Global Climate Change and the Oceandocuments.coastal.ca.gov/climate/gw-12-2006-barry.pdf• Global...
Transcript of Global Climate Change and the Oceandocuments.coastal.ca.gov/climate/gw-12-2006-barry.pdf• Global...
Global Climate Change and the OceanJames Barry - Monterey Bay Aquarium Research Institute
Global Climate Change and the Ocean
Road Map for Talk• A short climate change introduction
• Carbon dioxide on Earth – the long and short of it
• Global warming and the oceans• Sea level rise• Effects of climate warming on ocean ecosystems
• The high-CO2 ocean and ocean acidification• How does increased ocean carbon affect ocean
ecosystems?• A glimpse of our research at MBARI on ocean
acidification
• Summary
Climate Change during the last 150 million years(Reconstruction from a carbon
cycle model)Tajika, E. (1998) Earth & Planet. Sci. Lett. 160
• CO2 has declined over the past 150 million years
• Up to ~6 x present atmospheric level (PAL) in the past
• ~1 C change in surface T per PAL
Years Before Present (1,000s)0100200300400
Deg
rees
(C)
-12
-8
-4
0
4C
O2
(ppm
)
200
240
280
320
360
400
CO2
Temperature
What is the link between CO2 and Climate?
Ice ages
Millennial Northern Hemisphere CO2 & Temperature
Source: Mann et al. 1999.
Year1750 1800 1850 1900 1950 2000
Atm
osph
eric
CO
2 (p
pm)
260
280
300
320
340
360
380
Car
bon
Emis
sion
s (G
tC/y
)
0
1
2
3
4
5
6
7Atm. CO2 (Ice Core)Atm. CO2 (Moana Loa)Global CO2 Emissions
WW1
WW2
Stocks Crash
1973Oil Embargo
Peak OPECOil Prices
Iraq War 1Poor US Economy
History of CO2 Emissions & Atmospheric CO2 Levels
Years Before Present (1,000s)0100200300400
Deg
rees
(C)
-12
-8
-4
0
4
CO
2 (p
pm)
200
300
400
500
600
700
800
CO2
Temperature
Climate Response
=1.0 - 4.5 oC
perPAL CO2
PAL = PresentAtmospheric
Level
Warming by ~2090
Temperature
Arctic Ice Cover Sept. 2003
Arctic Ice Cover Sept. 1979
Precipitation
Sea Level Rise and Coastal Flooding
Intergovernmental Panel on Climate Change
Sea Level Rise and Coastal Flooding
Intergovernmental Panel on Climate Change
1 m 2 m
4 m 8 m
Societal Impacts: Effects on California
Source: Union of Concerned Scientists- uscusa.org
Global Warming & Ocean Ecosystems
Warming1900 to 2075
Ecosystem Impacts:Coral Reefs
Mass coral bleaching caused by thermal stress1. 95% correlation with increases in sea
temperature (1-2oC above long-term summer sea temperature maxima) and bleaching.
2. Backed up experimentally 3. Basis for a highly predictive SST program at
NOAA (HotSpots):
1. 95% correlation with increases in sea temperature (1-2oC above long-term summer sea temperature maxima) and bleaching.
2. Backed up experimentally 3. Basis for a highly predictive SST program at
NOAA (HotSpots):
1998
2002
Strong, Hayes, Goreau, Causey and others
Threshold temperature –above which bleaching manifests itself (1-2oC above the long-term summer maximum temperatures
WHAT DOES THE FUTURE HOLD?
Hoegh-Guldberg (1999)
Climate-related shifts in rocky intertidal animals (1932-19Warming of water temperatures over 60 years has been accompanied by a shift in the geographic ranges of species
1932 Abundance19
93 A
bund
ance Southern Species
Northern Sp.Cosmopolitan Sp.
Monterey
Warming prediction: Species ranges should migrate poleward with warming temperatures
Southern Species Increased Northern Species Declined
Barry et al. 1995
Changes in Fish Communities in the Channel Islands, California
Conclusions:Northern Species decreasedSouthern Species increased
Are observed changes a response to short-term climate variation or long-term climate warming?
Holbrook et al. 2002
Scale of Oceanographic Variability
3-12 years
~25 years
Centuries+?
Effects of Ocean Warming on Productivity
warm
low growth
Warming increases stratification of the upper ocean, leading to reduced mixing.
In low latitudes, this reduces growth of phytoplankton, which are the base of the food chain
Behrenfeld et al. 2006
Will global warming affect coastal upwelling ecosystems?
• Spring and summer NW winds (alongshore) move water offshore rather than alongshore• Deeper, cooler, nutrient-rich waters ‘up-well’ to the surface• Phytoplankton communities flourish in these high nutrient waters: = high primary production• The food web (zooplankton to whales) benefits from upwelling
Sea Surface Temperature Ocean Color = Phytoplankton
El Nino and Ocean ProductivityEl Nino• Low upwelling• Warm, unmixed waters• Low ocean productivity • Low zooplankton biomass and growth
La Nina• More wind, greater upwelling• Cool, mixed, nutrient-rich waters• Low ocean productivity • Low zooplankton biomass and growth Ocean color = phytoplankton
Zooplankton Biomass
Pacific Decadal Variation in Ocean “Climate”
Chavez et al. 2004
Potential Changes in Sockeye Salmon Distribution from a Doubling of CO2
Sockeye Salmon spend ~2-3 y in the NE Pacific and Bering Sea• Migrate northward in summer, southward in winter• Food availability greatest in summer, but decreases with warmer temperature• Metabolic costs increase exponentially with temperature.• Net intake drops to <0 (beginning starvation) at warmer temperatures
Winter
Summer
7 deg.boundary
now
12 deg.boundary
Welch et al. 1998
now
~2050
-80-60-40
-200
204060
80100120
0 5 10 15 20
Temperature
Ener
gy
Food LevelMetabolic
cost
Net IntakeStarvation ~2050
Potential Changes in Sockeye Salmon Distribution from a Doubling of CO2
Warming of ocean waters will:• Increase metabolic costs • Decrease food levels• Shift optimal feeding areas northward• Increase starvation rates, thereby reducing both individual size and catch• These effects cascade through the entire food chain (i.e. birds & mammals)
Winter
Summer
7 deg.boundary
now
12 deg.boundary
Welch et al. 1998
now
~2050
-80-60-40
-200
204060
80100120
0 5 10 15 20
Temperature
Ener
gy
Food LevelMetabolic
cost
Net IntakeStarvation ~2050
The High CO2 Ocean
Global Carbon Pools & Fluxes
Values in billions of metric tonnes (Gt C/y)
Atmosphere775
Vegetation& Soils2,190
Global PrimaryProduction
& Respiration Fossil Fuels
Deep Ocean38,100
Shallow Ocean = 1,030
Surface Sediments = 150
AvailableFossil Fuels
4,000
0.51.6
6160
90 92
6
Changesin Land
Use
Ocean CO2 “Disposal” Today
Fossil fuel signal has penetrated to >1000 - 2000m.
• The inventory was 48 Pg C in 1994.
• We have disposed of 118 PgC in the world ocean.
• Global surface ocean CO2 disposal is now about 20-25 million tons per day (61 kg/km2)
Sabine et al. (2004)
Range of Reference Case Fossil Fuel Carbon Emissions
Range of all scenarios in the database
0
10
20
30
40
50
60
1900 1920 1940 1960 1980 2000 2020 2040 2060 2080
Range of all scenarios in the database
0
10
20
30
40
50
60
1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100
Glo
bal C
O2
Emis
sion
s (G
tC)
Foss
il &
Indu
stry
Source: IIASA
Median SRES 2100 emission = 14.4 PgC/yOpen literature 2100 emissions ~20 PgC/y
Ocean Carbonate Chemistry
Carbonic Acid Bicarbonate Carbonate
CO2 + H20 H2CO3 HCO3- + H+ CO3
-2 + H+
CO3-2 + Ca2+ CaCO3
CalciumCarbonate
Addition of CO2• Increases acidity• Decreases carbonate ions• Decreases carbonate saturation• Decreases calcification
Future Decrease in Ocean pH
Caldeira and Wickett (2005)
CO2 Air – Sea Exchange
Physiological Stresses Associated with High CO2
Physiological Challenges Respiratory Stress
Reduced pH limits oxygen-binding and transport by respiratory proteins, leading to reduced aerobic capacity.
Acidosis (reduced internal pH)Disruption of acid/base balance impairs function and requires energy to restore or maintain optimal internal pH levels.
Reduced CalcificationDepression in carbonate saturation state increases the difficulty of carbonate deposition, with unknown metabolic consequences
Metabolic Depression (Torpor)Elevated CO2, reduced pH, or both can cause some animals to enter a state of reduced metabolic rate and semi-hibernation
CO2 + H20 H2CO3 HCO3- + H+ CO3
-2 + H+
CO2Carbonic Acid Bicarbonate Carbonate
Air – Sea Exchange
Are CO2-related stresses severe for deep-sea animals?
pH
7.2 7.4 7.6 7.8 8.0 8.2
Dep
th (m
)
0
1000
2000
3000
4000
5000
6000
Central PacificWestern PacificNorth PacificAntarctic PacificEastern Pacific
1. Reduced metabolic rates 2. Reduced enzyme function 3. Evolved in highly stable deep-sea
environment4. Food-limited –
“Living on the edge”
Deep-Sea Animals
Humboldt Squid
pH Variation Among Ocean Basins
Expected Reduction in Coral Reef Calcification due to Reduced Ocean pH
Kleypas et al 1999
Reduced Calcification
Riebesell et al 2000
Normal CO2
High CO2
Pteropod Mollusc
CoralsOcean acidification will effect calcificationfor may species
Clams, Snails, Sea Stars, Urchins, Crabs, Shrimp, Others
The consequences of reduced calcification are not known.
Ocean acidification may affect early life stages more than adults
Impaired development of sea urchin larvae in high CO2 sea water
365 500 1000 2000 5000 10000ppm
7.9 7.8 7.5 7.2 6.8 6.4pH
Kurihara et al. 2004
Tiburon tracks (2000, 2002, 2006)
Deep-sea Corals – Vulnerable to CO2?Deep-sea Corals – Vulnerable to CO2?
MBARI small scale CO2 experiments
CO2 Release System20 liter CO2 pool
ROV Tiburon
RV Western Flyer
Deep-Sea CO2Experiments
CO2 release Time lapse video
Animal cage
Full CO2 corral
Slurp sampler for megafauna
Collecting Megafauna CO2 StationUrchins
Sediment Cores
pH/CTDsensor
Experimental Design
50m
Control
CO2
Controlled-gas Aquarium System for lab-based studies of CO2 tolerance
• Control of temperature, oxygen, carbon dioxide• Use:
• Studies of chronic hypercapnia on marine animals• Growth rates, respiration, physiology
High CO2Low CO2 Average CO2
Nitrogengenerator
GasEx.
CO
2 Ta
nk
O2
Tan
k
Gas Control SystemOxygen , CO2
Regulation
Reservoir: very low O2, CO2
Tank 1 Tank 2 Tank 2 Tanner Crab
Summary of Expected Effects of Ocean Warming
Ocean Warming• Increased stratification of surface waters, reduced primary
productivity, cascading effects throughout the food chain.• Reduced catch for important fishery species• Reduced abundance of marine mammals and birds These phenomena are
known best for short-term events (e.g. El Nino)
• Changes in species distributions, perhaps a disconnect between feeding and breeding grounds
• Warming-related mortality for coral reefs is expected to be severe
• Ocean communities will change with ongoing climate warming, perhaps drastically, but the nature of future ocean ecosystems remains unclear
Summary of Expected Effects of Ocean Warming
• Ocean acidification• Metabolic Stress (respiratory stress, acidosis, reduced
calcification)• Marine calcifiers (from phytoplankton to corals) will be
impaired, with as yet unknown consequences.• Plankton communities will likely change• Water-breathing animals will have higher costs for coping
with CO2-related stress, resulting in lower growth, survival and reproduction• Unclear effects on food webs, but may include a loss of
biodiversity, simplified food webs• Deep-sea organisms are the most sensitive to CO2-related
stress (respiratory stress, acidosis)
• Mitigation of climate warming and ocean acidification is essential