asper, 2007 slide 1 lesson #12 the ocean’s future: global warming vernon asper usm

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Asper, 2007 Asper, 2007 Slide Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

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Page 1: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 11

Lesson #12The Ocean’s Future: Global warming

Vernon Asper

USM

Page 2: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 22

• Public awareness of global warming is new

• This is what I grew up believing

• This is the current record

• Perspective is critical

http://en.wikipedia.org/wiki/http://en.wikipedia.org/wiki/Image:Instrumental_Temperature_Record.pngImage:Instrumental_Temperature_Record.png

Page 3: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 33

Global Climate Change• Climate is greatly affected by water masses in

the oceans. The movement of large water masses redistributes heat in the ocean.

• Since the oceans cover 70% of the Earth’s surface, this movement has a major affect on the overlying atmosphere and thus climate.

Page 4: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 44

Global Climate Change• The Greenhouse Effect:

– sunlight penetrates the atmosphere

– it hits the earth and heats it

– heat given off by the earth is trapped by the atmosphere

– some gases are better than others at trapping this heat

http://www.acmecompany.com/stock_thumbnails/13808.greenhouse_effect_2.jpghttp://www.acmecompany.com/stock_thumbnails/13808.greenhouse_effect_2.jpg

Page 5: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 55

• CO2 does affect climate!

http://upload.wikimedia.org/wikipedia/en/d/d2/Atmospheric_CO2_with_glaciers_cycles.gifhttp://upload.wikimedia.org/wikipedia/en/d/d2/Atmospheric_CO2_with_glaciers_cycles.gif

Page 6: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 66

Global Climate Change

• Since we’ve started burning fossil fuels (oil and coal):– the amount of carbon dioxide in the atmosphere has increased

– we can expect temperatures to follow

Page 7: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 77

Global Climate Change• Yes, temperatures are warming!

• Note the scale http://data.giss.nasa.gov/gistemp/graphs/Fig.A.lrg.gif

Page 8: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 88

Global Climate Change (Cont.)

• As temperatures rise, ice will melt glaciers from polar regions

• This would cause sea-level to rise.

Page 9: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 99

• Let’s look back in time• Is this warming new?• Sort of• Note the

cooling

that was

taking

place

for

800 Years!

Page 10: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 1010

The climate record: how we know what we know.

• Ice cores• Sediment cores• Beach profiles• Glacial records

– Scarring, moraines, etc.

– “glacial

erratics”

G. Gaitan VazOperations East Coast II, Marine Wing, Geological Survey of India,41, Kirlampudi Layout, Visakhapatnam 530 017, India

Page 11: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 1111

Ice cores• Greenland and Antarctica

– Record climate records in both hemispheres

– Continuous records back to >400,000 YBP

Page 12: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 1212

Ice core challenges

• Acquisition– Vostok is near the

“south pole of inaccessibility”

– Average temperature

around -50C

• Ice deformation– Compression

– Thinning

– Flow

Page 13: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 1313

Ice core sampling and analysis

• Age– Count layers

• Visual and conductivity which changes seasonally– 14C

• Temperature– Measured directly; insulated well enough to preserve major

features– stable isotopes (next slides)

• CO2, methane, other gases– Air bubbles trapped in snow– Dissolved in water

• Dust from volcanoes– Golden spike to correlate cores– Evidence for large eruptions

Science: Dahl-Jansen et all, 1998

LIA:Little Ice AgeCO: Climateic Optimum

Page 14: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 1414

• So, from historical records, we can look at the recent past……

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Asper, 2007Asper, 2007 Slide Slide 1515

• …..and from ice cores, we can go back 100,000’s of years• LOOK! On this scale, the earth has been cooling for 8,000 years!

Page 16: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 1616

• This record from Greenland shows the temperatures since the last ice age

• Lots of variability

• Abrupt warming 12,000 years ago.

http://math.ucr.edu/home/baez/temperature/http://math.ucr.edu/home/baez/temperature/

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Asper, 2007Asper, 2007 Slide Slide 1717

• This warming caused the sea level rise that we’ve been discussing all semester– Estuaries = drowned river valleys

– Continental shelves

– Relic sedimentshttp://en.wikipedia.org/wiki/Image:Post-Glacial_Sea_Level.pnghttp://en.wikipedia.org/wiki/Image:Post-Glacial_Sea_Level.png

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Asper, 2007Asper, 2007 Slide Slide 1818

• Yes, just 18,000 years ago, there was a LOT of ice around. Most disappeared a very long time ago but some remains

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Asper, 2007Asper, 2007 Slide Slide 1919

• Looking back further, we see that the earth has been cooling steadily for more than 5 million years

• But there are odd oscillations

• Natural oscillations

• Of about 2°C

Page 20: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 2020

•Now lets look WAY back into the earth’s history

•Look how warm it was then!!

•And sea level was higher

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Asper, 2007Asper, 2007 Slide Slide 2121

• The long term temperature story:– Earth’s

colder now than it’s been for most of the last 150 million years!

Page 22: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 2222

Factors affecting climate•Orbital parameters•Sunspots

– More= warmer

– 11 year cycle

•Volcanic eruptions•Tectonics•Carbon dioxide•Methane•Ocean Circulation

http://en.wikipedia.orghttp://en.wikipedia.org

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Asper, 2007Asper, 2007 Slide Slide 2323

• The earth’s orbit isn’t entirely circular– Obliquity

– Precession

– eccentricity

• The tilt changes

• The timing of winter changes

Tilt

Obliquity

Precession

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Asper, 2007Asper, 2007 Slide Slide 2424

`

• Dashed blue = sunlight• Red / blue = temperatures• Remarkable correlation• 5,000 year lag

http://www.roperld.com/graphics/LIAInsolation.jpghttp://www.roperld.com/graphics/LIAInsolation.jpg

Page 25: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 2525

Factors affecting climate•Orbital parameters•Sunspots

– More= warmer

– 11 year cycle

•Volcanic eruptions•Tectonics•Carbon dioxide•Methane•Ocean Circulation

http://en.wikipedia.orghttp://en.wikipedia.org

Page 26: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 2626http://upload.wikimedia.org/wikipedia/commons/c/c2/Vostok-ice-core-petit.png

http://en.wikipedia.org/wiki/Image:Vostok-ice-core-petit.pnghttp://en.wikipedia.org/wiki/Image:Vostok-ice-core-petit.png

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Asper, 2007Asper, 2007 Slide Slide 2727

• Greenland is usually cold, even when the rest of the earth is warm

• It has been warmer over the last 10,000 years than “normal”

• But note the oscillations!!!

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Asper, 2007Asper, 2007 Slide Slide 2828

• The last ice age:

• Temperature and CO2 correlate very well

• Cause and effect?

http://www.clearlight.com/http://www.clearlight.com/~mhieb/WVFossils/~mhieb/WVFossils/last_50k_yrs.htmllast_50k_yrs.html

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Asper, 2007Asper, 2007 Slide Slide 2929

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Asper, 2007Asper, 2007 Slide Slide 3030

Temperature rises first; CO2 follows!

• Warming is FAR more rapid than cooling

• Temperatures warm, then CO2 increases

• Many glitches

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Asper, 2007Asper, 2007 Slide Slide 3131

• But CO2 levels are higher now than they’ve been for 400,000 years

• We “expect” more warming

• But we don’t really know

what caused these fluctuations?

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Asper, 2007Asper, 2007 Slide Slide 3232

Natural CO2 fluctuations

• Sequestration of carbon– Carbon is converted to organic matter and buried

• Release of carbon– Buried carbon is exposed and oxidized

• Geologic outgassing– Natural release of CO2 by the earth

• Weathering of silicate rocks– Weathering removes CO2 from the atmosphere

– Plate motions cause variations in the amount of rocks exposed to weathering

– This is a VERY slow process!

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Asper, 2007Asper, 2007 Slide Slide 3333

Impacts of Warming:

• Warming: ~6°F in next 100 years– Except in Europe where it will be cooler?

• Effects vary regionally: rain, temps • Vulnerable ecosystems: Arctic, alpine• Water supplies?• Food supplies?• Diseases?• Increased forest growth• Damage to coastal infrastructure• Surprises: “significant uncertainties remain?

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Asper, 2007Asper, 2007 Slide Slide 3434

• 1979 and 2003• Arctic sea ice coverage

has been reduced• Many predict an ice-

free Arctic Ocean in a few decades

• This will impact commerce and defense

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Asper, 2007Asper, 2007 Slide Slide 3535

• Climate belts shift• By the year 2095:

– Illinois will have Arkansas winter weather

– Illinois will have Texas summer weather

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Asper, 2007Asper, 2007 Slide Slide 3636

• Melting glaciers and thermal expansion will cause sea level to rise

• this will seriously impact coastal communities

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Asper, 2007Asper, 2007 Slide Slide 3737

• But is this statement true?

http://http://www.sciencedaily.com/www.sciencedaily.com/releases/releases/2005/08/050804123855.htm2005/08/050804123855.htm

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Asper, 2007Asper, 2007 Slide Slide 3838

•Hardly!

•This is a gross exaggeration

•In truth, the temperature in MOST places in Antarctica is decreasing

•But in others, it’s increasing.

•A lot?

•Not 10°C

•Not even in 50 years

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Asper, 2007Asper, 2007 Slide Slide 3939

Recent Ice conditionsRecent Ice conditionsin Antarctica.in Antarctica.Note the huge bergNote the huge berg

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Asper, 2007Asper, 2007 Slide Slide 4040

Global Climate Change(Cont.)

• Global warming may also lead to changes in global wind patterns which may cause changes in ocean currents

• This will:– Alter upwelling and downwelling.

– Alter nutrient availability and productivity.

– Affect migration patterns of marine organisms.

• Affect tropical storms?– Increased shear

– Fewer storms?

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Asper, 2007Asper, 2007 Slide Slide 4141

Deep-Ocean Circulation• Brings heat to the North Atlantic

• Occurs in North Atlantic because of precise salinity and temperature conditions

• If these change and it shuts down, this area will cool dramatically

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Asper, 2007Asper, 2007 Slide Slide 4242

• Remember the “Younger Dryas”?• What caused it?• We think it was the oceans!

http://math.ucr.edu/home/baez/temperature/http://math.ucr.edu/home/baez/temperature/

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Asper, 2007Asper, 2007 Slide Slide 4343

Younger Dryas• Dryas: flower from

Europe– Requires cold climate

• Younger: early part of the period

• Greenland warmed by 15ºF in a decade or less

• Winds: less during colder periods?

• A Global event

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Asper, 2007Asper, 2007 Slide Slide 4444

Younger Dryas• Lasted 1,300

years• Very cold• Atmosphere:

– 3X more sea salt • (wind over oceans)

– 4-7X more dust • (wind over arid places)

• Most likely cause?– Shut down of conveyor circulation!

• Caused by draining of Lake Agassiz• Lake formed from glacial runoff• Ice dam broke, flooding Arctic with fresh water• Recovery required freezing/removal of fresh wter cap

– Comet?

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Asper, 2007Asper, 2007 Slide Slide 4545

Effect of shutting off deep circulation• The north Atlantic would cool• Other areas would warm, especially in the

Southern Hemispherehttp://www.cru.uea.ac.uk/cru/info/thc/http://www.cru.uea.ac.uk/cru/info/thc/

Page 46: Asper, 2007 Slide 1 Lesson #12 The Ocean’s Future: Global warming Vernon Asper USM

Asper, 2007Asper, 2007 Slide Slide 4646

Summary• Climate is complicated; not easily modeled

• The oceans play a huge role

• Climate has changed in the past, is changing now and will change in the future but we don’t know for sure how it will change

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Asper, 2007Asper, 2007 Slide Slide 4747

What should we do?

•  This is for YOU to decide:

• 1) Nothing: just let “nature” take its course

• 2) Nothing, but: give up on limiting CO2 emissions but work on dealing with the impacts

• 3) Encourage developed countries to reduce emissions

• 4) Mandate that all nations reduce emissions

• 5) Use “countermeasures”:– dust blanket

– Umbrella in space

– Pump CO2 into the ocean

– Install “Lovelock” nutrient pumps

– ??