When CO₂ levels were low, temperatures were ______ and Earth was _____________.

• cooler; in an ice age (glacial period)

• cooler; warming (interglacial period)

• warmer; in an ice age (glacial period)

• warmer; warming (interglacial period)

When CO₂ levels were high, temperatures were ______ and Earth was _____________.

• cooler; in an ice age (glacial period)

• cooler; warming (interglacial period)

• warmer; in an ice age (glacial period)

• warmer; warming (interglacial period)

Oxygen isotopes are used to measure past temperatures. Isotopes have different numbers of...

• protons

• neutrons

• electrons

A greater amount of ¹⁸O in an ice core sample means temperatures were _________ because there was ________ evaporation.

• colder; less

• colder; more

• warmer; less

• warmer; more

A greater amount of ¹⁸O in a foram ocean sediment sample means temperatures were _________ because there was ________ evaporation.

• colder; less

• colder; more

• warmer; less

• warmer; more

How does the rate of modern warming compare to other periods?

• It is slower than the rate in the Cretaceous and PETM periods.

• It is equal to the rate in the Cretaceous and PETM periods.

• It is faster than the rate in the Cretaceous and PETM periods.

What is the primary cause of modern warming?

• peat fires

• respiration

• fossil fuel burning

• volcanic eruptions

How does a slow rate of warming impact the biosphere?

• Nearly all creatures go extinct.

• Nearly all creatures have time to adapt or migrate.

Choose which of the following have occurred due to modern warming. (choose all that are correct)

• Ocean acidifcation

• Glaciers melting

• Poleward migration of many species

• Coral bleaching

• Extinctions

Which period has the fastest rate of warming in regards to changing climate?

• Cretaceous Period

• PETM Period

• Modern Warming