Yes, but we're rapidly approaching a point where the planet's own greenhouse gases take us several degrees further even if we stop emissions entirely. A sunshade could head that off, and give us time to pull CO2 back out of the atmosphere.
* that good black chernozem soul which makes up the Russian breadbasket would turn into desert in south of this region, while in the north the soil is too poor
* mass forest fires would choke the air
* melting permafrost would destroy existing badly maintained infrastructure and cities
If Russia is hoping for positives out of climate change they are in for a surprise
Risks 1) Social destabilization driven by collapse of southern agricultural communities and their migration northward. Keep in mind that already the northern communities are being heavily impacted by the thaw of the permafrost that many cities and towns are built on - to establish more infrastructure means building on a growing swamp. To be able to get crops to market, it means building very long roads on a growing swamp as well - remember that Russia suffers from a lack of internal rivers to convey agricultural products throughout it's vast geography.
2) Consequences of disturbances to fish stocks for northern communities - who are dependent on either fish directly, or seals and other species indirectly
3) Limited societal benefit of new hydrocarbon resources given the existing klepto-oligarchy - it's unlikely that new resources will be used to stabilise the broader community or social fabric.
4) Possibility that they cannot exploit said hydrocarbons due to global moratoriums or increased uptake in alternative energy sources
5) Broader geopolitical implications of social collapse of soviet satellites; some of which are currently heavily dependent on current rainfall patterns for cotton, wheat and other grains - Kazakhstan, Turkmenistan, etc - if these countries go to the wall - what does that mean for the Russian state? It's likely that Russia would have to invest aggressively in shoring up the southern borders. 6) China; the eastern regions of Russia could be a tempting acquisition for China looking for new agricultural land or control of northern ports such as vladivostok as ice coverage decreases- further exacerbating pressures on the central Russian government.
On the other hand a fractured/weak Europe means higher gas prices, no medling in russian affairs, less pressure by russian citizens drooling over the fence with their eyes fixed on european stability and wellfare, free hand to do as Russia pleases in ex Soviet states and so on.
The plan also requires a certain amount of stationkeeping, probably with solar sails, and if you can do that then you can also move the elements out of the way of the sun entirely, with a little time.
2) It sort of misses the point- that might address the known-unknowns of the primary effect (solar radiation hitting Earth). It does nothing to address unknown-unknowns or even secondary or tertiary effects.
The mere presence of the shields might block solar wind, distort Earth's magnetic field, reflect / refocus cosmic radiation, amplify affect of solar flares, interfere with radio or satellite communication...
We just don't know. And the stakes are too big, even compared to worst case global warming.
The bigger the potential impact a project has, the better prepared you should be to undo or mitigate it, before it causes problems worse than the ones it's meant to fix. I don't see that here.
All the "mights" you mention can be easily evaluated by straightforward physics.
You can't possibly think that it's straightforward to model all those physical aspects for 16 trillion objects. We don't even have the 3-body solution solved; just predicting the gravitational behavior is unbelievably complex and chaotic. That many degrees of freedom is simply unsolvable (without quantum computing).
It's hubris to believe we can predict even basic behavior and interference of such a project, let alone intended or unintended side effects, whether known or unknown.
1. the alternate proposals won't work (at all, which seems unlikely)
2. the expected case for climate change isn't actually as bad as people are saying it is
or
3. people don't actually care about climate change as much as they care about using climate change to push their own agendas
Personally, I lean towards #3. But that still doesn't make me very happy with climate activists.