Name three common sources of data scientists use to study past climates.

• A. The fossil record, signs of past glaciers, and ice cores
• B. Current weather data from cities
• C. Satellite data only
• D. Laboratory experiments with synthetic atmospheres

Answer: (A)

Paleoclimate data come from natural records that preserve signals about past temperatures, precipitation, and atmospheric composition. The three sources mentioned are classic proxies scientists use to reconstruct climate before modern instruments. Ice cores are especially powerful because they trap air from different ages; analyzing the trapped gases and isotopic ratios within them reveals past temperatures and greenhouse gas levels over long timescales. The fossil record provides indirect clues through how species distribution, community structure, and ecological traits shifted in response to climate change, helping us infer the environmental conditions of those times. Signs of past glaciers, like moraines and glacial sediments, show where ice extended and how long it remained, offering direct evidence of colder intervals and the timing of glacial cycles.

These proxies are highly valued because they extend climate information far beyond the modern era and can be dated with reasonable precision, and they often corroborate each other to give a coherent picture of Earth's climate history. Other options mostly describe contemporary data or experimental simulations that do not by themselves document long-term past climates in the same way these natural records do.