Dr. George Hurtt Department of Natural Resources &

Dr. George HurttDr. George Hurtt

Department of Natural Resources &Department of Natural Resources &

Institute for the Study of Earth, Oceans Institute for the Study of Earth, Oceans and Spaceand Space

University of New HampshireUniversity of New Hampshire

Durham, NH 03824Durham, NH 03824

george.hurtt@unh.edugeorge.hurtt@unh.edu

November 6, 2003

NAST 2001

IPCC 2001

IPCC 2001

Global C Budget (PgC/y)Global C Budget (PgC/y)

1980s1980s 1990s1990s

Atm. IncreaseAtm. Increase 3.3+/-0.13.3+/-0.1 3.2+/-0.13.2+/-0.1

EmissionsEmissions 5.4+/-0.35.4+/-0.3 6.3+/-0.46.3+/-0.4

Ocean-Atm. FluxOcean-Atm. Flux -1.9+/-0.6-1.9+/-0.6 -1.7+/-0.5-1.7+/-0.5

Land-Atm. Flux*Land-Atm. Flux* -0.2+/-0.7-0.2+/-0.7 -1.4+/-0.7-1.4+/-0.7

*partitioned as *partitioned as followsfollows

Land UseLand Use 1.7(0.6-2.5)1.7(0.6-2.5) NANA

Residual Residual Terrestrial SinkTerrestrial Sink

-1.9(-3.8-0.3)-1.9(-3.8-0.3) NANA

IPCC 2001

IPCC 1994

IPCC 2001

Transport Numbers of RegionsModels 7 12 17

TM2

TM3

GCTMM

Pacala et al., 2001, Science, 292:2316-2320

Land-Based Range

}

-0.5

0

0.5

1

1.5

1990-1994

I II III

Consistent land- and atmosphere- based U.S. carbon Consistent land- and atmosphere- based U.S. carbon sink estimates.sink estimates.

Category Low High

Forest Trees 0.11 0.15  Other Forest Organic Matter 0.03 0.15  

Cropland Soils 0.00 0.04  Woody Encroachment 0.12* 0.13*

 Wood Products 0.03 0.07  Reservoirs 0.01 0.04  

Exports Minus Imports 0.04 0.09  

Exported by Rivers 0.03 0.04

Apparent Sink Without WoodyEncroachment 0.25 0.58  

Apparent Sink 0.37 0.71

Sink 0.30 0.58

Projecting the Future of the U.S. Carbon SinkProjecting the Future of the U.S. Carbon Sink

Hurtt et al., 2002, Proceedings of the National Academy of Sciences, 99(3):1389-1394

Cox et al., 2000, Nature 408:184-187

Coupled Earth System ModelsCoupled Earth System Models

Context for decision making with uncertainty

Kammen & Hassenzahl, 1999, Should We Risk It?, Princeton.

Kammen & Hassenzahl, 1999, Should We Risk It?, Princeton.

Context for decision making with uncertainty