FUNDAMENTALS OF GLOBAL CLIMATE CHANGE : LEARNING FROM GLOBAL

DISASTER LABORATORIES

FUNDAMENTALS OF GLOBAL CLIMATE CHANGE

WHAT DO WE NOT KNOW FOR CERTAIN?

THE ISSUECOULD human activities exacerbate the “unnatural” Greenhouse effect by increasing certain greenhouse gases (e.g., CO2) above normal (i.e., safe) levels; if so, can we do anything to slow or reverse the undesirable trend?

THE ISSUE: HUMAN INFLUENCES

Are humans exacer-bating GLOBAL WARMING by adding too much carbon dioxide to the normal levels of greenhouse gases in the atmosphere through rapidly increasing global use of fossil fuels.

HUMAN INFLUENCES Aerosols, smoke and

sulfates reflect sunlight away from the Earth, which outweigh the temporary, localized cooling effects from aerosols and the smoke and sulfates from industry.

HUMAN INFLUENCES ON LAND SURFACES

Once tropical forests (a carbon sink) are cleared for cattle ranching or community development, the cleared land can becomes a major source of methane, a greenhouse gas.

FUNDAMENTALS OF GLOBAL CLIMATE CHANGE

WHAT DO WE THINK WE KNOW FOR CERTAIN?

GCC: LITHOSPHERE-HYDROSPHERE-ATMOSPHERE-BIOSPHERE INTERACTIONS

WHAT DO WE KNOW?

THE EARTH’S GREENHOUSE EFFECT OCCURS NATURALLY.

PLANET EARTH (THE BLUE PLANET) AND THE SOLAR INPUT

PHYSICAL INTERACTIONS OCCUR ON MANY DIFFERENT SCALES

• Propagation, reflection, and refraction of light and EM waves radiated from the sun (i.e., the solar input to Planet Earth)

WHAT DO WE KNOW?

ABOUT 33 PERCENT OF THE INCOMING SOLAR INPUT IS REFLECTED BACK TO SPACE BY CLOUDS, SNOW, ICE, AND, TO A LESSER DEGREE, BY LAND AND WATER SURFACES.

WHAT DO WE KNOW? THE BALANCE (ABOUT 70

PERCENT) OF THE INCOMING SOLAR INPUT IS ABSORBED BY LAND, AIR, WATER, AND ICE.

WHAT DO WE KNOW? THE SOLAR SPECTRUM

INCLUDES: A) VISIBLE LIGHT (ROYGBIV), ALONG WITH: B) ULTRAVIOLET LIGHT (SHORTER WAVE LENGTHS), AND C) INFRARED LIGHT (LONGER WAVE LENGTHS).

PHYSICAL INTERACTIONS OCCUR ON MANY DIFFERENT SCALES

• Absorption, storage, and re-radiation of light and EM waves causes the “natural” greenhouse effect).

WHAT DO WE KNOW? THE GREENHOUSE EFFECT

OCCURS WHEN AN EARTH WARMED BY THE SOLAR SPECTRUM RADIATES INVISIBLE INFRARED LIGHT BACK, BUT…

WHAT DO WE KNOW?CONTINUED …INSTEAD OF GOING BACK

TO SPACE, IT IS PARTLY ABSORBED BY GREENHOUSE GASES IN THE ATMOSPHERE

NOTE: ABSORPTION MAKES THE ATMOSPHERE WARMER.

GREENHOUSE GASES IN THE ATMOSPHERE

“Greenhouse" gases include water vapor, carbon dioxide, methane and nitrous oxide.

WATER VAPORWater vapor is the

most potent greenhouse gas

Higher air temperatures increase the rate of water vaporization.

VOLCANIC ERUPTIONS

Volcanic eruptions add water vapor and ash to the atmosphere.

PHYSICAL INTERACTIONS OCCUR ON MANY DIFFERENT SCALES

• Absorption of heat by greenhouse gases in the atmosphere causes the “unnatural” greenhouse effect).

“UNNATURAL”GREENHOUSE EFFECT

Greenhouse gases trap heat inside the atmosphere.

Too much trapped heat increases temperatures in the atmosphere and on the land and ocean surfaces, which causes climate change.

WHAT DOES IT ALL MEAN?• THE “NATURAL” GREENHOUSE

EFFECT KEEPS THE EARTH WARM AT ABOUT 57.9 DEGREES F, AND

• THE “UNNATURAL”GREENHOUSE EFFECT CAUSES THE ATMOSPHERE’S TEMPERATURE TO RISE, FOLLOWED BY A RISE IN LAND AND OCEAN TEMPERATURES, CAUSING CLIMATE CHANGE ON A GLOBAL SCALE

WHAT DO WE KNOW? SATELLITE MEASUREMENTS

INDICATE THAT THE TROPO-SPHERE IS WARMING FASTER THAN THE EARTH’S SURFACE.

NOTE: THIS INDICATES THAT GREENHOUSE GASES IN THE ATMOSPHERE ARE ABSORBING TOO MUCH HEAT.

2005 - HOTTEST YEAR ON RECORD

• According to NASA and other organizations, 2005 was the hottest year on record for the Northern Hemisphere.

• Temperatures were about 1.4 degrees Fahrenheit above the historical average.

A WARMING EARTH: SEPT 25, 2007

THE AVERAGE GLOBAL TEMPERATURE HAS RISEN 1.7

DEGREES F IN PAST 150 YEARS

WHAT DO WE KNOW?

AVERAGE GLOBAL SEA LEVEL HAS INCREASED BY 4.7 INCHES SINCE THE LAST ICE AGE.

WHAT DO WE KNOW?

SEA LEVEL RISES FOR TWO REASONS:

WATER EXPANDS WHEN IT IS WARMED, AND

WATER VOLUME INCREASES AS MELT WATER IS ADDED.

WHAT DO WE KNOW?

• IF THE FLOATING ARCTIC ICE CAPS MELT, GLOBAL SEA LEVEL WILL NOT BE AFFECTED.

• IF ALL THE SNOW AND ICE IN GREENLAND MELTED, GLOBAL SEA LEVEL WILL RISE 24 FEET.

CLOUDS CAUSE BOTH COOLING AND WARMING

Clouds cool Earth by reflecting incoming solar energy.

Clouds cool Earth by slowing evaporation.

Clouds warm Earth by trapping heat being re-radiated upward from the Earth’s surface.

LAND SURFACES AFFECT TEMPERATURES AND MOISTURE

Mountain ranges can block clouds, creating "dry" shadows downwind.

Sloping land facilitates water runoff, leaving the land and air drier.

ROLE OF ICE AND SNOWIce and snow

reflects heat outward into space, cooling Planet Earth in the process.

When ice melts, ocean water looses some of its stored heat.

THE OCEANS ARE A NATURAL CARBON SINK

The oceans and marine life remove and/or consume huge amounts of carbon dioxide.

THE OCEANS STORE HEAT BETTER THAN LAND DOES

Oceans, the source of moisture in the air, store heat more effectively over the long term than land and transports it efficiently over distances of thousands of miles.

WHAT DO WE KNOW?

THE ALBEDO (PERCENT OF LIGHT REFLECTED) FOR FRESH SNOW IS 80-90 PERCENT,

BUT IT IS ONLY 50 – 60 PERCENT FOR MELTING ICE.

WHAT DO WE KNOW?

CARBON DIOXIDE ENTERS THE ATMOSPHERE NATURALLY, AND IT LEAVES THE ATMOSPHERE NATURALLY.

WHAT DO WE KNOW?

• AS THE GREENHOUSE EFFECT INCREASES, TEMPERATURES IN THE ATMOSPHERE INCREASES AND THE REMOVAL RATE OF CARBON DIOXIDE DECREASES.

SUMMARY

WHAT DO WE KNOW?• WITHOUT THE “NATURAL”

GREENHOUSE EFFECT, PLANET EARTH WOULD BE MUCH COLDER; E.G., A TEMPERATURE OF ABOUT

MINUS 2 DEGREES F.

WHAT DO WE KNOW?• IF THE “UNNATURAL”

GREENHOUSE EFFECT WERE TO GET OUT OF CONTROL, PLANET EARTH WOULD BE WARMER THAN THE CURRENT AVERAGE TEMPERATURE OF 57.9 DEGREES F.

THE WORLD IS DEBATING THE TIPPING SCENARIO ISSUE

• The “Tipping Scenario Issue” is: “Within a few decades, will humans be virtually helpless to slow the perceived risks associated with global climate change?