status of the matter 1. a knowledge gap - what is understood (scientists)
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Status of the Matter 1. A Knowledge Gap - What is Understood (scientists) - What is Known (public/policymakers) 2. The Climate Crisis - Positive Feedbacks Predominate - Climate Inertia Pipeline Effect Danger:Tipping Point Different Planet. - PowerPoint PPT PresentationTRANSCRIPT
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Global Warming: The Threat to the Planet *
Jim Hansen
17 April 2007
2007 Leo S zilard Lecture
American Physical Society Jacksonville , FL
*Any statements relating to policy are personal opinions
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Status of the Matter
1. A Knowledge Gap - What is Understood (scientists) - What is Known (public/policymakers)
2. The Climate Crisis- Positive Feedbacks Predominate - Climate Inertia Pipeline Effect
Danger:Tipping PointDifferent Planet
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CO2, CH4 and temperature records from Antarctic ice core data Source: Vimeux, F., K.M. Cuffey, and Jouzel, J., 2002, "New insights into Southern Hemisphere temperature changes from Vostok ice cores using deuterium excess correction", Earth and Planetary Science Letters, 203, 829-843.
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Ice Age Forcings Imply Global Climate Sensitivity ~ ¾°C per W/m2.
Source: Hansen et al., Natl. Geogr. Res. & Explor., 9, 141, 1993.
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CO2,CH4 and estimated global temperature (Antarctic ΔT/2 in ice core era)0 = 1880-1899 mean.
Source: Hansen, Clim. Change, 68, 269, 2005.
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Implications of Paleo Forcings and Response
1. Chief mechanisms for paleo climate change GHGs & ice sheet area , as feedbacks .
2. Chief i nstigator of climate change was earth orbital change , a very weak forcing.
3. Climate on long time scales is very sensitive to even small forcings.
4. Human-made forcings dwarf natural forcings that drove glacial -interglacial climate change .
5. Humans now control global climate , for better or worse.
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Proxy record of Plio-Pleistocene (3.5 million years) temperature and ice volume. Based on oxygen isotope preserved in shells of benthic (deep ocean dwelling) foraminifera.
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United Nations Framework Convention on Climate Change
Aim is to stabilize greenhouse gas emissions…
“…at a level that would prevent
dangerous anthropogenic interference with the climate system.”
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Metrics for “Dangerous” Change
Extermination of Animal & Plant Species1. Extinction of Polar and Alpine Species2. Unsustainable Migration Rates
Ice Sheet Disintegration: Global Sea Level1. Long-Term Change from Paleoclimate Data2. Ice Sheet Response Time
Regional Climate Disruptions1. Increase of Extreme Events2. Shifting Zones/Freshwater Shortages
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Arctic Climate Impact Assessment (ACIA)
Sources: Claire Parkinson and Robert Taylor
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Mt. Graham Red Squirrel
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Survival of Species
1. “Business-as-Usual” Scenario- Global Warming ~ 3ºC - Likely Extinctions ~ 50 percent
2. “Alternative” Scenario
- Global Warming ~ 1ºC - Likely Extinctions ~ 10 percent
Climate Feedbacks Scenario Dichotomy
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Increasing Melt Area on Greenland
• 2002 all-time record melt area • Melting up to elevation of 2000 m• 16% increase from 1979 to 2002 70 meters thinning in 5 years
Satellite-era record melt of 2002 was exceeded in 2005. Source: Waleed Abdalati, Goddard Space Flight Center
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Melt descending into a moulin, a vertical shaftcarrying water to ice sheet base.
Source: Roger Braithwaite, University of Manchester (UK)
Surface Melt on Greenland
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Jakobshavn Ice Stream in Greenland
Discharge from major Greenland ice streams is accelerating markedly.
Source: Prof. Konrad Steffen, Univ. of Colorado
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Greenland Mass Loss – From Gravity Satellite
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Areas Under Water: Four Regions
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Summary: Ice Sheets
1. Human Forcing Dwarfs Paleo Forcing and Is Changing Much Faster
2. Ice Sheet Disintegration Starts Slowly but Multiple Positive Feedbacks Can Lead to Rapid Non-Linear Collapse
3. Equilibrium Sea Level Rise for ~3C Warming (25±10 m = 80 feet) Implies the Potential for Us to Lose Control
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Atmospheric CO2 measured at Mauna Loa, Hawaii.
Source: NOAA Climate Monitoring and Diagnostic Laboratory
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CO2 airborne fraction, i.e., ratio of annual atmospheric CO2 increase to annual fossil fuel CO2 emissions.
Source: Hansen and Sato, PNAS, 101, 16109, 2004.
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Fossil Fuel Reservoirs and 1750–2004 Emissions
0
200
400
600
800
1000
1200
1400
Oil Gas Coal
Gt C
Reserve growth
Proven reserves*
Emissions (CDIAC)
EIA
IPCC
CO
2 (ppmv)
600
400
200
100
300
0
500
*Oil & gas from EIA
** Unconventional oil & gas; uncertain, could be large
Other
MethaneHydrates
Shale Oil
Tar Sands
? **
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Status of CO2
Pre-industrial Amount: 280 ppm
Present Amount: 382 ppm
Maximum Allowable ≤ 450 ppm
Rate of Change: +2 ppm/year (and growing)
Maximum Likely To Be Exceeded
‘Geoengineering’ May Be Needed!
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Science & Implications1. Warming >1°C Risks ‘Different Planet’
- Maximum CO2 ~450 ppm (maybe less!)- CO2 limit slightly more, if non-CO2 ↓
2. Quarter of CO2 Stays in Air “Forever”- Eventual Vehicles must be Zero-CO2
(renewable, hydrogen from nuclear or solar, etc.)- Eventual Power Plants must be Zero-CO2
3. Gas + Oil Use Most of 450 ppm Limit- Coal/unconventional must sequester CO2
- Gas + Oil supplies must be stretched
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Methods to Reduce CO2 Emissions1. Energy Efficiency & Conservation
More Efficient TechnologyLife Style Changes
2. Renewable & CO2-Free EnergyHydroSolar, Wind, Geothermal
Nuclear
3. CO2 Capture & Sequestration
No Silver Bullet All Three are Essential
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Outline of Solution
1. Coal only in Powerplants w SequestrationPhase-out old technology. Timetable
TBD
2. Stretch Conventional Oil & GasVia Incentives (Carbon tax) & StandardsNo Unconventional F.F. (Tar Shale, etc.)
3. Reduce non-CO2 Climate ForcingsMethane, Black Soot, Nitrous Oxide
4. Draw Down Atmospheric CO2
Agricultural & Forestry PracticesBiofuel-Powered Power-Plants
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Responsibility for CO2 Emissions and Climate Change