INCREASING THE TEMPORAL AND SPATIAL RESOLUTION OF

FOSSIL-FUEL CARBON EMISSIONS ESTIMATES FOR THE

UNITED STATES OF AMERICA

T. J. Blasing Oak Ridge National Laboratory

Christine Broniak, Oregon State University

Gregg Marland, Oak Ridge National Laboratory

Sponsor: U.S. Department of Energy, Office of Science, Biological & Environmental Research

Improved temporal and spatial resolution of fossil-fuel carbon emissions to the atmosphere (as CO2) can improve the accuracy of carbon-cycle models.

Temporal resolution to accommodate annual (and daily) cycles in photosynthetic activity

Spatial resolution to capture atmospheric CO2 gradients downwind of large source areas (e.g., large cities and coal-fired power plants)

Previously, atmospheric emissions of fossil-fuel carbon had only been given on an annual basis.

USA totals from Marland, Boden & Andres onCDIAC website

•Finer scales not available for some countries

•Useful for comparing countries & tracking national emissions trends

•Updated through 2002

By 2009 meeting (for USA):

Temporal resolution will capture the daily cycle

Spatial resolution will capture CO2 gradients around large sources (e.g. cities, coal-fired power plants)

Data assimilation results need to be aggregated and checked against emissions estimated directly from fossil-fuel consumption.

For the USA, (~ 23% of global fossil fuel carbon emissions) we have increased the spatial and temporal resolution of fossil-fuel based emissions estimates.

Monthly values: 1981-2004

•Annual range ~ 20% of annual mean•Shape of annual pattern is changing.

USA monthly fossil-fuel carbon emissions

020406080

100120140160

Jan-

81

Jan-

83

Jan-

85

Jan-

87

Jan-

89

Jan-

91

Jan-

93

Jan-

95

Jan-

97

Jan-

99

Jan-

01

Jan-

03

Em

issi

ons

(Tg)

Coal Oil Gas Total

Monthly carbon emissions from fossil-fuel combustion in the USA

0102030405060

Jan-

81

Jan-

83

Jan-

85

Jan-

87

Jan-

89

Jan-

91

Jan-

93

Jan-

95

Jan-

97

Jan-

99

Jan-

01

Jan-

03

C em

issi

ons

(Tg)

Coal Oil Gas

Shape of annual pattern is changing• Since early 1980’s, annual range has shrunk by 4Tg • August-May difference had increased by 5 Tg• Population projections suggest these trends will continue

Average USA fossil-fuel carbon emissions

90

100

110

120

130

140

150

1 2 3 4 5 6 7 8 9 10 11 12Month -- scaled for number of days in month

Em

iss

ion

s (

Tg

)

1981-1985 2000-2004

Monthly estimates of δ13C in fossil-fuel carbon emissions were also calculated

Monthly values of delta 13C in USA fossil-fuel carbon emissions

-31.5

-31.0

-30.5

-30.0

-29.5

-29.0

-28.5

-28.0

-27.5

Jan-

81Ja

n-82

Jan-

83Ja

n-84

Jan-

85Ja

n-86

Jan-

87Ja

n-88

Jan-

89Ja

n-90

Jan-

91Ja

n-92

Jan-

93Ja

n-94

Jan-

95Ja

n-96

Jan-

97Ja

n-98

Jan-

99Ja

n-00

Jan-

01Ja

n-02

Jan-

03Ja

n-04

Date

Delt

a 1

3 C (

per

mil

, fr

om

PD

B)

13C concentrations in atmospheric CO2 are declining as the fossil-fuel fraction increases.

Monthly values of delta 13C in USA fossil-fuel carbon emissions

-31.5

-31.0

-30.5

-30.0

-29.5

-29.0

-28.5

-28.0

-27.5

Jan-8

1Jan-8

2Jan-8

3Jan-8

4Jan-8

5Jan-8

6Jan-8

7Jan-8

8Jan-8

9Jan-9

0Jan-9

1Jan-9

2Jan-9

3Jan-9

4Jan-9

5Jan-9

6Jan-9

7Jan-9

8Jan-9

9Jan-0

0Jan-0

1Jan-0

2Jan-0

3Jan-0

4

Date

Delt

a 1

3 C (

per

mil

, fr

om

PD

B)

Mauna Loa data from Keeling, Bollenbacher and Whorf.

012345

1960 1970 1980 1990 2000

Total Coal Oil Gas

036912

1960 1970 1980 1990 2000

Total Coal Oil Gas

State-by-state per capita emissions(Mg/person) show effects of socio-political-economic factors

California New Mexico

Per capita carbon emissions by State

(Mg/person)

(Year 2000)

• Apportioning national value by population is inaccurate,

• Coal rich states with low populations show highest value,

• National plan is needed for carbon reductions,

• Spatial diversity has increased over time.

Spatial variance of per-capita carbon emissions has increased

0123456

1960

1963

1966

1969

1972

1975

1978

1981

1984

1987

1990

1993

1996

1999

Sta

nd

ard

dev

iati

on

(M

g/p

erso

n)

TOTALCOALOILGAS

Standard deviations of per-capita carbon emissions over the lower 48 states

• Finer temporal/spatial breakdown of fossil-fuel carbon-emissions can improve accuracy of C-cycle models.

• Ultrafine scale emissions estimates based on data assimilation procedures should be aggregated and checked with “ground truth” estimates obtained from fossil-fuel consumption data.

• Greater resolution provides insights about dynamics and trends.

• The spatial breakdown of the data poses a challenge for trying to use per capita emissions as a measure of equity or to provide mitigation targets.