Weather modicifation has been a dream military tool, with some unprecedented applications. They are as far away from saving the environment as you could get.
Climate change will harm coral at higher latitudes, at a slow enough rate they will migrate southwards, the rampant agricultural runoff will keep going regardless of the climate though and it has just as much a negative impact. Talking about fertilisers flowing into the reef and farmers causing much of the damage is a quick way into political suicide. It's not an easy issue to solve in a country with a 24 hour news cycle full of ever more outrage.