What is significant about the Paleocene-Eocene Thermal Maximum (PETM)?:
a. There is nothing significant about the PETM.
b. The rate of change at the PETM is significantly lower than the current temperature rate of change, indicating that we have reached a point of no return.
c. The rate of change at the PETM is significantly higher than the current temperature rate of change, indicating that we have not reached a point of no return.
d. The rate of change at the PETM is similar to the current temperature rate of change, allowing us to look to the PETM for an indication of what may happen to us.