How we know past climates: ice cores, tree rings, sediments
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Ice, a tree ring, a sediment layer and a pollen grain in a row. A classmate says no one can know past climates because no one measured them. Which reply fits NOAA, by Esme's reading?
- No; satellites have watched for centuries
- Correct; thermometers are the one valid record
- No; ice cores, tree rings and sediments preserve climate signals
- No; thermometer records already reach back about 800,000 years in Antarctica
Read this first
Ring widths of a rain-sensitive tree (model data)
Year Ring width 1901 3 mm 1902 1 mm 1903 4 mm A student says a wide tree ring always means a warm year. Which reply fits NOAA, by Jun's reading?
- Correct; wide rings mean cold years
- No; ring width shows the tree's age
- No; it depends on whether warmth or moisture limits that tree
- Correct; ring width tracks heat for each kind of tree in a forest
Light oxygen moving from the sea into an ice sheet. A student says extra heavy oxygen in old sea shells means a warm time. Which reply fits NASA, by Kira's reading?
- No; heavy oxygen means heavy rain
- Correct; the ice sheets were melting
- Correct; warm water makes extra heavy oxygen build up in the shells
- No; light oxygen was locked in ice, so it was a cold, icy time
Model data: the top 50 m of an ice core hold 1,000 yearly layers; a deeper 50 m section holds 5,000. Why the difference, and what is the deep rate, by Luz's math?
- Compression; about 20 years per meter
- Compression; about 100 years per meter deep down
- Faster snowfall long ago; 100 years per meter
- Compression; about 250,000 years in each meter deep down
Model data: a lake gains about 1 mm of sediment a year. How many years does a 2.5 m core hold, by Milo's math?
Use the picture in question 4.
- About 250 years
- About 25,000 years
- About 2.5 years
- About 2,500 years
The EPICA core reaches about 800,000 years over about 3,189 m (NOAA). About how many years per meter is that on average, by Noah's math?
Use the picture in question 4.
- About 0.004 years per meter
- About 250 years per meter
- About 25 years per meter
- About 2,500 years per meter
Four evidence cards, labeled A to D. Which evidence best supports a cold period about 20,000 years ago, by Pia's reading?
- Thermometer readings from that time
- One wide tree ring
- Ice-core oxygen and sediment shells both point to more ice and colder air
- A single pollen grain
Several proxy records lined up on one timeline. NOAA: long records tend to show less short-term detail. Which record best shows year-to-year changes over the last 500 years, by Ren's reading?
- A tree-ring record with one ring a year
- The deepest section of an 800,000-year ice core
- A deep-sea core spanning millions of years
- A single pack rat midden
Use this
Table, Ice-core CO₂ and Antarctic temperature (NOAA NCEI), with columns About how long ago, CO₂ in trapped air (ppm), Temperature vs last 1,000 years: 20,000 years, 194, −9.4 °C; 128,000 years, 276, +3.4 °C; 140,000 years, 193, −9.1 °C. Note: CO₂: Antarctic composite (Bereiter et al. 2015); temperature: EPICA Dome C (Jouzel et al. 2007); values rounded.
Which pattern in the ice-core table best supports that CO₂ and temperature rose and fell together, by Tala's reading?
- Both cold rows hold about 193 to 194 ppm; the warm row holds about 276 ppm
- CO₂ stayed at about 276 ppm in each row while the temperature swung
- The coldest rows hold the most CO₂, about 276 ppm each
- Thermometers frozen deep in the ice measured both the CO₂ and the warmth directly
Ice, a tree ring, a sediment layer and a pollen grain in a row. Which summary of proxies fits NOAA, by Bo's reading?
- Forecast models of the future
- Natural recorders, like ice, trees, sediments and pollen, extend records past instruments
- One proxy by itself gives the full picture
- Thermometers from the distant past