What covered large parts of Earth's surface during ice ages?
Glaciers which are large sheets of ice
What are possible explanations for major climate changes?
Movement of the continents, variations in the position of Earth relative to the sun, major volcanic eruptions, and changes in the sun's energy output
How can volcanic activity change climates?
Aerosols become suspended in the upper atmosphere and block out incoming solar radiation which lowers temperatures.
What principle do scientists follow in studying ancient climates?
If plants or animals today need certain conditions to live, then similar plants and animals in the past also required those conditions
How do movements of the continents affect climate?
A location that moves toward the equator gets warmer, and one that moves away gets colder. Movement of continents changes wind and ocean currents as well.
What is a sunspot?
A dark, cooler region on the surface of the sun
How do scientists use pollen to study ancient climates?
They look at pollen that has accumulated at the bottom of lakes to find out what kinds of plants lived in an area
What are aerosols?
Solid particles or liquid drops in gas
What are three pieces of evidence scientists look at to study ancient climates?
Pollen, tree rings, ice cores, fossils
What do scientists think causes ice ages?
When Earth's orbit becomes more elliptical (oval shaped), it gets less direct light which causes an ice age.
How do scientists use ice cores to study ancient climates?
By drilling into ice, scientists can look at the layers of ice. The ice may contain things like pollen and dust.
How can solar energy affect climate?
When the sun gives off less solar energy, Earth's climates cool
How do scientists use tree rings to study ancient climates?
Trees add a new ring each year. Thicker rings indicate a good growing season that was long or wet. Narrow rings indicate a dry year or short growing season.