FUNDAMENTALS OF GLOBAL CLIMATE CHANGE Physical Causes Consequences Prevention, Mitigation, Monitoring, and Adaptation
FUNDAMENTALS OF GLOBAL CLIMATE CHANGE Physical Causes
GLOBAL CLIMATE CHANGE: LITHOSPHERE-HYDROSPHERE-ATMOSPHERE-BIOSPHERE INTERACTIONS
PHYSICALINTERACTIONS OCCUR ON MANY SCALES • Propagation, reflection, and refraction of light and EM waves from the sun (creating the solar input) • Absorption, storage, and re-radiation of light and EM waves (causing the “natural” greenhouse effect). • Absorption of heat by greenhouse gases in the atmosphere (causing the “Unnatural” greenhouse effect).
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? THE GREENHOUSE EFFECT OCCURS WHENAN 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.
THE AVERAGE GLOBAL TEMPERATURE HAS RISEN 1.7 DEGREES F IN PAST 150 YEARS
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.
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.
SOLAR INPUT • After hitting Earth's upper atmosphere, about one - third of the sun's energy is reflected back into space. • The two-thirds that gets through the atmosphere drives Earth's weather engine
WHAT DO WE KNOW? THE SUN PROVIDES AN AVERAGE OF ABOUT 1370 WATTS OF POWER THROUGH EM RADIATION TO EVERY SQUARE METER OF SURFACE IT STRIKES. NOTE: THIS IS CALLED THE SOLAR CONSTANT.
WHAT DO WE KNOW? THE SOLAR SPECTRUM INCLUDES: VISIBLE LIGHT (ROYGBI), ULTRAVIOLET LIGHT (A WAVE LENGTH TOO SHORT TO SEE),AND INFRARED LIGHT(A WAVE LENGTH TOO LONG TO SEE).
WHAT DO WE KNOW? ABOUT 33 PERCENT OF THE INCOMINGSOLAR SPECTRUM IS REFLECTED BACK TO SPACE FROM CLOUDS, SNOW, AND, TO A LESSER DEGREE, BY LAND SURFACES..
WHAT DO WE KNOW? THE BALANCE (ABOUT 70 PERCENT) OF THE INCOMING SOLAR SPECTRUM IS ABSORBED BY LAND, AIR, WATER, OR ICE.
THE OCEANS STORE HEAT • 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 EARTH’S OCEANS ABSORB 20 TIMES AS MUCH HEAT AS THE EARTH’S ATMOSPHERE. THE pH LEVELOF THE EARTH’S OCEANS HAS INCREASED. NOTE: THE pH INCREASES AS CARBON DIOXIDE IS ABSORBED.
WHAT DO WE KNOW? SEA LEVEL RISES FOR TWO REASONS: WATER EXPANDSWHEN IT IS WARMED, AND WATER VOLUME INCREASES AS MELT WATER IS ADDED.
WHAT DO WE KNOW? AVERAGE GLOBAL SEA LEVEL HAS INCREASED BY 4.7 INCHESSINCE THE LAST ICE AGE.
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.
ICE AND SNOW • Ice and snow reflects heat outward into space, cooling Planet Earth in the process. • When ice melts into the ocean, the ocean water losses some of its stored heat.
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.
GREENHOUSE GASES IN THE ATMOSPHERE • “Greenhouse" gases include water vapor, carbon dioxide, methane and nitrous oxide.
WATER VAPOR • Higher air temperatures increase the rate of water vaporization. • Water vapor is the most potent greenhouse gas.
VOLCANIC ERUPTIONS • Volcanic eruptions add water vapor and ash to the atmosphere.
“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 DO WE KNOW? THE GREENHOUSE EFFECT OCCURS NATURALLY. HUMAN ACTIVITIES EXACERBATE THE “UNNATURAL” GREENHOUSE EFFECTBY INCREASING CERTAIN GREENHOUSE GASES (E.G., CO2) ABOVE HISTORIC LEVELS.
WHAT DO WE KNOW? WITHOUT THE “NATURAL” GREENHOUSE EFFECT, PLANET EARTH WOULD BE MUCH COLDER; E.G., A TEMPER-ATURE OF ABOUT MINUS 2 DEGREES F.
WHAT DO WE KNOW? WITH AN “UNNATURAL” GREENHOUSE EFFECT,PLANET EARTH WOULD BE WARMER THAN THE CURRENT AVERAGE TEMPERATURE OF 57.9 DEGREES F.
WHAT DO WE KNOW? CARBON DIOXIDE ENTERS THE ATMOSPHERE NATURALLY, AND NATURE REMOVES CARBON DIOXIDE FROM THE ATMOSPHERE NATURALLY.
THE OCEANS ARE A NATURAL CARBON SINK • The oceans and marine life remove and/or consume huge amounts of carbon dioxide.
WHAT DO WE KNOW? AS THE GREENHOUSE EFFECT INCREASES TEMPERATURES IN THE ATMOSPHERE,THE REMOVAL RATE OF CARBON DIOXIDE IS DECREASED.
HUMAN INFLUENCES • Humans are exacerbating warming by adding much more carbon dioxide to the greenhouse gases that are naturally present in the atmosphere, through …. • Extensive 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 Consequences
THE WATER CYCLE AND THE “UNNATURAL” GREENHOUSE EFFECT • Higher air temperatures increase the rate of water vaporization (Water vapor is the most potent greenhouse gas) and accelerate the melting of ice. .
THE CONSEQUENCES OF GLOBAL CLIMATE CHANGE • Worldwide rise in sea level. • Collapse of the Atlantic thermohaline circulation (“The Atlantic Conveyor Belt”). • Increased probability of severe windstorms. • Larger storm surges in seasonal hurricanes and typhoons. • Prolonged droughts in some regions and heavy precipitation in others.
THE CONSEQUENCES OF GLOBAL CLIMATE CHANGE • Reduced fresh water for a large portion of humankind that presently obtains its fresh water from glacier-fed rivers. • Loss of function of activities such as winter ski resorts.
ATLANTIC THERMOHALINE CIRCULATION • The Atlantic Conveyor Belt keeps Europe from becoming a deep freeze in the winter. • Ancient sediments, ice cores, and fossils indicate that the Atlantic Conveyor Belt shifted abruptly about 8,200 years ago, when a sudden cooling occurred.
ATLANTIC CONVEYOR BELT • As a result, the land temperature in Greenland dropped more than 9 degrees Fahrenheit within ONE OR TWO decades, an effect that could prove disastrous for Europe.
GREENLAND • Greenland's glaciersare melting into the sea twice as fast as the previously calculated rate offour miles per year. • This faster rate, if continued in concert with similar observations in the Himalayas and South America, makes predictionsof how quickly Earth's oceans will rise over the next centuryquestionable and probably obsolete.
GREENLAND AND ANTARCTICA • The ice sheets in Greenland and Antarcticaare among the largest reservoirs of fresh water on Earth. • How muchsea levelwillrise as a result of faster melting is unclear. • Current estimates of around 50 cm (20 in) over the next centurymay be much too low.