date: Tue, 17 Apr 2001 16:03:44 -0600 from: Jorge Sánchez Sesma subject: Cooperation in climate reconstruction using proxy records. to: tswetnam@ltrr.arizona.edu, katie@ltrr.arizona.edu, dstahle@comp.uark.edu, k.briffa@uea.ac.uk Dear Drs. Swetnam, Hirschboeck, Stahle and Briffa: Enclosed please find the manuscript "Carbon dioxide (CO2) reconstructed records over the past 10,000 years (10Ky)" by A. A. Aldama, F. J. Sánchez-Sesma and myself. It has been submitted to be considered for publication in the section Letters to Nature. I am sending this work to your kind attention, because it takes into account data obtained in your labs or published results of previous studies about climate reconstruction based on tree-rings. The manuscript presents analysis and synthesis of the most important information regarding carbon dioxide for the last 10 thousand years, using calibrated proxy records to reconstruct the CO2 record and its range of variation as well. The results obtained therein strongly suggest: a) A significant reduction, around 25%, of the previous estimate for the anthropogenic contribution of CO2 during the last centuries, b) Larger variations of CO2 during the last thousand years than previous estimates, c) Significant lags between sea level variation and CO2. I would like to know your opinion, coments and suggestions in the final version and also to stablish a formal cooperation in this amazing subject. For your information I am writing a paper about Global Temperature based on proxy records with very interesting results. When it will be finished I will send you a copy. Regards. JORGE SANCHEZ-SESMA (PD. please send me a confirmation message.) INSTITUTO MEXICANO DE TECNOLOGIA DEL AGUA COORDINACIÓN DE HIDROLOGÍA PASEO CUAUHNAHUAC 8532 PROGRESO, JIUTEPEC, MORELOS 62550 MEXICO TELS 52 (7)319-4000 X 775 FAX 52 (7)319-3901 E-MAIL: jsanchez@tlaloc.imta.mx WEBPAGE http://nimbus.imta.mx Attachment Converted: "c:\eudora\attach\sanchez-sesma_CO2_lett_nature.doc"