Salter S. 2021 Note for COP 26 on Marine Cloud Brightening

Present policies of most Governments, with a few predictable exceptions, concentrate on the desperate need to get to zero carbon emissions as soon as possible. This is a necessary but not sufficient objective. There is strong evidence from the Keeling curve below, about the difficulty. But if we could reduce carbon emissions to zero the concentration of atmospheric greenhouse gases will be what we have now plus what we will be emitting between now and the zero-emission date minus the amount taken up by the oceans. This means that typhoons, floods, droughts, bushfires, sea-level rise, Arctic ice loss and damage to coral will all be worse, perhaps much worse than now. If you think that present conditions are not acceptable you have to conclude that zero is not low enough. As well as reducing emissions we will HAVE TO remove greenhouse gases, probably with help from phytoplankton, and also do direct cooling a soon as we can and hopefully ramp it down as emissions reduce.