CLIMATE CHANGE Lessons from Earth’s Past

• Main Author: Jeffrey Kiehl
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.397.6663; http://www.cgd.ucar.edu/ccr/aboutus/staff/kiehl/LessonsfromEarthsPast.pdf

fixed in carbonate shells, can help researchers estimate where and how fast the conveyor has moved. Today, it appears that a deepwater parcel that forms in the North Atlantic will reach the southernmost Atlantic after about 1400 “ 14 C years, ” and reach the northeastern Pacific after more than 2200 14 C years; this is equivalent to a deepwater 14 C loss of ~250 per mil (‰). Such old ages and long cycling times are important because they suggest the ocean absorbed, stored, and released vast quantities of carbon in the past. Below 2000-m depth, the gradual aging of modern ocean waters is closely linked to a gradual rise in dissolved CO 2. Today, a 50 ‰ decrease in global deepwater 14 C corresponds approximately to a 7-µmol/kg rise in (natural) dissolved