The corals are casualties of surging global temperatures which have smashed historical records in the past year — caused mainly by fossil fuels driving up carbon emissions and accelerated by the El Niño weather pattern, which heats ocean temperatures in this part of the world.
The difficulty is likely deciding which genes to turn on and which ones to turn off.
What scientists are doing instead is taking corals that are demonstrating heat-resistance, propagating them in labs, and trying to introduce them back into the wild; it’s a kind of directed evolution. The difficulty is lack of funding and keeping up with climate change.