You do realise that the ecological disaster brought upon by climate change means near 0 biodiversity? This means we lose 2 thirds of our medicines since they're created from endangered natural resources, so cancer, obesity and general illness related deaths will sky rocket.

Between that, more favourable conditions for disease (warmer and wetter) coupled with lowered genetic diversity means that our crops are in serious danger of falling to a blight. See the Irish Potato Famine, that killed a million people. Of course, we could always rely on a more diverse range of crops, but that would require them to be alive in the wild in the first place to cultivate. Something unlikely following climate change.

That's the least of it as well, but are in my opinion the two largest issues. Between a very large risk for worldwide mass starvation (without overexaggeration there - this would be worldwide. We live in a globalised society) and creating a disease field day, I have no doubt it would kill substantial amounts of people.