Human Influence on Human Influence on Weather/ClimateWeather/Climate

Chapter 18 material Chapter 18 material

Well-Accepted Ideas (IPCC)Well-Accepted Ideas (IPCC)

– Human activites causing a rapid rise Human activites causing a rapid rise in atmospheric COin atmospheric CO22

Fossil fuel burningFossil fuel burning Destruction of forestsDestruction of forests

– Human activities have destroyed a Human activities have destroyed a significant significant amount of stratospheric ozoneamount of stratospheric ozone

– Higher global temperatures have Higher global temperatures have correlated with increasing CO correlated with increasing CO22

Land Use ChangesLand Use Changes

Dust BowlDust Bowl– Prairie grass was plowed under and Prairie grass was plowed under and

overgrazedovergrazed– With no grass to hold the soil in place, a With no grass to hold the soil in place, a

naturally occurring prolonged dry spell naturally occurring prolonged dry spell (drought) caused the bare soil to be carried (drought) caused the bare soil to be carried away by the windaway by the wind

Owens LakeOwens Lake

Urban Heat Island effectUrban Heat Island effect

– Cities are warmer, on average, than their Cities are warmer, on average, than their suburbssuburbs Urban Heat IslandUrban Heat Island Increased emission of heat (cars, people)Increased emission of heat (cars, people) Changes in water cyclingChanges in water cycling Changes in surface area and Changes in surface area and

heat capacity heat capacity

The Urban Heat Island: The The Urban Heat Island: The Ultimate Land Use ChangeUltimate Land Use Change

Localized climate Localized climate changechange– Increased runoff = Increased runoff =

warmer daytimes warmer daytimes (less cooling due to (less cooling due to evaporation)evaporation)

– Increased surface Increased surface area = more solar area = more solar radiation can be radiation can be absorbed, more IR absorbed, more IR emitted and re-emitted and re-absorbed at nightabsorbed at night

– Autos, factories, Autos, factories, people = heatpeople = heat

Stratospheric Ozone Stratospheric Ozone DepletionDepletion

– Ozone is good or bad, depending upon where it isOzone is good or bad, depending upon where it is Good: In the Good: In the stratospherestratosphere, where it protects us from , where it protects us from

much of the sun’s harmful ultraviolet radiation, which much of the sun’s harmful ultraviolet radiation, which causes skin cancercauses skin cancer

Bad: In the troposphere, where we are - it is toxic to Bad: In the troposphere, where we are - it is toxic to plants, animals and usplants, animals and us

‘‘Ozone Hole’Ozone Hole’

– CFCs (chlorofluorocarbons) CFCs (chlorofluorocarbons) destroy ozone very destroy ozone very efficiently, used in many efficiently, used in many things in 20things in 20thth century century

– Ozone “hole” is an area over Ozone “hole” is an area over the south pole where the south pole where stratospheric stratospheric ozone levels have drastically ozone levels have drastically fallenfallen

– Atmospheric conditions Atmospheric conditions (extreme cold, (extreme cold, polar vortex) lead to efficient polar vortex) lead to efficient ozone destruction thereozone destruction there

An international environmental An international environmental positivepositive

Have been banned and atmospheric Have been banned and atmospheric CFC levels are leveling off (1987)CFC levels are leveling off (1987)

As atmospheric CFC levels decline, As atmospheric CFC levels decline, stratospheric ozone should recover, but stratospheric ozone should recover, but there is a significant delay between there is a significant delay between CFC reduction and ozone recoveryCFC reduction and ozone recovery

Global Warming: The Global Warming: The EnhancedEnhanced Greenhouse Effect Greenhouse Effect

Greenhouse EffectGreenhouse Effect keeps our planet about keeps our planet about 60F warmer than it otherwise would be. Life 60F warmer than it otherwise would be. Life as we know it depends upon this effect. as we know it depends upon this effect. Greenhouse gases (primarily water vapor and Greenhouse gases (primarily water vapor and carbon dioxide) absorb/re-emit IR radiation.carbon dioxide) absorb/re-emit IR radiation.

Enhanced Greenhouse EffectEnhanced Greenhouse Effect

““Global Warming”Global Warming”– Too much of a “good” thingToo much of a “good” thing– Anthropogenic (human-induced)Anthropogenic (human-induced)

COCO22

MethaneMethane CFCs – low concentrations, but very efficient IR CFCs – low concentrations, but very efficient IR

absorbers (replacements of CFCs also very efficient absorbers (replacements of CFCs also very efficient IR absorbers)IR absorbers)

So the earth is warming on average…what So the earth is warming on average…what does that mean?does that mean?

GlobalGlobal Warming: UncertaintiesWarming: Uncertainties

JUST A FEW OF THE POTENTIAL EFFECTSJUST A FEW OF THE POTENTIAL EFFECTS Cloud cover: Should increase as condensation nuclei Cloud cover: Should increase as condensation nuclei

(pollution) increase, but (pollution) increase, but typetype of cloud has an effect on of cloud has an effect on surface temperature. Some cause cooling, some cause surface temperature. Some cause cooling, some cause warming. Which type will increase more??warming. Which type will increase more??

Sea Level changes: Expected to rise as snow/ice melts, Sea Level changes: Expected to rise as snow/ice melts, and is happening now, but some regions will see increased and is happening now, but some regions will see increased snowfall if planet warms, offsetting some, if not all, of the snowfall if planet warms, offsetting some, if not all, of the sea level risesea level rise

Ocean Currents: Infusion of fresh water alters density, Ocean Currents: Infusion of fresh water alters density, disrupts currentsdisrupts currents

Global Response?Global Response?

Climate change: Gradual or Rapid?Climate change: Gradual or Rapid? Political ForcesPolitical Forces

– Will countries play by the rules after ratifying a treaty? Will countries play by the rules after ratifying a treaty? (Canada)(Canada)

– Should developed countries curtail their emissions and Should developed countries curtail their emissions and let developing nations continue until their emissions let developing nations continue until their emissions become “substantial?”become “substantial?”

– Should developing nations be denied the chance the Should developing nations be denied the chance the U.S. and other developed nations had?U.S. and other developed nations had? No, it’s only fair. We can’t stifle their developmentNo, it’s only fair. We can’t stifle their development Yes, we know more today about what we’re doing to the planetYes, we know more today about what we’re doing to the planet

– Then, should developed nations cover the increased cost developing Then, should developed nations cover the increased cost developing nations will incur to meet stricter environmental guidelines? After all, we nations will incur to meet stricter environmental guidelines? After all, we screwed it up in the first place.screwed it up in the first place.

What do ya’ll think? What do ya’ll think?

Is this just liberal fear-mongering BS?Is this just liberal fear-mongering BS? Something you’re concerned about?Something you’re concerned about? Something you’re willing to sacrifice for to Something you’re willing to sacrifice for to

deal with? (higher energy prices, etc.)deal with? (higher energy prices, etc.)