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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*. - PowerPoint PPT Presentation
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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
-34.00
-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)
200
300
400
500
600
700
800
900
1000
1100
1200
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.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
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
1600
1650
1700
1750
1800
1850
1900
1950
2000
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)
2000180016001400120010008006.5
7.0
7.5
8.0
8.5
9.0
d15N
8.5
8.0
7.5
7.0
Core A1C1
year, AD
d15N
20001800160014001200100080010
100
1000
10000C. perf
C. perfringens, nr/gr
2000180016001400120010008000
100
200
300
400
500Hg, ppb
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)
-3.50
-3.00
-2.50
-2.00
-1.50
-1.00
-0.50
0.00
-73.80 -73.30 -72.80 -72.30
Longitude
d13C* per mille
1996/1997
1961 Buzas
Linear(1996/1997)Linear (1961Buzas)
New York
New London
MWP
% organic Carbon and 13C*
2000180016001400120010008001.0
1.4
1.8
2.2
2.6
Corg %
Corg %
200018001600140012001000800-5
-4
-3
-2
-1
0d13C*
d13C*
Year AD
CORE A1C1
0
20
40
60
80
100
120
140
160
900 1100 1300 1500 1700 1900
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