[Physicist]

Nobody would contend that during the last ice age that temperature at 32° S didn't drop at least 2°.

Nobody has to. If you are contending that it dropped MORE than 2°, YOU have to demonstrate it. You're the one making the bold claim, here.

I warn you, it's not an obvious point. Ocean temperatures in specific locations can be dominated by the warm and cold ocean currents, rather than local weather conditions.

But let's assume that you have managed to show that the reefs died out in the last ice age. Maybe you've done the simple thing, and performed some carbon dating on the reefs themselves to show that they were quiescent during the last ice age, instead of doing complex numerical modelling of the ocean currents during that time period. Now you also have to show that the reefs could not have been recolonized from elsewhere, afterwards.

Can do?

[Truth666]

"If you are contending that it dropped MORE than 2°, YOU have to demonstrate it. You're the one making the bold claim, here."
It's not me who is making this claim, it is the official school material that I'm using as reference to prove that it's incompatible with evolution theory. That material teaches us that 10,000 years ago temperatures were at least 5°C cooler than today. It doesn't tell some areas were less than 2° C colder than today.