What would be the sustainable limit for CO 2 emissions?

1. What would be the sustainable limit for CO2 emissions? 18 Jan 2008 R. Shanthini

2. Calculation of Global Sustainable Limiting Rate of Carbon Dioxide Production: 1. Virgin material supply limit:To stabilize the atmospheric CO2 concentration below approximately 550 ppmv by the year 2100, global anthropogenic emissions must be limited to about 7 to 8 x 1015 g (7 to 8 Pg) of C per year (IPCC, 1996). 2. Allocation of virgin material:Each of the average 7.5 billion people on the planet over the next 50 years is allocated an equal share of carbon emissions. This translates to roughly 1 Mg of C equivalents per person per year. Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 18 Jan 2008 R. Shanthini

3. Calculation of Global Sustainable Limiting Rate of Carbon Dioxide Production (contd): 3. Regional “re-captureable” resource base:Recycling of carbon in the form of permanent or semi-permanent sequestration may eventually possible through controversial techniques, not at the moment. 4. Current consumption rate vs. sustainable limiting rate:The U.S. on average produces 6.6 metric tons of C equivalents per person, which is well beyond the global sustainable rate of 1 Mg of C equivalents per person per year. Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 18 Jan 2008 R. Shanthini

4. not updated yet

5. not updated yet Sustainable limit

6. Let’s calculate the sustainable limit for some other material, as well. 18 Jan 2008 R. Shanthini

7. Calculation of Global Sustainable Limiting Rate of Zinc Consumption: 1. Virgin material supply limit:The reserve base for zinc in 1999 was 430 x 1012 g (430 Tg), so the virgin material supply limit over the next 50 years is 430 Tg / 50 years = 8.6 Tg/yr. 2. Allocation of virgin material:Allocating the available zinc equally among all the world’s population gives approximately 8.6 Tg/7.5 billions people = 1.15 kg/(person.yr) Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 18 Jan 2008 R. Shanthini

8. Calculation of Global Sustainable Limiting Rate of Zinc Consumption (contd): 3. Regional “re-captureable” resource base:Assume 30% zinc recycling rate. And, if the system is in steady state and if 30% of the 1.15 kg/(person.yr) is recycled, then each person in the region actually has (1+0.3)(1.15) = 1.5 kg/(person.yr) of zinc available. 4. Current consumption rate vs. sustainable limiting rate:In 1999, the U.S. on average consumed 1.6 Tg for a population of 260 million people, which translates to a U.S. per capita zinc consumption of 6.2 kg/(person.yr). Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 18 Jan 2008 R. Shanthini

9. Calculation of a United States Sustainable Limiting Rate of Germanium Consumption: 1. Virgin material supply limit: 2. Allocation of virgin material: 3. Regional “re-captureable” resource base: 4. Current consumption rate vs. sustainable limiting rate: Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 18 Jan 2008 R. Shanthini