Global net emissions of carbon dioxide

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Global net emissions of carbon dioxide will have
to go to zero
Pieter P. Tans Earth System Research
Laboratory National Oceanic and Atmospheric
Administration
Greenhouse gases Mitigation and
utilization Kingston, Ontario, 10 July 2007
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HUMANS HAVE CAUSED GREENHOUSE GASES TO INCREASE
Fossil fuel data CDIAC
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HUMANS HAVE CAUSED GREENHOUSE GASES TO INCREASE
Sources Etheridge (JGR 1996) ESRL
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HUMANS HAVE CAUSED GREENHOUSE GASES TO INCREASE
Cumulative fossil fuel emissions (Jan. 2007) 328
25 GtC (source CDIAC)
Observed atmospheric increase (Jan.
2007) 214 8 (source ESRL) Observed ocean
increase through 1994 118 19 (Sabine et
al., Science 2004) oceans,
model-extrapolated through 2006 147
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Sources Siegenthaler et al, Science (2005)
Petit et al., Nature (1999) NOAA/ESRL
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HOW FAR COULD WE PUSH THE CLIMATE?
Pre-industrial atmosphere 600 billion ton C
as CO2 . Until now we have burned 330
billion ton C. Atmosphere increased from 600
to 810 billion ton.
Coal resources 4000-8000 billion ton C
Oil and gas resources 500-1000 billion ton C
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HOW FAR COULD WE PUSH THE CLIMATE?
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HOW FAR COULD WE PUSH THE CLIMATE?
CO2(g) CO2(aq)
Ko (solubility) CO2(aq) H2O H
HCO3 - K1 (first diss. constant) HCO3 -
H CO3 K2
(second dissociation) K1 / K2 HCO3 - 2 /
(CO2(aq) CO3 ) CO2(aq) H2O CO3 2
HCO3 Charge balance 2CO3 HCO3
Na K 2Mg2 2Ca2

Cl 2SO2 Br
Dissolution of solid carbonates (Ca/Mg)CO3
Ca2/Mg2 CO2
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HOW FAR COULD WE PUSH THE CLIMATE?
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HOW FAR COULD WE PUSH THE CLIMATE?
HEATING OF THE SURFACE BY CO2
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HOW FAR COULD WE PUSH THE CLIMATE?
emissions required to match Mauna Loa record
exactly
required emissions to keep atmosphere constant at
390 ppm after 2010
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POTENTIAL SURPRISES - CLIMATE CHANGE OUT OF
CONTROL?
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POTENTIAL SURPRISES - CLIMATE CHANGE OUT OF
CONTROL?
Melting permafrost
Photo Geological Survey of Canada
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Conclusions Human activities are the cause of
increasing greenhouse gases. If we want to avoid
massive, and accelerating, climate change we
have to greatly reduce net CO2 emissions,
eventually to zero. Science cannot provide at
this time with confidence a safe atmospheric
CO2 level that we should try not to exceed.
The risks of dramatic climate change will
increase with continuing emissions.
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HOW FAR COULD WE PUSH THE CLIMATE?
observed increase
emissions equal zero from 2010