar Echo" technique measures altitude space probe time for signal to return tells you the altitude of surface feature. Planet Surface

Radar data (Pioneer Venus mission) reveal altitude variations on surface. Flatter than Earth, no evidence for plate boundaries => no large scale plate tectonics. 1 km But plenty of evidence of stresses and fractures on smaller scales => much small-scale shifting of crust

Unlike Moon, larger impact craters distributed randomly over surface => all parts of surface have about same age. Paucity of large impact craters => surface is young, million years? Impact Craters

Volcanism Shield volcano elevation map from Magellan radar data. About 100 km across. Volcanism may be ongoing, based on sulfur dioxide variations in atmosphere. But very little resurfacing in past million years. Venus surface flyover

Volcanism Venus surface flight simulation using data from Magellan.

Clicker Question: Why is Venus the hottest planet in the Solar System? A: It is the closest planet to the Sun. B: There is a lot of radioactive material in the crust. C: There is a large concentration of carbon dioxide in the atmosphere. D: The Russians left the lights on in the Venera 5 landing vehicle. E. Paris Hilton lives there.

Touring Venus

Touring Mars