can we avoid dangerous climate change_09jan2007
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Global Warming:Can We Avoid
Dangerous Climate Change?
Jim Hansen
09 January 2007
Operation Sierra Storm
Television Meteorologists Conference
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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 PlanetaryScience Letters, 203, 829-843.
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Ice Age ForcingsImply GlobalClimate Sensitivity~ C per W/m2.
Source:Hansen et al., Natl.Geogr. Res. & Explor., 9, 141,1993.
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Global sea level extracted, via a hydraulic model, from an oxygen isotoperecord for the Red Sea over the past 470 kyr (concatenates SiddallsMD921017, Byrd, & Glacial Recovery data sets; AMS radiocarbon dating).Source: Siddall et al., Nature, 423, 853-858, 2003.
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CO2,CH4 and estimatedglobal temperature
(AntarcticT/2in 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.Feedbacks (GHGs & ice area) are the chiefmechanisms for paleo temperature changes.
2.Instigators of climate change include: orbitalvariations, any other small forcings, chaos.
3. Climate on long time scales is very sensitive toeven small forcings.
4.Another ice age cannot occurunless humans
become extinct.5.Humans now control global climate, for better
or worse.
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Climate forcing agents in the industrial era. Effective forcing accounts forefficacy of the forcing mechanism
Source:Hansen et al., JGR, 110, D18104, 2005.
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Climate Forcings Since 1880
Source:Dangerous human-made interference with climate: A GISS modelE study, submitted
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Source:Earth'senergy imbalance:Confirmation andimplications. Science308, 1431, 2005.
(A) Forcings
used to driveclimatesimulations.
(B) Simulatedand observedsurface
temperaturechange.
2 t C Gl b l W i
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21st Century Global Warming
Climate Simulations for IPCC 2007 Report
Climate Model Sensitivity 2.7-2.9C for 2xCO2(consistent with paleoclimate data & other models)
Simulations Consistent with 1880-2003 Observations(key test = ocean heat storage)
Simulated Global Warming < 1C in Alternative Scenario
Conclusion: Warming < 1C if additional forcing ~ 1.5 W/m2
Source:Hansen et al., to be submitted to J. Geophys. Res.
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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 Change1. General Statement2. Droughts/Floods
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Photos Mark Payne-Gill, naturepl.com; 2005 National Geographic Society. All rights reserved.
Armadillos: One of the Surviving Species?
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Arctic Climate Impact Assessment (ACIA)
Sources: Claire Parkinson and Robert Taylor
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Survival of Species
1. Business-as-Usual Scenario- Global Warming ~ 3C- Likely Extinctions ~ 50 percent
2. Alternative Scenario
- Global Warming ~ 1C
- Likely Extinctions ~ 10 percentClimate 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
S f M lt G l d
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Melt descendinginto 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 majorGreenland ice streamsis accelerating markedly.
Source: Prof. Konrad Steffen,Univ. of Colorado
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Greenland Mass Loss From Gravity Satellite
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Location and frequency of glacial earthquakes on Greenland.Seismic magnitudes are in range 4.6 to 5.1.Source: Ekstrom, Nettles and Tsai, Science, 311, 1756, 2006.
Earthquake Locations Annual Number of Quakes*
* 2005 bars capture only first 10 months of 2005
Glacial Earthquakes on Greenland
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Areas Under Water: Four Regions
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Summary: Ice Sheets
1. Human Forcing Dwarfs Paleo Forcingand Is Changing Much Faster
2. Ice Sheet Disintegration Starts Slowlybut Multiple Positive Feedbacks CanLead to Rapid Non-Linear Collapse
3. Equilibrium Sea Level Rise for ~3CWarming (2510 m = 80 feet) Impliesthe Potential for Us to Lose Control
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Simulated precipitation change in response to climate forcings estimated for 1880-2000.
Source: Hansen et al., JGR110, D18104, 2005.
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Expected Precipitation Changes
1. Increased Precipitation- Tropical Rain-Belt over Ocean- Polar Regions
2. Increased Drought in Subtropics- Western United States- Mediterranean Region
BAU Super-Drought in U.S. WestIncreased Fires Scorched Earth
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SST in Pacific Warm Pool (ODP site 806B, 0N, 160E) in past millennium.Time scale expanded in recent periods. Data after 1880 is 5-year mean.Source:Medina-Elizalde and Lea, ScienceExpress, 13 October 2005;data for 1880-1981 based on Rayner et al., JGR,108, 2003, after 1981 on Reynolds and Smith, J. Climate, 7, 1994.
kyr Before Present Date
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Fossil Fuel Reservoirs
and 17502004 Emissions
0
200
400
600
800
1000
1200
1400
Oil Gas Coal
GtC
Reserve growth
Proven reserves*
Emissions (CDIAC)
EIA
IPCC
CO2
(ppm
v)
600
400
200
100
300
0
500
*Oil & gas from EIA
**Unconventional oil & gas; uncertain,
could be large
Other
Methane
Hydrates
Shale
Oil
Tar Sands
? **
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Science & Implications
1. Warming >1C Risks Different Planet- Maximum CO2 ~450 ppm
- Somewhat greater if non-CO2
2. Gas + Oil Use Most of 450 ppm Limit- Coal/unconventional must sequester CO2- Gas + Oil supplies must be stretched
3. 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
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Inferences (Opinions)
1. Building/Vehicle Efficiencies Critical- Needed to Stretch Oil/Gas Supplies- Needed for Future Non-Carbon Energy
2. Both Incentives and Standards Needed- Rising Price on Carbon Drives Innovation- Efficiency Standards Proven Effective
3. United States Leadership Essential- Large Emissions, Tech & Political Leader- Developing Countries cannot be expectedto act until the U.S. Takes First Step
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Fossil Fuel Facts & Opinions1. Value Fossil Fuels >> Mining Cost
- $$$$ Pocketed by Middle East & Russia- Those $$$$ Fund Many Things
2. Steadily Rising Carbon Tax- Can Be Revenue Neutral
- Nonpartisan Tsar Adjusts Rate (a la Fed. Res.)- Spurs Technology Devel. & Efficiency- Energy Need per GDP Decreases
3. Results
- Energy Independence & National Security- $$$$ to U.S. Treasury, not Middle East/Russia- Improves U.S. International Competitiveness- Good High-Tech High-Pay Jobs in the U.S.
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Summary: Is There Still Time?
Older Generation Swampedby Near-term Problems
Need Action Soon: Decade BAU
Eliminates Alternative ScenarioPotential Legacy: Great Moral
Burden, Perhaps a Legal One
Best Hope: Young GenerationBecomes Informed and Involved
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Final Question:
Larry King Has Said: Nobody
Cares About 50 Years From Now
Who Is He Speaking For?
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Ozone Success Story
1.Scientists: Clear warning
2.Special Interests: Denied story for years, butdeveloped ozone-friendly technology
3.Media: Transmitted the message well
4.Public: quick response; spray cans replaced;concern of public was clear to lawmakers
5.Government: U.S./Europe leadership; allow delay& technical assistance for developing countries
Result: No additional CFC-producing infrastructure built
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Global Warming Story
1.Scientists: Fail to clearly distinguishclimate change & BAU = A Different Planet
2.Special Interests: Disinformation campaigns,emphasis on short-term profits
3.Media: False balance, & leap to hopelessness
4.Public: understandably confused, uninterested
5.Government: Aids and abets special interests;fails to lead no Winston Churchill today
Result: CO2 emissions continue to increase at BAU rate
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s it appears that the world may pass a tipping point soon, beyond which it will be
impossible to avert massive future impacts on humans and other life on the planet:Who Bears (Legal/Moral) Responsibility?
1.Scientists?
2.Media?
3.Special Interests?4.U.S. Politicians?
5a.Todays U.S. Public?
5b.U.S. Children/Grandchildren?
Who Will Pay?
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Source:Hansen et al.,J. Geophys. Res.,submitted.
Temperature changeobserved and simulated
for different forcingmechanisms.
Aerosol forcing(negative) is thought tobe slightly excessive inin the all forcingsimulation.
Workshop at East West Center Honolulu
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April 4-6, 2005; Local Host: Intnl. Center for Climate & Society, Univ. Hawaii
Workshop at East-West Center, Honolulu
Air Pollution as Climate Forcing: A Second Workshop
Multiple Benefits by Controlling CH4 and CO(benefits climate, human health, agriculture)
Multiple Benefits from Near-Term Efficiency Emphasis(climate & health benefits, avoid undesirable infrastructure)
Targeted Soot Reduction to Minimize Warming from Planned Reductions ofReflective Aerosols
(improved diesel controls, biofuels, small scale coal use) Targeted Improvements in Household Solid Fuel Use
(reduces CH4, CO, BC; benefits climate, human health, agriculture)
Conclusion: Technical Cooperation Offers Large Mutual Benefits to Developed& Developing Nations.
References:Air Pollution as Climate Forcing: 2002 Workshop; 2005 Workshop http://www.giss.nasa.gov/meetings/pollution02/ and 2005/
U.S. Auto & Light Truck CO2 Emissions
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g 2
Source:On the Road to ClimateStability, Hansen, J., D. Cain andR. Schmunk., to be submitted.
Moderate Action is NRCPath 1.5 by 2015 and
Path 2.5 by 2030.
Strong Action addshydrogenpowered vehiclesin 2030 (30% of 2050 fleet).
Hydrogen produced fromnonCO2 sources only.
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United States annual savings (at $50/barrel, todays dollars) in 2030 for alternativeautomotive efficiency improvements.