Handed in on 19

• Main Author: Guido Hirzel
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2007
• Subjects: ice core
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.513.5425; http://www.up.ethz.ch/education/term_paper/termpaper_hs07/Hirzel_rev_termpaper_hs07.pdf

Describing the sinks and sources of nitrous oxide (N2O) in natural systems remains difficult. To some extent it is just impossible or highly speculative as some mechanisms and processes leading to N2O production and con-sumption are still unknown. This paper summarises the actual state of the art of research concerning oceanic N2O emissions and their impact on past abrupt climate changes. The production pathways of oceanic N2O are mainly known. However, their contributions to the overall oceanic emissions remain unclear. The present-day N2O emissions from the ocean and their contribution to the overall emissions have been determined to widely accepted ~4 TgN yr-1. However, it stays unclear how this source evolved over time and how much it contributed to past global emissions. The comparison of the temperature curve of the last glacial and the N2O concentration curve during this time strongly indicates a correlation between these curves. These reconstructions show abrupt climate changes in the northern hemisphere during the last glacial. Oceanic changes in denitrification strength and/or coupled nitrification/denitrification intensity and the resulting N2O emission changes may have enhanced these abrupt changes. The similar pattern of the denitrification signal in sediment cores of the Arabian Sea and N2O ice core records support this thesis. However, knowledge about the influence of the Arabian Sea on these abrupt changes is still vague. In addition, the contribution of oceanic emissions compared to terrestrial N2O emissions remains rather unclear.