Johan C. VarekampEarth & Environmental Sciences Wesleyan

UniversityMiddletown CT

GLOBAL WARMING

Structure of this presentation

1. Global Warming-real or not?2. Climate science, models and

predictions

Source: OSTP

Source: IPCC TAR 2001

Variations of the Variations of the Earth’s Surface Earth’s Surface Temperature*Temperature*

*relative to 1961-1990 average*relative to 1961-1990 average

20001900180017001600150014001300120011001000900-34.50

-34.25

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-33.75

-33.50

Age Years AD

d18O

WARM

COLD

MWP LIA MGW

Hudson, BlockColumbus

Boston Massacre

da VerrazanoVikings(Eric the Red)

The Exploration of the West: Conditioned by climate change?

Collapse of the Larsen Ice Shelf near Antarctica - a piece of ice the size of Rhode Island came adrift

Melting of the Arctic and Antarctic Ice Caps

So these are the data:There is global warming, ice is

melting, glaciers are retreating, rainfall patterns are changing, plants and animal species are “moving”, sea

level is rising.

The real BIG question is:Natural Variability or the “Human Hand”?

THE GREENHOUSE EFFECTTHE SUN EMITS SHORT WAVELENGTH RADIATION (‘VISIBLE LIGHT’) WHICH

PENETRATES THROUGH THE ATMOSPHERE AND HEATS THE SOLID EARTH.

THE SOLID EARTH EMITS LONG WAVE LENGTH RADIATION (‘INFRA RED’) WHICH IS

ABSORBED ‘ON ITS WAY OUT’ BY THE GREENHOUSE GASES.

A THERMAL BLANKET IS THE RESULT

Principles of terrestrial climate:

Incoming solar radiation equals outgoing terrestrial radiation

Rsun = Rterr The magnitude of Rterr depends on Ts (Boltzman Law).

Part of the outgoing terrestrial radiation is blocked by greenhouse gases, and the earth warms up a bit to restore the radiative equilibrium

GREENHOUSE GASES:H2O, CO2, CH4, N2O, O3, CFC

CHANGES IN THE CONCENTRATIONS OF THE GREENHOUSE GASES OVER TIME?

Burning of fossil fuelsBurning of fossil fuels

Source: OSTP

DeforestationDeforestation

Source: OSTP

ANTHROPOGENIC CARBON FLUXES IN THE 1990s:

FOSSIL FUEL BURNING: 6 BILLION TONS CARBON/YEAR

DEFORESTATION: 1.1 BILLION TONS CARBON/YEAR

TOTAL: 7.1 BILLION TONS CARBON/YEAR

WHERE IS ALL THAT CO2 GOING??

Source: OSTP

• Clear correlation Clear correlation between atmospheric between atmospheric COCO22 and temperature and temperature

over last 160,000 yearsover last 160,000 years

• Current level of COCurrent level of CO22

is is outsideoutside bounds of bounds of natural variabilitynatural variability

•RateRate of change of CO of change of CO22

is also unprecedentedis also unprecedented

Source: OSTP

If nothing is done to slow If nothing is done to slow greenhouse gas emissions. . .greenhouse gas emissions. . .

• COCO22 concentrations will concentrations will

likely be more than 700 ppm likely be more than 700 ppm by 2100by 2100

• Global average temperatures Global average temperatures projected to increase between projected to increase between 2.5 - 10.4°F (1.4 - 5.8 2.5 - 10.4°F (1.4 - 5.8 ooC)C)

2100

Source: OSTP

MUCH OF THE CO2 EMITTED INTO THE ATMOSPHERE DOES NOT STAY THERE -

TAKEN UP BY PLANTS AND DISSOLVES IN THE OCEANS

THE CARBON CYCLE!

Missing CarbonPredicted CO2

increase from carbon emission records

How do we model future atmospheric CO2 concentrations?• Apply a carbon cycle model to a range of future

Fossil Fuel Flux scenarios • Use ‘economic scenarios’ that depend strongly on

1. Population growth rates

2. Economic growth

3. Switch to alternative energy technologies

4. Sharing of technology with the developing world

Carbon cycle model from E&ES 132/359 at Wesleyan University

Symbols:Mx = mass of carbonKx = rate constantFFF = Fossil Fuel Flux of Carbon

Feedbacks:Bf = Bioforcing factor; depends on CO2(atm)K4 = f(temperature)

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1850 1900 1950 2000 2050 2100Age

CO2 (atm) ppm

YOHE1

YOHE7

SRESA1

SRESA2

SRESB1

PRESENT FUTURE

THE E&ES 132/359 CARBON CYCLE MODEL

To go from atmospheric CO2 concentration change to climate change, we need to know the climate sensitivity parameter, .

The common approach is: Ts = ForF/Ts = 1/ where

F is the ‘radiative forcing’ caused by the increased CO2 concentration. The value of F can be calculated from the increase in CO2 concentration using an integrated version of deBeers law.

Ts is the change in the surface temperature of the earth

We can solve for by taking the first derivative of the ‘‘greenhouse greenhouse modified’modified’ Boltzman’s Law F = Ts

4 or dF/dTs = 4F/Ts leading to a value of 0.3 K/Wm-2. That value equals 0.27 K/Wm-2 for an earth with similar albedo but no atmosphere (no greenhouse).

This approach is the most fundamental response function and uses zero climate feedbacks! Climate models use 0.3 - 0.9 K/Wm-2, incorporating various positive and negative feedbacks.

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1850 1900 1950 2000 2050 2100AGE

delta T oC

YOHE 1

YOHE7

SRESA1

SRESA2

SRESB1

PRESENT FUTURE

THE E&ES 132/359 CLIMATE MODEL (CO2 only!)

• Global average temperature is projected to increase by 1.5 to 5.8 °C in 21th century

• Projected warming larger than in SAR

• Projected rate of warming is high compared to the climate record

Temperature Projections (TAR)Temperature Projections (TAR)

Source: IPCC TAR 2001

If we continue as we have done for the last 100 years

(business-as-usual scenario), we will be looking at a much

warmer earth, with many unpredictable side effects (sea

level, extreme events, changes in carbon cycle -methane in

tundras, methane in clathrates, etc)

The Kyoto Protocol

• Main aim is to stabilize the concentrations of CO2 and the other GHG in the atmosphere through reductions in carbon emissions

• Direct Goal: reduce carbon emissions by ~ 5 % below 1990 emission levels in 1012

• Uses trading of ‘carbon pollution units’ as an incentive for the economically least painful way

• Net effect would be that atmospheric CO2 concentrations in 2012 would be about 1-2 ppm below non-treaty levels!

141 countries have ratified the treaty (55% of the carbon emissions), with

the big absences in the western world being the USA (20 % of the carbon emissions) and Australia.

Large carbon contributors from the emerging economies (but growing fast!) are China, India and Brazil,

which are exempt from the protocol.

The Kyoto protocol is not the wisdom of scientists nor the folly

of the greens, but shows the courage of progressive

politicians to work on the future of our planet -

one small step at a time

WHICH OF THESE

SYMBOLS WILL BE THE STRONGER

ONE??

Could these be related?

Greenhouse surprises and unexpected events

Evidence for very rapid climate change in the past:

Younger Dryas cold period

The white colours are urban areas: high populationdensity along western LIS

Estuary of National Importance• The Urban Sea – more than 28 million people live within a one-hour

drive from its shores

•LIS contains over 18 trillion gallons of water

•LIS watershed > 16,000 square miles

• LIS is 170 km long, 30 km wide, mean depth 20 m

•A source of food, recreation, and commerce

Environmental Issues in LISCoastal Salt Marsh DegradationSeasonally Hypoxic Bottom WatersMetal PollutionEcosystem Shifts

Regional Issues Eutrophication, Contamination,Invasive Species

Global IssuesClimate Change

SEA LEVEL RISE IN LONG ISLAND SOUND

OVER THE LAST MILLENNIUM

Wheelers Marsh, Housatonic River, Milford, CT

TODAY!

FUTURE??

Credit: Ron Rozsa

Two Connecticut Marshes

Ages of core samples:

• 137Cs, 210Pb

• Pollen records(Europeansettlement,chestnut blight)

• Metal pollution(dated in marshcores by 210Pb)

5004003002001000

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1650

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Hg ppb

years AD, core A1C1

Ragweed pollen

Onset of hattingindustry

Chestnut blight

137Cs

210Pb

14C

Derive age model:

Mean High Water Rise curves (local)

RSLR curves, CT coastV+T, unpub data

• Global average sea level is projected to rise by 10 to 88 cm between 1990 and 2100

• Projected rise is slightly lower than the range presented in the SAR (15 to 93 cm)

• Sea level will continue to rise for hundreds of years after stabilization of greenhouse gas concentrations

TAR Sea-Level Rise ProjectionsTAR Sea-Level Rise Projections

Source: IPCC TAR 2001

Long Island Sound has suffered from hypoxia for decades:

•Result of Global Warming?

•Eutrophication?

•It has always been like this…...

EAST LIS

CENTRAL LISWEST LIS

NARROWS

Core locations for LIS studies

R/V UCONN

Sampling mud

15N (o/oo), C. perfringens (nr/gr), Hg (ppb)

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d15N

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Core A1C1

year, AD

d15N

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C. perfringens, nr/gr

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Hg, ppb

MEASURES OF ORGANIC PRODUCTIVITY:

•BURIAL RATE OF ORGANIC CARBON

•BURIAL RATE OF DIATOM “SKELETONS” (BIOGENIC SILICA)

•PRODUCTION RATE OF HETEROTROPHS LIKE FORAMINIFERA

Elphidium excavatum

Paleo-temperature calculations from Mg/Ca in foram tests:

(Mg/Ca)f = A10BT

•The parameters A and B are empirically fitted with core-top samples to obtain a mean annual modern LIS bottom water temperature of ~12.5 C

•The mixing model suggests that (Ca/Mg)w is not salinity-sensitive in the range of modern LIS salinities

Core A1C1

MWP LIA MGW

DRY WET

The 13C* value indicates the amount of oxidized Corg that was added to the bottom water column.

The 13C* value serves as an indirect proxy for OCI or Oxygen Consumption Index (Level of Paleo Oxygenation)

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Longitude

d13C* per mille

1996/1997

1961 Buzas

Linear(1996/1997)Linear (1961Buzas)

New York

New London

MWP

% organic Carbon and 13C*

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2.6

Corg %

Corg %

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Year AD

CORE A1C1

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Age Years AD

Core A1C1rel T

Observations:•Since 1850 increase in pollutants (Hg), sewage, different N sources, and increased foram productivity•Carbon storage in LIS sediments has increased by ~4-5X in the last 150 years. Higher Corg burial rates in Western LIS compared to Central and East LIS•E-W gradient in BSi: about 2.5 % in Central LIS, up to 4.5 % in WLIS. Biogenic Silica storage also increased over the last 150 years

•Sediment accumulation rates increased several-fold as well==> land use changes

Carbon isotopes became “lighter” since early 1800’s which is mainly the effect of increased organic carbon burdens (and oxidation), minor salinity effects

Hypoxia may have occurred for 200 years but no evidence for hypoxia in central LIS prior to 1800!! Anthropogenic Effect!

Temperature record conform known climate trends

CONCLUSIONS (1):

• Global warming is here! Its effects have been documented extensively worldwide

• The human hand is, according to many, very visible

• Projections for the future are riddled with uncertainties, but all show further warming

CONCLUSIONS (2)

• Paleo-temperature record in LIS since ~900 AD shows MWP, LIA and evidence for MGW

• Highest salinity in LIS occurred during the MWP, lowest during the LIA

• Possibly more salinity variability in the 20th century

IMPACTS ON LIS:

CONCLUSIONS (3)

Major environmental changes in the early 1800’s:increased Corg and Bsi storage, isotopically lighter carbon, lower O2 levels in bottom waters, sewage indicators, changed N sources and metal pollutants

CONCLUSIONS (4)

• Hypoxic events may have occurred since the early 1800’s but were absent before that time. They are severe in the late 20th century. Why? – Enhanced productivityEnhanced productivity==> more Corg

– Modern global warming==> higher rate of Corg decompositon and increased water stratification

HYPOXIAHYPOXIA NEED A COMBINATION OF HIGH BWT AND HIGH Corg LOADING

Work done with funding from the CT SeaGrant College Program, EPA and the CTDEP-administered Lobster Research Fund and efforts by many Wesleyan University students.

The early history of LIS (according to JCV)

Long Island is a moraine pushed up by the glaciers and LIS is a depression sitting in front of that pile of material

When the glaciers started melting (20,000 years BP), LIS filled with fresh water forming Glacial Lake Connecticut

Glacial Lake Connecticut drained around 16,000 years BP and LIS was dry for 1000’s of years

The sea came into LIS around 10,000 years BP

Native Americans settled around 12,000 years BP in CT