http://www.biogeosciences-discuss.net/bg-2017-235/
Climate engineering and the ocean: effects on biogeochemistry and primary production Siv K. Lauvset1, Jerry Tjiputra1, and Helene Muri2 1Uni Research Climate, Bjerknes Center for Climate Research, Jahnebakken 5, Bergen, Norway 2University of Oslo, Department of Geosciences, Section for Meteorology and Oceanography, Oslo, Norway Received: 06 Jun 2017 – Accepted for review: 13 Jun 2017 – Discussion started: 14 Jun 2017 Abstract. Here we use an Earth System Model with interactive biogeochemistry to project future ocean biogeochemistry impacts from large-scale deployment of three different radiation management (RM) climate engineering (also known as geoengineering) methods: stratospheric aerosol injection (SAI), marine sky brightening (MSB), and cirrus cloud thinning (CCT). We apply RM such that the change in radiative forcing in the RCP8.5 emission scenario is reduced to the change in radiative forcing in the RCP4.5 scenario. The resulting global mean sea surface temperatures in the RM experiments are comparable to those in RCP4.5, but there are regional differences. The forcing from MSB, for example, is applied over the oceans, so the cooling of the ocean is in some regions stronger for this method of RM than for the others. Changes in ocean primary production are much more variable, but SAI and MSB give a global decrease comparable to RCP4.5 (~ 6 % in 2100 relative to 1971–2000), while CCT give a much smaller global decrease of ~ 3 %. The spatially inhomogeneous changes in ocean primary production are partly linked to how the different RM methods affect the drivers of primary production (incoming radiation, temperature, availability of nutrients, and phytoplankton) in the model. The results of this work underscores the complexity of climate impacts on primary production, and highlights that changes are driven by an integrated effect of multiple environmental drivers, which all change in different ways. These results stress the uncertain changes to ocean productivity in the future and advocates caution at any deliberate attempt for large-scale perturbation of the Earth system. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
