50900document32056Biophysical and economic limits to negative co2 emissions.pdfapplication/pdf8c3537799971bd57c0b42bfda2af5799MD511070582016-01-25 07:37:24https://pure.iiasa.ac.at/id/eprint/11704/1/Biophysical%20and%20economic%20limits%20to%20negative%20co2%20emissions.pdf