1. Commas

2. Separating Independent Clauses
What is an independent clause?
It is a group of words with a subject and predicate that makes sense by itself.
Examples:
Polar bears are at risk due to melting glaciers and sea ice.
Scientists labeled recent temperature increases as abnormal.
Subordinating conjunctions
Difference from a dependent clause:
When temperatures in the Arctic increase
Because sea ice melts sooner than before

3. What is a compound sentence?
It is made of two closely related independent clauses.
The two clauses can be joined by a comma and a coordinating conjunction (and, but, or).
They can also be joined by a semicolon (;).
Examples:
Not all dry regions are deserts, but all dry regions are fragile ecosystems.
Areas with fewer plants cannot sustain existing animal populations; these populations disappear.