A new paper finds another huge error in the global carbon cycle assumptions used by carbon cycle models such as the highly-flawed IPCC Bern model and as the basis for other models including climate and ocean 'acidification' models. The authors "provide estimates of the climate benefits due to CO2 fertilization of the terrestrial biosphere," finding, "enhanced vegetation growth [from CO2 fertilization] over that period reduced atmospheric CO2 concentration by 85 ppm below what it would have been without that effect, thereby avoiding approximately 0.3°C of warming. This represents a dramatic shift of the carbon budget, by more than 250 billion tons of carbon—more than 30 years of emissions at current rates."
Even more important is the mathematical and observational proof that the effect of CO2 on climate is effectively nil.
Historical Carbon Uptake, Science, 10/25/13
CREDIT: © IPPEI NAOI
The high levels of atmospheric CO2 that have resulted from fossil fuel burning and other anthropogenic activities over the past 150 years are expected to cause increased uptake of carbon by the terrestrial biosphere over the next century, thereby partially offsetting some of the CO2 emissions. This effect is difficult to quantify, though. Deforestation and other land-use changes have transferred great quantities of carbon from the biosphere to the atmosphere since preindustrial times, making the magnitude of carbon uptake by land plants difficult to infer. Shevliakova et al. address this issue with a coupled climate–carbon cycle model study of the terrestrial carbon sink, paying special attention to how land use has changed since the beginning of the industrial revolution. They estimate that enhanced vegetation growth [from CO2 fertilization] over that period reduced atmospheric CO2 concentration by 85 ppm below what it would have been without that effect, thereby avoiding approximately 0.3°C of warming. This represents a dramatic shift of the carbon budget, by more than 250 billion tons of carbon—more than 30 years of emissions at current rates.
Proc. Natl. Acad. Sci. U.S.A. 110, 16730 (2013).
Historical warming reduced due to enhanced land carbon uptake
- Elena Shevliakovaa,
- Ronald J. Stoufferb,
- Sergey Malysheva,
- John P. Krastingb,
- George C. Hurttc, and
- Stephen W. Pacalaa,1
Contributed by Stephen W. Pacala, August 13, 2013 (sent for review December 3, 2012)
Significance
This article provides estimates of the climate benefits due to CO2 fertilization of the terrestrial biosphere. Without these benefits, the atmospheric CO2 concentration would have risen by ∼200 ppm since the preindustrial period instead of the observed ∼115 ppm (an 80% increase), and the global climate would have warmed by an additional 0.31 ± 0.06 °C (a 40% increase). These findings were obtained with a National Oceanic and Atmospheric Administration /Geophysical Fluid Dynamics Laboratory comprehensive Earth System Model ESM2G.
Abstract
Previous studies have demonstrated the importance of enhanced vegetation growth under future elevated atmospheric CO2 for 21st century climate warming. Surprisingly no study has completed an analogous assessment for the historical period, during which emissions of greenhouse gases increased rapidly and land-use changes (LUC) dramatically altered terrestrial carbon sources and sinks. Using the Geophysical Fluid Dynamics Laboratory comprehensive Earth System Model ESM2G and a reconstruction of the LUC, we estimate that enhanced vegetation growth has lowered the historical atmospheric CO2 concentration by 85 ppm, avoiding an additional 0.31 ± 0.06 °C warming. We demonstrate that without enhanced vegetation growth the total residual terrestrial carbon flux (i.e., the net land flux minus LUC flux) would be a source of 65–82 Gt of carbon (GtC) to atmosphere instead of the historical residual carbon sink of 186–192 GtC, a carbon saving of 251–274 GtC.
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