Back to topics

What can tree rings reveal about past climate?

A tree keeps a record of growth in its wood, but reading that record as climate history takes more than counting rings. Moisture, temperature, and other growing conditions can leave overlapping clues.

4–5 min

Questions you could explore

  • How can ring width, wood density, or other tree measurements preserve clues about growing conditions?
  • How does comparing and cross-dating several trees help distinguish a climate signal from the history of one tree?

Start reading

Ready to try your ideas aloud?

Your topic carries over. Record up to 2½ minutes, depending on your plan.

Environment and climate

Why can a city be warmer than nearby countryside?

The trip from a leafy edge of town to a dense street can also be a trip between different temperatures. Buildings, pavement, vegetation, and waste heat all affect the balance, and the contrast changes with weather and time of day.

3–5 min

Why can a city be warmer than nearby countryside?

Environment and climate3–5 minThe trip from a leafy edge of town to a dense street can also be a trip between different temperatures. Buildings, pavement, vegetation, and waste heat all affect the balance, and the contrast changes with weather and time of day.

Environment and climate

A trip through a wastewater treatment plant

Water disappearing down a drain begins another journey before it returns to a river or the sea. Inside a wastewater treatment plant, screens, settling tanks, and microbes tackle different kinds of pollution. Conventional sewage treatment produces effluent for controlled discharge; making recycled water suitable for drinking requires additional treatment and safeguards.

4–5 min

A trip through a wastewater treatment plant

Environment and climate4–5 minWater disappearing down a drain begins another journey before it returns to a river or the sea. Inside a wastewater treatment plant, screens, settling tanks, and microbes tackle different kinds of pollution. Conventional sewage treatment produces effluent for controlled discharge; making recycled water suitable for drinking requires additional treatment and safeguards.

Environment and climate

Where does the water go in a rain garden?

Rain runs quickly off a roof or pavement, but a planted hollow can give it somewhere to pause. A rain garden's ability to hold water and let it enter the soil depends on its surroundings and ground conditions.

3–5 min

Where does the water go in a rain garden?

Environment and climate3–5 minRain runs quickly off a roof or pavement, but a planted hollow can give it somewhere to pause. A rain garden's ability to hold water and let it enter the soil depends on its surroundings and ground conditions.

What can tree rings reveal about past climate? | Speech Topic | speaking.app