Global Warming: How Can We Avoid Dangerous Climate Change?*

Conversation at NARUC

Jim Hansen

16 July 2007

New York

*Any statements relating to policy are personal opinions

Status of the Matter1. A Knowledge Gap - What is Understood (scientists) - What is Known (public/policymakers)

2. The Climate Crisis- Climate Inertia Pipeline Effect- Positive Feedbacks Predominate

Danger:Tipping PointDifferent Planet

3. Good News in Bad News: Opportunity- Must Keep CO2 & Pollution Low- + Health, Agriculture, Environment!

60 50 40 30 20 10 0

Time (Ma)

5

Global deep-sea foraminifera 18O isotope records from 40 sites. 

Temperatures apply to ice-free state, i.e., before Antarctic glaciation (~35 Mybp).

Dashed blue bars are times of ephemeral ice or ice sheets smaller than at present.

Solid bar indicates ice sheets of modern or greater size.

Jakobshavn Ice Stream in Greenland

Discharge from major Greenland ice streams is accelerating markedly.

Source: Prof. Konrad Steffen, Univ. of Colorado

Mt. Graham Red Squirrel

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 (p

pm

v)

600

400

200

100

300

0

500

*Oil & gas from EIA

**Unconventional oil & gas; uncertain, could be large

Other

MethaneHydrates

Shale Oil

Tar Sands

? **

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