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GLOBAL WARMING. Johan C. Varekamp Earth & Environmental Sciences Wesleyan University Middletown CT. Structure of this presentation 1. Global Warming-real or not? 2. Climate science, models and predictions. Source: OSTP. Variations of the Earth’s Surface Temperature*.

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Presentation Transcript
slide1

GLOBAL WARMING

Johan C. Varekamp

Earth & Environmental Sciences Wesleyan University

Middletown CT

slide2
Structure of this presentation1. Global Warming-real or not?2. Climate science, models and predictions
slide5

Variations of the Earth’s Surface Temperature*

*relative to 1961-1990 average

Source: IPCC TAR 2001

slide6

The Exploration of the West: Conditioned by climate change?

Vikings

(Eric the Red)

da Verrazano

Columbus

Hudson, Block

Boston Massacre

slide7

Collapse of the Larsen

Ice Shelf near Antarctica

- a piece of ice the size of

Rhode Island came adrift

slide11

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”?

slide13

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

slide14

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 h 2 o co 2 ch 4 n 2 o o 3 cfc

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

CHANGES IN THE CONCENTRATIONS OF THE GREENHOUSE GASES OVER TIME?

slide17

Deforestation

Source: OSTP

slide18

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??

slide20

Clear correlation between atmospheric CO2 and temperature over last 160,000 years

  • Current level of CO2 is outside bounds of natural variability
  • Rate of change of CO2 is also unprecedented

Source: OSTP

slide21

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

    • CO2 concentrations will likely be more than 700 ppm by 2100
    • Global average temperatures projected to increase between 2.5 - 10.4°F (1.4 - 5.8 oC)

2100

Source: OSTP

slide22

MUCH OF THE CO2 EMITTED INTO THE ATMOSPHERE DOES NOT STAY THERE - TAKEN UP BY PLANTS AND DISSOLVES IN THE OCEANSTHE CARBON CYCLE!

how do we model future atmospheric co 2 concentrations
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
  • Population growth rates
  • Economic growth
  • Switch to alternative energy technologies
  • Sharing of technology with the developing world
slide25

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

Symbols:

Mx = mass of carbon

Kx = rate constant

FFF = Fossil Fuel Flux of

Carbon

Feedbacks:

Bf = Bioforcing factor;

depends on CO2(atm)

K4 = f(temperature)

slide27

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

The common approach is: DTs = lDForDF/DTs = 1/l where

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

DTs is the change in the surface temperature of the earth

We can solve for l by taking the first derivative of the ‘greenhouse modified’ Boltzman’s Law F = t sTs4 or dF/dTs = 4F/Ts

leading to a l 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.

temperature projections tar
Temperature Projections (TAR)
  • 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

Source: IPCC TAR 2001

slide37

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
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!
slide39

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.

slide40

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

slide42

Could these be related?

Greenhouse surprises

and unexpected events

slide43

Evidence for very

rapid climate change

in the past:

Younger Dryas

cold period

slide45

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
slide46
Environmental Issues in LISCoastal Salt Marsh DegradationSeasonally Hypoxic Bottom WatersMetal PollutionEcosystem Shifts
slide53

137Cs

Chestnut blight

210Pb

Onset of hatting

industry

Ragweed pollen

14C

slide56

RSLR curves, CT coast

V+T, unpub data

tar sea level rise projections
TAR Sea-Level Rise Projections
  • 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

Source: IPCC TAR 2001

slide58

Long Island Sound has suffered

  • from hypoxia for decades:
  • Result of Global Warming?
  • Eutrophication?
  • It has always been like this…...
slide59

EAST LIS

CENTRAL LIS

WEST LIS

NARROWS

slide66

MEASURES OF ORGANIC PRODUCTIVITY:

  • BURIAL RATE OF ORGANIC CARBON
  • BURIAL RATE OF DIATOM “SKELETONS” (BIOGENIC SILICA)
  • PRODUCTION RATE OF HETEROTROPHS LIKE FORAMINIFERA
paleo temperature calculations from mg ca in foram tests

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

slide71

Core A1C1

MWP

LIA

MGW

slide72

WET

DRY

slide74

The d13C* value indicates the amount of oxidized Corg that was added to the bottom water column.

The d13C* value serves as an indirect proxy for OCI or Oxygen Consumption Index (Level of Paleo Oxygenation)

observations

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

slide80

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
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
CONCLUSIONS (2)

IMPACTS ON LIS:

  • 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
conclusions 3
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
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 productivity==> more Corg
    • Modern global warming==> higher rate of Corg decompositon and increased water stratification

HYPOXIANEED A COMBINATION OF HIGH BWT AND HIGH Corg LOADING

slide85

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.

slide86

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