Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.

Fact 1: nerves can be used to feel heat and pressure on the skin. 
Fact 2: There are two types of nerves in the body that can "feel" pain.
Heat and pressure on skin can cause feelings of pain.

Fact 1: dehydrating food is used for preserving food. 
Fact 2: Dehydration is the removal of water.
Removing water preserves food.

Fact 1: global warming is when worldwide temperature increases. 
Fact 2: Mass extinction occurs in the ice age and global warming periods.

When worldwide temperature increases, mass exctinction occurs.