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G-Cubed: Geochemistry, Geophysics, Geosystems

 

Keywords

  • global warming
  • greenhouse forcing
  • leakage
  • natural gas

Index Terms

  • 3305 - Climate change and variability

Paper in Press

GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, doi:10.1029/2012GC004032

Assessing the greenhouse impact of natural gas

Key Points
  • Natural gas substitution achieves 40% warming reduction of low carbon fuels
  • Duration of substitution does not affect 40% benefit
  • Full benefit at gas leakage 1% of production or less

Author:

Lawrence Cathles

The global warming impact of substituting natural gas for coal and oil is currently in debate. We address this question here by comparing the reduction of greenhouse warming that would result from substitution of gas for coal and oil to the reduction which could be achieved by immediately substituting low carbon energy sources. This comparison shows that if the leakage rate of natural gas is ~1% or less the substitution of natural gas reduces global warming by 40% of that which could be attained by the immediate transition to low carbon energy sources. This 40% benefit does not depend on the duration of the transition period; it is the same whether the transition is over 25 or 100 years. The comparison avoids complexities of SO2 and CO2 removal from the atmosphere, and illustrates clearly that at low gas leakage rates the greenhouse warming from the use of fossil fuels is associated solely with the amount of CO2 introduced into the atmosphere: the less CO2, the less warming. Fast transitions to low carbon energy sources reduce greenhouse gas forcing more because less CO2 accumulates in the atmosphere and are therefore desirable, but the substitution of natural gas is always of substantial benefit if the leakage rates are low because significantly less CO2 is emitted to the atmosphere.

Received 10 January 2012; accepted 14 May 2012.

Citation: Cathles, L. (2012), Assessing the greenhouse impact of natural gas, Geochem. Geophys. Geosyst., doi:10.1029/2012GC004032, in press.