Carbon is forever
November 21st, 2008 by Jim Just“The lifetime of fossil fuel CO2 in the atmosphere is a few centuries, plus 25 percent that lasts essentially forever. The next time you fill your tank, reflect upon this.”
So says University of Chicago oceanographer David Archer in his new book The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate.
“The climatic impacts of releasing fossil fuel CO2 to the atmosphere will last longer than Stonehenge. Longer than time capsules, longer than nuclear waste, far longer than the age of human civilization so far.”
The effects of carbon dioxide on the atmosphere drop off so slowly that unless we stop burning fossil fuels we could force Earth out of its regular pattern of freezes and thaws that has lasted for more than a million years.
Archer warns:
“If the entire coal reserves were used, then glaciation could be delayed for half a million years.”
If all recoverable fossil fuels were burnt up, after 1,000 years the air would still hold around a third to a half of the CO2 emissions. For practical purposes, 500 to 1000 years is forever, as the face of the planet would be transformed.
Civilization is adapted to climate zones of the Holocene. As James Hansen and colleagues write in their study Target Atmospheric CO2: Where Should Humanity Aim? (now published in the The Open Atmospheric Science Journal), CO2 levels 450 ppm or larger, if long maintained, would push Earth out of the Holocene past climate tipping points toward the ice-free state, initiating dynamic responses beyond humanity’s control. The Earth’s climate system, because of its inertia, has not yet fully responded to the human-made climate forcings already in the pipeline. If we are to preserve a climate resembling that to which humanity is accustomed, CO2 amount must be reduced to 325-355, if not further.
Hansen draws the energy policy implications of the lasting effects of CO2:
“Because of this long CO2 lifetime, we cannot solve the climate problem by slowing down emissions by 20% or 50% or even 80%. It does not matter much whether the CO2 is emitted this year, next year, or several years from now.”
Bottom line: preservation of the climate of the Holocene requires that most remaining fossil fuel carbon is never emitted to the atmosphere. The only realistic way to sharply curtail CO2 emissions is to phase out coal use except where CO2 is captured and
sequestered.