Century scale CO2 pulses could substantially alter marine primary production, CaCO3 export, oxygen concentrations and DMS emissions

<p>The world's oceans have historically made a significant contribution in mitigating global warming by storing both large amounts of anthropogenic CO₂ emissions and a significant portion of the heat generated by the enhanced greenhouse effect. However, precisely because of this buffering function, they are themselves subject to massive chemical and physical regime shifts that are suspected to continue long after anthropogenic CO₂ emissions have ceased. For this reason, within the HORIZON2020-COMFORT project, we are studying the long-term effects that different scenarios of temporarily increasing atmospheric CO₂ concentrations could have on marine biogeochemistry. To this end, we use CLIMBER3alpha+C, an Earth system model of intermediate complexity, to study the response of the ocean carbon cycle and associated nutrients during and after the period of elevated atmospheric pCO₂ levels. Preliminary results show sustained changes in marine primary production, export of CaCO₃, extent of hypoxic zones and production of dimethyl sulfide (DMS), with DMS acting as a condensation nucleus in cloud formation. This raises the possibility that the effects of elevated CO₂ on the oceans will cause a change in both the Earth's radiative balance and the marine carbon pump long after atmospheric CO₂ concentrations have returned to preindustrial levels.</p><p>&#160;</p><p>&#160;</p><p>Acknowledgements:</p><p>&#8220;This project has received funding from the European Union&#8217;s Horizon 2020 research and innovation programme under grant agreement No 820989 (project COMFORT, Our common future ocean in the Earth system &#8211; quantifying coupled cycles of carbon, oxygen, and nutrients for determining and achieving safe operating spaces with respect to tipping points).&#8221;</p><p>&#160;</p><p>Disclaimer:</p><p>&#8220;This [project/poster/presentation/etc.], reflects only the author&#8217;s/authors&#8217; view; the European Commission and their executive agency are not responsible for any use that may be made of the information the work contains.&#8221;</p><p>&#160;</p>