Global Warming 011

Winter solstice Dec. 22 Sun vertical at 23.5 o S Winter solstice Dec. 22 Sun vertical at 23.5 o S Autumnal equinox Sep. 23 Sun vertical at equator Summer solstice June 21 Sun vertical at 23.5 o N Vernal equinox March 21 Sun vertical at equator Northern Hemisphere Names

Earth further from sun Earth closer to sun

Solar irradiance- What are some factors that effect exposure to irradiance? The radiant energy emitted by the sun. It is highest at the equator and lowest at the poles. We are interested in conditions near the Earth’s surface

Convection cell model Non-rotating Earth

Add rotation and add landmasses unequal heating and cooling of the Earth

Physical properties of the atmosphere: Density Warm, low density air rises Cool, high density air sinks Creates circular- moving loop of air (convection cell)

Physical properties of the atmosphere: Water vapor Cool air cannot hold much water vapor, so is typically dry Warm air can hold more water vapor, so is typically moist Water vapor decreases the density of air

Physical properties of the atmosphere: Pressure A column of cool, dense air causes high pressure at the surface, which will lead to sinking air A column of warm, less dense air causes low pressure at the surface, which will lead to rising air

ITCZ intertropical convergence zone= doldrums Low pressure, wet climate High pressure, dry climate Low pressure, wet climate 30 o 60 o 90 o 0 o High pressure, dry climate

A)Idealized winds generated by pressure gradient and Coriolis Force. B)Actual wind patterns owing to land mass distribution..

The Coriolis effect –Is a result of Earth’s rotation –Causes moving objects to follow curved paths: In Northern Hemisphere, curvature is to right In Southern Hemisphere, curvature is to left –Changes with latitude: No Coriolis effect at Equator Maximum Coriolis effect at poles

The Coriolis effect on Earth As Earth rotates, different latitudes travel at different speeds The change in speed with latitude causes the Coriolis effect

equator Quito Buffalo 79 o W North Pole South Pole N Quito Buffalo equator Buffalo moves 783 mph Quito moves 1036 mph 15 o

Gyres are large circular-moving loops of water subtropical gyres Five main gyres (one in each ocean basin): North Pacific South Pacific North Atlantic South Atlantic Indian Generally 4 currents in each gyre Centered about 30 o north or south latitude Current Gyres

Geostrophic flow and western intensification Geostrophic flow causes a hill to form in subtropical gyres The center of the gyre is shifted to the west because of Earth’s rotation Western boundary currents are intensified Figure 7-7

Wind-driven surface currents

Global Warming

The E-M Spectrum

Fate of Solar Radiation Reaching the Earth reflectionclouds snow and ice the earth’s surface atmospheric dust reflectionclouds snow and ice the earth’s surface atmospheric dust

Fate of Solar Radiation Reaching the Earth absorptionatmosphereoceansland plant photosynthesis absorptionatmosphereoceansland

Fate of Solar Radiation Reaching the Earth radiationradiation

The Greenhouse Effect

Greenhouse Gases Carbon Dioxide Methane Nitrous Oxide Water Vapor Ozone

Thousands of Years Before Present Temperature Change ( o F) Atmospheric CO 2 (ppm)

Year Temperature Carbon Dioxide Temperature Change ( o F) Atmospheric CO 2 (ppm) Atmospheric CO 2 & Surface Temperature Trends

b Sea level rise b Increased plant primary productivity b Shifts in the distribution of plants and animals b Water contamination and outbreaks of water-borne diseases b Increased storm severity b Potential melting or enlargement of polar ice caps b Changes to patterns of rainfall b More severe droughts or increased precipitation b changes to ocean circulation patterns Predicted changes with increased greenhouse warming

Ice Age 18,000 years ago

Sea Level Changes due to Ice Ages and Ice Cap Melting

Year Changes in Mean Sea Level Mean Sea Level Rise

Summer Arctic Sea Ice Decline Comparison between 1979 & 2005 Summer Arctic Sea Ice Decline Comparison between 1979 & 2005

Early Fall Arctic Sea Ice Extent Sea Ice Extent (million km 2 ) Year

Greenland Seasonal Surface Melting Surface melting

Permafrost

Permafrost melting

Drunken forest

Year North Atlantic Tropical Storms 10-year running average North Atlantic Tropical Storms 10-year running average Named Tropical Storms

1 Meter Sea Level Rise Waikiki

Sea Level Rise Destroys coastal habitat (e.g. salt marshes, mangroves) Destroys human property Increases pollution Decreases freshwater supply

Effect on Marine Life Phytoplankton bloom due to light and temperature cues Changes will impact food web Hypoxia may result

Effect on Fisheries Migrations are in response to temperature May impact fisheries

Effect on Corals Coral bleaching Leads to loss of habitat and food for reef- dependent species

Currents Oceanic conveyor belt may change ocean currents Currents carry plankton Bring food and oxygen Distribute eggs and larvae Remove wastes and pollutants

Salinity Animals have a narrow range of tolerance Glacial melting inputs lots of freshwater

Acidity CO 2 makes water acidic Corals and other calcium carbonate species can’t make skeleton Impact on plankton development impacts food web

Temperature Higher temperature results in less O 2 - Results in hypoxia Ice melting leaves no resting/hunting areas for polar bears Antarctic Krill impacts food web

Invasive Species Algae smothers coral Invasive species out-compete natives

Weather Events More severe weather patterns El Niño Hurricanes Mudslides Forest Fires Drought

Sea Surface Temperature July 24,

Origin and paths of tropical cyclones Tropical cyclones are intense low pressure storms created by: –Warm water –Moist air –Coriolis effect

El Niño-Southern Oscillation (ENSO) El Niño = warm surface current in equatorial eastern Pacific that occurs periodically around Christmastime Southern Oscillation = change in atmospheric pressure over Pacific Ocean accompanying El Niño ENSO describes a combined oceanic- atmospheric disturbance

El Niño Oceanic and atmospheric phenomenon in the Pacific Ocean Occurs during December 2 to 7 year cycle Sea Surface Temperature Atmospheric Winds Upwelling

Normal conditions in the Pacific Ocean

El Niño conditions (ENSO warm phase)

La Niña conditions (ENSO cool phase; opposite of El Niño)

El Ni ñ oNon El Ni ñ o 1997

Non El Niño El Niño thermocline upwelling

El Niño events over the last 62 years Red - Strong El Nino Blue- Strong La Nina Black – moderate (either)

El NiñoLa Niña WeakModStrongWeakModStrong 2011

Effects of severe El Niños

1.What is a convection cell? 2.What are current atmospheric CO 2 levels? 3.What is the fate of the majority of solar radiation that strikes the Earth? 4.What is a drunken forest? 5.What is permafrost? 6.Is global warming a natural event? Inquiry