obviously I wouldn't say/think there are no risks with geoengineering but it said: "the use of geoengineering to reduce the amount of solar energy that reaches the atmosphere is too risky. " without qualifying that with how they arrived at such a conclusion nor saying how much reduction do they mean by the word "reduce" there.
But, what concerns me much more, I fear they may have missed the point because, yes there are bound to be risks, but what if the risks of NOT doing it are even greater!? Have they compared the risks of doing it with the risks of not doing it to make a rational assessment on whether we should take the risk of doing it despite those risks? Did they even consider this question?
It makes a point where it says:
"The longer we wait, the more likely it will become that we will need to deploy some forms of carbon-dioxide removal to avoid the worst impacts of climate change,"
because we are surely a long way off from deploying "carbon-dioxide removal" on that sort of scale and, in the mean time, what if the effects of global warming becomes just too serious? So I think we should seriously consider planning for a last-resort measure of deploying a measure to make whatever necessary reduction in the warming from solar radiation absorption and then only deploy such a plan if or when all other measures we deploy prove to be not good enough; -A kind of last-resort plan B, if you like, ready and waiting just-in-case. I think that, at the very least, we should risk deploying it if and when we eventually come to know for certain that all the ice caps will melt if we did NOT deploy it!!! SURELY, in that event, you couldn't keep saying "the use of geoengineering to reduce the amount of solar energy that reaches the atmosphere is too risky" !!! Well, that is just my way of thinking anyway.