1.
the variety of life on earth
2.
the natural rate at which species go extinct
3.
a time when most species go extinct in a short time
4.
the destruction of habitat
5.
the use of natural resources faster than they are replenished
6.
the surge in human population in the 20th century
7.
long-term changes in temperature
8.
plants/animals in non-native environments which they harm
10.
age of humanity becoming a major force
