Plot is from Cao et al, 2011. Zeroing emissions does cause CO2 to drop somewhat, but the climate is not yet in equilibrium with current CO2 levels, so the net effect is roughly constant temperature, all else being equal.
From: geoengineering@googlegroups.com [mailto:geoengineering@googlegroups.com] On Behalf Of Andrew Lockley Sent: Sunday, April 26, 2015 7:54 PM To: John Nissen Cc: geoengineering; Michael Hayes Subject: Re: [geo] Re: Warning over aerosol climate fix - BBC News In theory, I would have thought a rapid drop in CO2 emissions should cause global temperatures to drop pretty quickly, as ocean uptake will remove a lot of historical emissions. You'd have to keep sulphur emissions constant for this to happen, though. Choosing whether to maintain sulphur protection is one of the ways to 'get the camel's nose in the tent', as far as SRM acceptability goes. A On 27 Apr 2015 00:12, "John Nissen" <johnnissen2...@gmail.com> wrote: Hi Michael, I would like to defend Ken on this matter. SRM-type geoengineering is the only kind of intervention which could cool the planet straightaway. We are already cooling the planet with our SO2 emissions associated with coal-fired power stations, but not sufficiently to offset global warming from greenhouse gases. If SO2 emissions were stopped, e.g. because of an economic downturn in China, the planet would warm suddenly; whereas if they were put in the stratosphere they would could cool much more effectively and probably more safely. And if they were put in the stratosphere at mid to high latitude, they might save the Arctic sea ice - the highest priority at present. Cheers, John On Fri, Apr 24, 2015 at 11:25 PM, Michael Hayes <voglerl...@gmail.com> wrote: Hi folks, I find Ken's statement of "The only thing a politician can do to start the planet cooling is solar geoengineering." is un-supportable, on the face of it, as there are a multitude of 'planet cooling' means and methods available. And, the statement ignores roughly every thing that the IPCC (WG3) supports on the mitigation side of the equation. We need to avoid being tethered to a cult of personality and focus upon that which we can do....and do safely. The use of Stratospheric Aerosol (sulfuric acid) Injection is not, under it's current protocol of deployment, safe <https://groups.google.com/forum/#!msg/geoengineering/LJWQD4s2w_U/mVT1_zMxQiUJ> ....And, Ken knows this to be true. Best, Micahel On Friday, April 17, 2015 at 2:16:40 PM UTC-7, andrewjlockley wrote: http://www.bbc.co.uk/news/science-environment-32334528 By Simon Redfern Science writer 16 April 2015 >From the section Science & Environment Any attempts to engineer the climate are likely to result in "different" climate change, rather than its elimination, new results suggest. Prof Ken Caldeira, of Stanford University, presented research at a major conference on the climate risks and impacts of geoengineering. These techniques have been hailed by some as a quick fix for climate change. But the impacts of geoengineering on oceans, the water cycle and land environments are hotly debated. They have been discussed at a meeting this week of 12,000 scientists in Vienna. Researchers are familiar with the global cooling effects of volcanic eruptions, seen both historically and even back into the deep past of the rock record. With this in mind, some here at the European Geosciences Union General Assembly have been discussing the possible worldwide consequences of pumping sulphate aerosols into the stratosphere to attempt to reflect sunlight back into space and cool the planet. Planetary sunshade Two hundred years ago this month, the huge volcano Mount Tambora erupted in Indonesia, throwing tonnes of gas and ash into the stratosphere. Maybe as much as 100 million tonnes of sulphur dioxide aerosols spread as a blanket around the globe, acting like a planetary sunshade. Global temperatures plummeted, and across America and Europe 1816 became known as the year without a summer. Such global cooling processes, but managed in a geoengineering solution, have been touted by some as a possible mechanism to extricate the planet from its path towards a warmer future. Solar radiation management would use stratospheric sulphate aerosols to dim the Sun. Using a variety of climate models, Ken Caldeira, from the Carnegie Institution for Science in Stanford, California, has investigated the likely consequences of such geoengineering on agriculture across the globe. Mount Pinatubo Mount Pinatubo pumped 20 million tonnes of sulphur dioxide high into the sky above the Philippines His research shows that while dimming could rapidly decrease global temperatures, high CO2 levels would be expected to persist, and it is the balance between temperature, CO2, and sunlight that affects plant growth and agriculture. Exploring the regional effects, he finds that a stratospherically dimmed world would show increased plant productivity in the tropics, but lessened plant growth across the northerly latitudes of America, Europe and Asia. It is easy to see how there might be geopolitical shifts associated with changes in regional food production across the globe. "It's probably the poor tropics that stand to benefit and the rich north that stands to lose," said Prof Caldeira. But what if geoengineered sulphate aerosols were, nonetheless, deployed and then a large volcanic eruption like Pinatubo in the Philippines took place? Three such eruptions occurred in the last century so the scenario seems likely. Bad timing Hannele Korhonen, of the Finnish Meteorological Institute, suggests that the climate impacts could be quite unexpected. Her results indicate increased temperatures in the Southern Ocean and in northerly latitudes, as well as the mid-Pacific, but cooling in African and Asian mid-latitudes. Regional weather patterns would still change, as they did after Tambora in 1816, with similar widely felt disruption. "Deploying solar radiation management methods would lead to a completely new climate state with enhanced greenhouse effect and reduced solar radiation," said Korhonen, adding: "There are great uncertainties, related especially to the regional climate impacts of solar radiation management." Commenting on the results, Helene Muri, of the University of Oslo, said: "These modelling experiments have highlighted the new risks associated with solar radiation management. The safest option is, of course, to reduce greenhouse gas emissions and aim for a more sustainable way of living and managing the planet." It is not at all obvious what the other consequences of global geoengineering approaches might be. For example, Patrick Applegate from Pennsylvania State University, reported that solar radiation management may yet fail to prevent sea-level rise from melting ice sheets, which respond on much longer time scales than the temperature effects of solar shielding. Aside from being ineffective in stemming sea-level rise, solar radiation management - according to results from Jerry Tjiputra at Bergen University - would lead to increased ocean acidification in the North Atlantic. These results also suggest that climate engineering could not offer a long-term solution, with the world eventually being in the same place, by 2200, as it would reach without any geoengineering interventions. Asked whether he believed solar radiation management would be deployed, Prof Caldeira responded: "A lot has to do with how bad climate change will end up being. Humans are quite adaptable as a species. "On the other hand, projections for summers in the tropics suggest almost every summer will be hotter than the hottest summer yet on record, associated with crop failures. There is the possibility that there would be widespread crop failures in the tropics in the summer. "The only thing a politician can do to start the planet cooling is solar geoengineering. If a catastrophic outcome does occur, the pressure to deploy a scheme could be overwhelming. "Research into this is an act of desperation on the part of scientists. People see the greenhouse gas concentrations increase and are looking for other ways to reduce environmental risk." -- 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. 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