Climate Threat to the Planet:* Implications for Energy Policy and Intergenerational Justice Jim Hansen December 17, 2008 Bjerknes Lecture, American Geophysical Union San Francisco, California *Any Policy-Related Statements are Personal Opinion

Global Warming as a Moral Issue L.D. Danny Harvey Department of Geography University of Toronto

GISS analysis of global surface temperature; 2008 point is 11-month mean.

Surface temperature anomaly relative to base period Left: Anomaly for 2008 meteorological year (December-November). Right: Anomaly for first seven years of this century.

Basis of Understanding 1. Earth’s Paleoclimate History 2. On-Going Global Changes 3. Climate Models (note: modeling #3, but aids other two)

Climate Change Depends on (global, averaged over chaos) 1. Equilibrium Climate Sensitivity 2. Forcings: Human & Natural 3. Response Time (Ocean Inertia)

CO 2, CH 4 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,

(a) CO 2, CH 4 and sea level for past 800 ky. (b) Climate forcings due to changes of GHGs and ice sheet area, (c) Calculated global temperature change based on above forcings and climate sensitivity ¾°C per W/m 2. Observations are Antarctic T change divided by two.

Empirical Climate Sensitivity 3 ± 0.5C for 2 X CO 2 1. I ncludes all fast-feedbacks* * water vapor, clouds, aerosols, surface albedo (Note: aerosol feedback included) 2. Paleo yields precise result 3. Relevant to today’s climate sensitivity generally depends on climate state

Climate Threat to the Planet The Venus Syndrome

Runaway Greenhouse Effect? 1. Unprecedented Speed of +Forcing 2. Negative Feedbacks (e.g. Increased Weathering Rate) of Little Help 3. Solar Irradiance has Increased My Opinion: All Coal  ?? (Runaway Possible) Coal + Tars  !! (Dead Certainty)

Metrics for “Dangerous” Change Extermination of Animal & Plant Species 1. Extinction of Polar and Alpine Species 2. Unsustainable Migration Rates Ice Sheet Disintegration: Global Sea Level 1. Long-Term Change from Paleoclimate Data 2. Ice Sheet Response Time Regional Climate Disruptions 1. Increase of Extreme Events 2. Shifting Zones/Freshwater Shortages

Tipping Point Definitions 1. Tipping Level - Climate forcing (greenhouse gas amount) reaches a point such that no additional forcing is required for large climate change and impacts 2. Point of No Return - Climate system reaches a point with unstoppable irreversible climate impacts (irreversible on a practical time scale) Example: disintegration of large ice sheet

Sea level rise – 20 cm since 1880 Source: IPCC 2007, AR4, WG1

Source: NSIDC, Sea ice extent, Sept 2005 (white) and average extent during the 1980s (pink line)

Source: National Snow and Ice Data Center (NSIDC), USA, Sea ice extent, Sept 2007

Source: NSIDC, Sea ice extent, Sept 2009

Melt descending into a moulin, a vertical shaft carrying water to ice sheet base. Source: Roger Braithwaite, University of Manchester (UK) Surface Melt on Greenland

Jakobshavn Ice Stream in Greenland Discharge from major Greenland ice streams is accelerating markedly. Source: Prof. Konrad Steffen, Univ. of Colorado

Rongbuk Glacier Rongbuk glacier in 1968 (top) and The largest glacier on Mount Everest’s northern slopes feeds Rongbuk River.

Areas of the world dependent on winter snowfall for summer moisture: Shown is the ratio of annual snowfall to annual runoff. The red line outlines the areas where runoff is predominantly from snowmelt and there is not adequate storage to buffer seasonal variations. Source: Barnett et al (2005)

Subtropics expected to expand with global warming. Observations show 4 degrees of latitude expansion. Pier on Lake Mead

Fires Are Increasing World-Wide Source: Westerling et al Western US area burned Wildfires in Western US have increased 4-fold in 30 years.

Coral Reef off Fiji (Photo: Kevin Roland) Stresses on Coral Reefs

Source: Nature 442, (2006)

Assessment of Target CO 2 Phenomenon Target CO 2 (ppm) 1. Arctic Sea Ice Ice Sheets/Sea Level Shifting Climatic Zones Alpine Water Supplies Avoid Ocean Acidification  Initial Target CO 2 = 350* ppm *assumes CH 4, O 3, Black Soot decrease

Target CO 2 : < 350 ppm To preserve creation, the planet on which civilization developed

Initial Target CO 2 : 350 ppm Technically Feasible (but not if business-as-usual continues) Quick Coal Phase-Out Critical (long lifetime of atmospheric CO 2 ) (must halt construction of any new coal plants that do not capture & store CO 2 )

Damage-control Scenarios

Figure 1.5 Business as usual Change in Global Mean Temperature in the context of observed or inferred past variations

The Challenge We can avoid destroying creation! (+cleaner planet, + good jobs!) We have to figure out how to live without fossil fuels someday… Why not now?

Carbon Tax & 100% Dividend 1. Tax Large & Growing (but get it in place!) - tap efficiency potential & life style choices 2. Entire Tax Returned - equal monthly deposits in bank accounts 3. Limited Government Role - keep hands off money! - eliminate fossil subsidies - let marketplace choose winners - change profit motivation of utilities - watch U.S. modernize & emissions fall!

Intergenerational Conflict Intergenerational inequity and injustice is the result, affecting the young and unborn. ‘Did not know’ defense of prior generations no longer viable. Ethical and legal liability questions raised by actions that deceived the public. Continued failure of political process (not even available to young and unborn) may cause increasing public protests.

Major Impacts of Concern Sea level rise of 6-12 m over several centuries to a 1000 years or more Increased occurrence of drought Increased water stress in vulnerable regions Species extinction (1/3 to ½ this century) Acidification of the oceans

Moral and Ethical Dimensions The sanctity of life Disproportionate impacts on the most vulnerable (poor people) and on developing countries – those least responsible, and least able to adapt Intergenerational impacts, discounting Imposition of involuntary risk on others

What Will it Take? Stabilization of the human population at the lowest possible level (i.e., 8 billion instead of 10 billion or more) An end to the growth-for-the-sake-of-growth paradigm Massive emphasis on energy efficiency and conservation (an efficiency and sufficiency ethic) Massive acceleration in the deployment of renewable energy sources

Personal Decisions with Moral Implications Use of energy (especially concerning transportation, home heating and cooling, energy-intensive conveniences) Levels of consumption (how much “stuff” are you buying?) The amount of meat in your diet The levels of convenience and comfort that you demand

Moral Behaviour is To be happy with less To consume less To tread as lightly as possible on the planet To make “sacrifices” cheerfully (Ghandi)