Carbon Cycle Models Quantify for a Green and Low-Carbon Economy

Abstract

CO2 emissions from the combustion of fossil fuels represent the largest anthropogenic disruption of the natural global carbon cycle and lead to an undesirable increase in atmospheric CO2 levels. The so-called "carbon-neutral" renewable energy source biomass appears to be a promising replacement for fossil fuels. The "Combined Energy and Biosphere Model" (CEBM), was developed as a method for calculating the atmospheric CO2 content after intensive use of biomass. It includes (i) a biosphere part computing the annual cycle of carbon in the biosphere on 2,433 grid elements covering the continents’ plant mass and soil, as well as (ii) an energy economic part for calculating the fossil CO2 emissions of 119 countries. As the history of understanding the carbon cycle (including quantification of plant growth and decay by formulae, inclusion of deforestation, fossil fuel use and the fertilizer effect) shows, such a global carbon cycle model (as the CEBM) provides the needed methodology to assess the net effects of large-scale biomass energy use on the plant’s atmosphere. Results show that biomass (in a systemic view) is “only half as carbon neutral” as previously thought, even on a principal level. The conclusions indicate that (even if biomass is a valuable mitigation strategy) its global potential is limited. When interpreting CEBM scenarios, as a very first priority, reducing the current annual increase in energy demand is most highly needed for preserving climate.