How we know past climates: ice cores, tree rings, sediments
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
Read this first
Use this
Ice, a tree ring, a sediment layer and a pollen grain in a row.
Why do scientists need proxy data, by Bo's reading (NOAA)?
- Thermometers have recorded millions of years
- Weather does not change over time
- Instrument records reach back only to about the 1800s
- Satellites have watched for 1,000 years
Which of these is a proxy record of past climate, by Kira's reading (NOAA)?
- Tomorrow's forecast
- Today's rain-gauge reading
- Tree rings
- A modern weather-satellite photo
Why do ice cores show yearly layers, by Jun's reading (NOAA)?
- Layers form from ocean waves
- Each layer is one century of snow
- Each storm makes one yearly layer
- Summer and winter snow differ in texture and chemistry
What do the air bubbles in ice cores hold, by Luz's reading (NOAA)?
Use the picture in question 3.
- Ocean water
- Samples of the past atmosphere's gases
- Modern air pumped in by the drill during coring
- Tree pollen and nothing else
Ring widths of a rain-sensitive tree (model data)
Year Ring width 1901 3 mm 1902 1 mm 1903 4 mm In temperate regions, how many rings does a tree usually add each year, by Noah's reading (NOAA)?
- One per decade
- Two, one each season
- Ten
- One
A tree depends on rain in its growing season. What does a wide ring show, by Pia's reading (NOAA)?
- A dry year
- A year when the tree did not grow
- A wet year
- A cold, snowy winter
What is cross dating, by Ren's reading (NOAA)?
- Counting the rings on a single stump by itself
- Measuring the height of a tree
- Matching tree rings to ice layers by color
- Matching ring patterns in old wood to living trees to fix exact years
Use this
Light oxygen moving from the sea into an ice sheet.
Oxygen comes in light (oxygen-16) and heavy (oxygen-18) forms. Which evaporates slightly more easily, by Tala's reading (NASA)?
- Neither one evaporates
- Light oxygen-16
- They evaporate equally
- Heavy oxygen-18
During ice ages, why is the ocean richer in heavy oxygen, by Zee's reading (NASA)?
- Light oxygen gets locked away in the growing ice sheets
- Plankton eat the light oxygen
- The cold ocean makes heavy oxygen
- Heavy oxygen is locked away in the growing ice sheets there
In a polar ice core, one layer holds less heavy oxygen (oxygen-18) than the layers around it. What does that suggest, by Esme's reading (NASA)?
- A volcanic eruption
- A wet tree-ring year
- Colder conditions when the snow fell
- Warmer conditions when the snow fell