google groups help other available help

Google Groups Google Groups HelpHelp http://groups.http://groups.googlegoogle.com/group/met-10.com/group/met-10

Other available helpOther available help Office hours 8:15 – 9:00 a.m. Office hours 8:15 – 9:00 a.m.

Monday/WednesdayMonday/Wednesday Email at Email at shaunshaun@@wundergroundwunderground.com.com Call me at (415) 205-2083Call me at (415) 205-2083 Meteorology department help on 6Meteorology department help on 6thth floor floor

http://groups.google.com/group/met-10



mailto:[email protected]




Chapter 14: Chapter 14: Climate ChangeClimate Change

The earth’s changing climateThe earth’s changing climate Possible causes of climatic changePossible causes of climatic change Global warmingGlobal warming

Why Climate Change Why Climate Change MattersMatters

Why should you be aware of climate Why should you be aware of climate change?change?

Climate is changing and your Climate is changing and your generation will be the one to make generation will be the one to make or break itor break it Climate change (whether nature or Climate change (whether nature or manmade) will directly affect you!manmade) will directly affect you!

Determining Past Determining Past ClimatesClimates

How do we know what past climates How do we know what past climates were like?were like?

Fossil evidenceFossil evidence Fossils of tundra plants in New England Fossils of tundra plants in New England

suggest a colder climatesuggest a colder climate Ocean sediment coresOcean sediment cores

Certain animals must have lived in a Certain animals must have lived in a range of ocean temperaturesrange of ocean temperatures

Oxygen isotope ratiosOxygen isotope ratios Differing isotope counts mean differing Differing isotope counts mean differing

temperaturestemperatures

Determining Past Determining Past ClimatesClimates

How do we know what past climates How do we know what past climates were like?were like?

Ice coresIce cores Sulfuric acid in ice coresSulfuric acid in ice cores Oxygen isotopes (cold the air, the more Oxygen isotopes (cold the air, the more

isotopes)isotopes) Bubbles in the ice contain trapped Bubbles in the ice contain trapped

composition of the past atmospherescomposition of the past atmospheres DendrochronologyDendrochronology

Examining tree rings to see growth Examining tree rings to see growth patternspatterns

Climate Through the Climate Through the AgesAges

Much of Earth’s history was warmer than Much of Earth’s history was warmer than today by as much as 15°Ctoday by as much as 15°C

Ice ageIce age Most recently 2.5 m.y.a.Most recently 2.5 m.y.a. Beginning marked by glaciers in North AmericaBeginning marked by glaciers in North America Interglacial periods (between glacial advances)Interglacial periods (between glacial advances) When glaciers were at their max (18,000 – 22,000 When glaciers were at their max (18,000 – 22,000

years ago) sea level 395 feet lower than todayyears ago) sea level 395 feet lower than today This is when the sea bridge was exposedThis is when the sea bridge was exposed

• 20,000 years ago the sea level was so low that the20,000 years ago the sea level was so low that theEnglish Channel didn’t even exist.English Channel didn’t even exist.


Temps began to rise 14,000 years Temps began to rise 14,000 years agoago

Then temps sank again 12,700 years Then temps sank again 12,700 years agoago This is known as the This is known as the Younger-DryasYounger-Dryas


Temps rose again to about 5,000 Temps rose again to about 5,000 years ago (years ago (Holocene MaximumHolocene Maximum). ). Good for plantsGood for plants

Climate During the Past Climate During the Past 1000 Years1000 Years

At 1000, At 1000, Europe was Europe was relatively relatively warm. warm. Vineyards Vineyards flourished and flourished and Vikings Vikings settled settled Iceland and Iceland and GreenlandGreenland


From 1000-From 1000-13001300

Huge famines Huge famines due to large due to large variations in variations in weather. weather. Crops Crops suffered.suffered.

Floods and Floods and great droughtsgreat droughts


From 1400-From 1400-18001800

Slight cooling Slight cooling causes glaciers causes glaciers to expandto expand

Long winters, Long winters, short short summers. summers. Vikings diedVikings died

Known as the Known as the Little Ice AgeLittle Ice Age


Little Ice AgeLittle Ice Age 1816 – “1816 – “Year Year

Without A Without A summersummer””

Very cold Very cold summer summer followed by followed by extremely cold extremely cold winterwinter

Temperature Trend Temperature Trend During the Past 100-plus During the Past 100-plus

YearsYears Warming from 1900 to 1945Warming from 1900 to 1945 Cooling to 1960, then increasing to Cooling to 1960, then increasing to

todaytoday

Temperature Trend Temperature Trend During the Past 100-plus During the Past 100-plus

YearsYears Sources of temperature readingsSources of temperature readings

Over land, over ocean, sea surface Over land, over ocean, sea surface tempstemps

Warming in 20Warming in 20thth century is 0.6°C century is 0.6°C Is global warming natural or manmade?Is global warming natural or manmade?

External Causes of External Causes of Climate ChangeClimate Change

How can we change the climate?How can we change the climate?

• Emissions of COEmissions of CO22 and other greenhouse gases are and other greenhouse gases are

by no means the only way to change the climate.by no means the only way to change the climate.

Changes in incoming solar radiationChanges in incoming solar radiation Changes in the composition of the Changes in the composition of the

atmosphereatmosphere Changes in the earth’s surfaceChanges in the earth’s surface

Climate Change and Climate Change and Feedback MechanismsFeedback Mechanisms

Water vapor-greenhouse feedbackWater vapor-greenhouse feedback Explain it (is it positive or negative?)Explain it (is it positive or negative?) Runaway greenhouse effectRunaway greenhouse effect

Negative feedback mechanismsNegative feedback mechanisms Increase in temp…increase in radiant Increase in temp…increase in radiant

energy to spaceenergy to space What planet as a runaway greenhouse What planet as a runaway greenhouse

effect?effect? Snow-albedo feedbackSnow-albedo feedback (what kind is it?) (what kind is it?)

Climate Change, Plate Climate Change, Plate Tectonics, and Mountain-Tectonics, and Mountain-

buildingbuilding Theory of plate tectonics – moving of plates like Theory of plate tectonics – moving of plates like

boats on a lakeboats on a lake Evidence of plate tectonicsEvidence of plate tectonics

Glacial features in Africa near sea levelGlacial features in Africa near sea level Fossils of tropical plants in high latitudesFossils of tropical plants in high latitudes

Climate Change, Plate Climate Change, Plate Tectonics, and Mountain-Tectonics, and Mountain-

buildingbuilding Landmasses at high latitude create Landmasses at high latitude create

glaciersglaciers Arrangements of landmasses disturb Arrangements of landmasses disturb

ocean currentsocean currents Mountain building by plates running into Mountain building by plates running into

each othereach other

Climate Change and Climate Change and Variations in the Earth’s Variations in the Earth’s

OrbitOrbit Milankovitch theoryMilankovitch theory

As Earth moves around the sun, three As Earth moves around the sun, three different movements affect solar different movements affect solar radiationradiation


OrbitOrbit EccentricityEccentricity Change in the shape of the orbit (from circular Change in the shape of the orbit (from circular

to ellipticalto elliptical Cycle is 100,000 yearsCycle is 100,000 years More elliptical,More elliptical,

more variation in more variation in

solar radiationsolar radiation

Presently inPresently in

Low eccentricityLow eccentricity


OrbitOrbit ObliquityObliquity

Change in the tilt of Earth’s axisChange in the tilt of Earth’s axis Cycle is 41,000 yearsCycle is 41,000 years Smaller the tilt, the less seasonalSmaller the tilt, the less seasonal

variationvariation Axis tilts from 22° to 24.5°Axis tilts from 22° to 24.5° What is our current tiltWhat is our current tilt


OrbitOrbit ProcessionProcession

Wobble of the Earth as it spinsWobble of the Earth as it spins The Earth wobbles like a topThe Earth wobbles like a top Currently, closest to the sun inCurrently, closest to the sun in

JanuaryJanuary In 11,000 years, closest to theIn 11,000 years, closest to the

sun in Julysun in July


OrbitOrbit

Climate Change and Climate Change and Atmospheric ParticlesAtmospheric Particles

Sulfate aerosolsSulfate aerosols Put into the atmosphere by sulfur fossil Put into the atmosphere by sulfur fossil

fuels and volcanoesfuels and volcanoes

• Sulfate aerosols are thought to Sulfate aerosols are thought to cool the climatecool the climate and andtherefore counteract global warming to some extent.therefore counteract global warming to some extent.


Volcano aerosolsVolcano aerosols May get into the stratosphere and May get into the stratosphere and

absorb and reflect sunlightabsorb and reflect sunlight Thus, warms the stratosphere and cools Thus, warms the stratosphere and cools

the tropospherethe troposphere


Volcanic eruptions Volcanic eruptions may be may be responsibleresponsible for many of the climate’s for many of the climate’s cooling periods (Little Ice Age)cooling periods (Little Ice Age)

Eruptions were larger 2.5 m.y.a and Eruptions were larger 2.5 m.y.a and may be responsible for the Ice Agemay be responsible for the Ice Age

Climate Change and Climate Change and Variations in Solar Variations in Solar

OutputOutput SunspotsSunspots – magnetic storms on the – magnetic storms on the

sun that show up as dark regionsun that show up as dark region Maximum Maximum

sunspots, sunspots, maximum maximum emission (11 emission (11 years)years)

Maunder Maunder minimumminimum – – 1645 to 1715 1645 to 1715 when few when few sunspots sunspots happenedhappened

The Recent WarmingThe Recent Warming

Radiative forcing agentsRadiative forcing agents – – greenhouse gases that can disturb greenhouse gases that can disturb the radiative equilibriumthe radiative equilibrium

• Climate models are used to see Climate models are used to see the futurethe future

• They use data from Carbon They use data from Carbon dioxide, other greenhouse gases, dioxide, other greenhouse gases, aerosols, and moreaerosols, and more

Future Warming - Future Warming - Projections, Questions Projections, Questions

and Uncertaintiesand Uncertainties Questions and uncertaintiesQuestions and uncertainties

How fast will Carbon dioxide increase?How fast will Carbon dioxide increase? Can we stop deforestation?Can we stop deforestation? Can we stop burning fossil fuels?Can we stop burning fossil fuels?

Future Warming - Future Warming - Projections, Questions Projections, Questions

and Uncertaintiesand Uncertainties Uncertain effect of cloudsUncertain effect of clouds

More clouds, more reflection to space?More clouds, more reflection to space? More clouds, more longwave radiation More clouds, more longwave radiation

absorbed?absorbed?

Possible Consequences Possible Consequences of Global Warmingof Global Warming

Projected temperaturesProjected temperatures Temperatures will rise most in high latitudesTemperatures will rise most in high latitudes Expanding boreal forest will increase tempsExpanding boreal forest will increase temps Plants and animals will diePlants and animals will die Precipitation will increase worldwidePrecipitation will increase worldwide

Possible effects on global circulationPossible effects on global circulation Weather shifts from normal patternWeather shifts from normal pattern More rain than snow in the WestMore rain than snow in the West Rise in sea levelRise in sea level Melting glaciersMelting glaciers Contamination of groundwaterContamination of groundwater

Possible Consequences Possible Consequences of Global Warmingof Global Warming

Fig. 14-20, p. 407

Global Warming and Global Warming and Human Impact on the Human Impact on the

Earth’s SurfaceEarth’s Surface DesertificationDesertification – process of – process of

overgrazing and excessive overgrazing and excessive cultivation of grasslands, causing cultivation of grasslands, causing desert conditionsdesert conditions

An interesting theoryAn interesting theory Plagues could be nature’s way of Plagues could be nature’s way of

“curing” the Earth of Global Warming“curing” the Earth of Global Warming Plagues kills us and our effects, allowing Plagues kills us and our effects, allowing

the Earth to heal (Gaia Hypothesis)the Earth to heal (Gaia Hypothesis)

Curbing Global WarmingCurbing Global Warming

Kyoto ProtocolKyoto Protocol A format agreement by hundreds of nations A format agreement by hundreds of nations

to curb greenhouse emissionsto curb greenhouse emissions Try to reduce emissions by 5% below 1990 Try to reduce emissions by 5% below 1990

levels by 2012levels by 2012 GeoengineeringGeoengineering

Trying to fix the atmosphere with Trying to fix the atmosphere with technologytechnology

Idea to put sulfate aerosols into Idea to put sulfate aerosols into atmosphere to cool itatmosphere to cool it

google groups help other available help

Documents