Why are 1/5 of world's reptiles facing extinction?

 A Good example of this is iguanas in Florida during the polar Vortex Freezes. What happens to iquanas when it freezes? 

Answer: What happens is their blood stops moving because they are cold blooded and don't have fur so that they have to have heat to survive. This is why more reptiles tend to live in warmer areas than in colder areas. For example, in southern California lizards are all over the place from small to large ones. But, when you travel north on the coast where I live nearer to San Francisco you don't see them much or at all. There are things like Salamanders but they seem to do okay in colder weather because they go under rocks where they might conserve body heat more?

So, climate change isn't just a big deal for reptiles it is a potential for extinction for reptiles because they don't do with a lot of change in their environments very well at all. This is why all the bigger reptiles like T Rex and others went extinct when the meteor hit earth 65 million years ago because they didn't have caves big enough to hide in to protect themselves from the cold which came from a several year nuclear winter.

However, some creatures adapted by moving into the oceans of the world and waters. Some of these survived. Will some reptiles migrate to the seas which might keep them alive this time too?

Possibly.

For example, Polar Bears are interbreeding with Grizzly bears which makes Grolar Bears or Pizzly bears (your choice).

Many many species are faced with finding ways to change or die right now here on earth.

Note: Iquanas also might be up palm trees or other trees because that is what they do. So, when their blood freezes they often fall out of these trees and fall on the ground. This is a very vulnerable position where the iquanas are incapacitated so dogs and other animals could easily eat them and they since they are comatose temporarily might be dead from other animals. This is just one of the problems that reptiles are facing as the climate changes. Just one freeze where iquanas live might kill a whole bunch of them from cars driving over them, people walking on them or kicking them, animals or birds eating them etc.

This is one path to potential extinction for any species worldwide.