Transcript Document 7388972

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*
*relative to 1961-1990 average
Source: IPCC TAR 2001
The Exploration of the West: Conditioned by climate change?
WARM
Vikings
(Eric the Red)
-33.50
MGW
LIA
MWP
da Verrazano
Columbus
Hudson, Block
d18O
-33.75
-34.00
Boston Massacre
-34.25
COLD
-34.50
900
1000
1100
1200
1300
1400
1500
Age Years AD
1600
1700
1800
1900
2000
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 EFFECT
THE 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 fuels
Source: OSTP
Deforestation
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
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
2100
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)
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!
Predicted CO2
increase from
carbon emission
records
Missing
Carbon
How do we model future
atmospheric CO2 concentrations?
•
•
1.
2.
3.
4.
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
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)
1200
1100
CO2 (atm) ppm
1000
THE E&ES 132/359 CARBON CYCLE MODEL
YOHE1
YOHE7
SRESA1
SRESA2
SRESB1
PRESENT
FUTURE
900
800
700
600
500
400
300
200
1850
1900
1950
2000
Age
2050
2100
To go from atmospheric CO2 concentration change to climate
change, we need to know the climate sensitivity parameter, l.
The common approach is: DTs = l DF or DF/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.
3.0
delta T oC
2.5
THE E&ES 132/359 CLIMATE MODEL (CO2 only!)
YOHE 1
YOHE7
SRESA1
SRESA2
SRESB1
PRESENT
FUTURE
2.0
1.5
1.0
0.5
0.0
1850
1900
1950
2000
AGE
2050
2100
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
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 population
density 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 LIS
Coastal Salt Marsh Degradation
Seasonally Hypoxic Bottom Waters
Metal Pollution
Ecosystem Shifts
Regional Issues
Eutrophication, Contamination,
Invasive Species
Global Issues
Climate 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:
years AD, core A1C1
• 137Cs, 210Pb
• Pollen records
(European
settlement,
chestnut blight)
• Metal pollution
(dated in marsh
cores by 210Pb)
2000
137Cs
1950
1900
Chestnut blight
210Pb
1850
1800
Onset of hatting
industry
1750
1700
Ragweed pollen
1650
1600
0
14C
100
200
300
Hg ppb
400
500
Derive age model:
Mean High Water Rise curves (local)
V+T, unpub data
RSLR curves, CT coast
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
Long Island Sound has suffered
from hypoxia for decades:
•Result of Global Warming?
•Eutrophication?
•It has always been like this…...
EAST LIS
CENTRAL LIS
WEST LIS
NARROWS
Core locations for LIS studies
R/V UCONN
Sampling mud
d15N (o/oo), C. perfringens (nr/gr), Hg (ppb)
Hg, ppb
d15N
500
C. perf
10000
9. 0
d15N
Core A1C1
400 8.5
1000
300 8.0
8. 0
200 7.5
7. 5
100
100 7.0
7. 0
0
800
6. 5
1000
1200
1400
1600
year, AD
1800
10
2000
C. perfringens, nr/gr
Hg, ppb
8. 5
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 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)
-73.80
-73.30
-72.80
New
York
-72.30
New
London
0.00
-0.50
d13C* per mille
-1.00
-1.50
-2.00
-2.50
1996/1997
-3.00
1961 Buzas
-3.50
LongitudeLinear
MWP
% organic Carbon and d13C*
Corg %
d13C*
0
2.6
-1
-2
CORE A1C1
1.8
-3
1.4
1.0
800
-4
1000
1200
1400
Year AD
1600
1800
-5
2000
d13C*
Corg %
2.2
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)
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)
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 productivity==> more Corg
– Modern global warming==> higher rate of
Corg decompositon and increased water
stratification
HYPOXIA 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