What you can’t see- greenhouse gases from the Ocean

Usually, when talking about greenhouse gases, one would think of carbon dioxide, which indeed is very important regarding the Earth climate and human made climate change.

But there are two greenhouse gases, which are actually much stronger than carbon dioxide: Methane, with a warming potential 30 times as strong as carbon dioxide, and nitrous oxide, with a warming potential 270 times as strong as carbon dioxide. Both of them a produced biologically and both are produced, when oxygen is decreasing in the Ocean, as we observe it, these days.

A major focus of our work is and has always been nitrous oxide, which is commonly known as laughing gas, still there is nothing funny about nitrous oxide in these waters:

Some years ago, me, Annette, and later Damian measured nitrous oxide concentrations in the waters off Peru, which were much higher than anywhere else. The reason for this- we believed- was the extreme biological productivity in this region in combination with this huge anoxic zone in deeper waters. The expansion of the oxygen minimum zone off Peru, we think, would lead to even stronger production of nitrous oxide, which then would speed up climate change, again. This would possibly lead to stronger global warming and again oxygen loss from the Ocean and higher nitrous oxide production, which would then be a positive feedback- a vicious cycle.

This time, a team of four people are on board looking at the distribution and production of laughing gas and methane: Damian, Hermann, Mingshuang and Claudia. They took hundreds of samples during this cruise and this time it also looks a bit different: we do for the first time not see those extremely high nitrous oxide concentrations, which may be due to slightly higher oxygen concentrations during this cruise. (The methane samples will be measured when we are back in Kiel.)

Whether this is good or not in terms of climate change, or whether we understood it at all- we don’t know.



Carolin Löscher, SDU/GEOMAR