A Paper On The Complexity of Carbon Sequestration To Mitigate Global Warming

A short essay

Pielke Sr., R.A., 2001: Carbon sequestration — The need for an integrated climate system approach. Bull. Amer. Meteor. Soc., 82, 2021.

discussed the complexity of carbon assimilation through deliberate landscape manipulation

A new paper has appeared (and thanks to Timo Hämeranta for again alerting us to such important papers!)

Bala, Govindasamy, K. Caldeira, M. Wickett, T. J. Phillips, D. B. Lobell, C. Delire, and A. Mirin, 2007. Combined climate and carbon-cycle effects of large-scale deforestation. PNAS published online before print April 9, 2007

which provides a detailed confirmation of the complexity of carbon assimilation through deliberate landscape management.

The abstract reads,

“The prevention of deforestation and promotion of afforestation have often been cited as strategies to slow global warming. Deforestation releases CO2 to the atmosphere, which exerts a warming influence on Earth’s climate. However, biophysical effects of deforestation, which include changes in land surface albedo, evapotranspiration, and cloud cover also affect climate. Here we present results from several large-scale deforestation experiments performed with a three-dimensional coupled global carbon-cycle and climate model. These simulations were performed by using a fully three-dimensional model representing physical and biogeochemical interactions among land, atmosphere, and ocean. We find that global-scale deforestation has a net cooling influence on Earth’s climate, because the warming carbon-cycle effects of deforestation are overwhelmed by the net cooling associated with changes in albedo and evapotranspiration. Latitude-specific deforestation experiments indicate that afforestation projects in the tropics would be clearly beneficial in mitigating global-scale warming, but would be counterproductive if implemented at high latitudes and would offer only marginal benefits in temperate regions. Although these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons unrelated to climate.”

The only issue with the excellent research contribution is that the terms “carbon” and “climate” are separated. The paper itself, however, demonstrates that the carbon cycle is part of the climate. That they are “combined” reinforces the need to consider the climate as a system as illustrated, for example, by Figure 1-1 in the 2005 National Research Council Report “Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties“.

The article does make an effective point that “forests remain environmentally valuable resources for many reasons unrelated to climate”. This is why the IPCC and other assessments need to move beyond their narrow focus on the global average radiative forcing of CO2 as the dominant environmental concern.

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