Dear Colleagues, A bunch of us (in forums and communications within the groups in the lists above) have been discussing a potential immediate practical step (that earlier has been raised by others) that may provide at least a modicum of cooling especially over the oceans: *a relaxation of the "bunker fuel" sulfur content regulations that just came into effect in 2020 (https://www.theguardian.com/environment/2020/jan/01/shipping-fuel-regulation-to-cut-sulphur-levels-comes-into-force <https://www.theguardian.com/environment/2020/jan/01/shipping-fuel-regulation-to-cut-sulphur-levels-comes-into-force> ) for inter-port "high seas" shipping. *The idea is that cargo ships and tankers would be able to use the old dirty sulfur laden fuel in the open ocean but switch to the cleaner fuel when they are near ports or human habitation. Apparently many ships have multiple fuel tanks so that they may be able to switch fuels in transit.
*To be clear, we would stress that we fully support getting off of fossil fuels, but if fossil fuels are going to be used anyway it makes no sense not to at least benefit from fossil fuel burning maritime sulfur aerosol generation that is known to have a significant cooling effect *(how much is currently being re-estimated using the "termination shock" signal from the 2020 abrupt change in sulfur emissions due to the regulation). *Looking forward this also points the way to including effective (and hopefully less harmful to human health) tropospheric aerosol generators in future non GHG emitting replacements for the bunker fuel* (see the HPAC direct climate cooling petition for some possible options: https://drive.google.com/file/d/1yHe2Fe6fU11odfcH-4GwdYDNTCk7uB-J/view?usp=sharing ). Any thoughts or data on this that might be helpful in working up (or not) this proposal would be appreciated. For example, the last sentence in this excerpt from a quote in this Guardian piece ( https://www.theguardian.com/environment/2023/jun/19/marine-heatwave-uk-irish-coasts-threat-oysters-fish-high-temperatures) shared in recent ocean heat spike thread: https://www.theguardian.com/environment/2023/jun/19/marine-heatwave-uk-irish-coasts-threat-oysters-fish-high-temperature suggests that this may be a factor causing the recent unprededented spike in ocean heating: "Piers Forster, a professor of climate physics at the University of Leeds, said: “Both Met Office and NOAA analyses of sea-surface temperature show temperatures are at their highest ever level – and the average sea-surface temperature breached 21C for the first time in April. These high temperatures are mainly driven by unprecedented high rates of human-induced warming. Cleaning up sulphur from marine shipping fuels is probably adding to the greenhouse gas driven warming..."" Best, Ron -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAPhUB9B0%2BSovib9pcGn1_a4_3abjXs0DfWkec7VM%2BhFQJEuvBw%40mail.gmail.com.
