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STANDARDS
NGSS: ESS3.D
CCSS: Writing: 1
TEKS: 6.3D, 7.3D, 8.3D, 8.5D, C.3F, C.13D, C.14B
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Historic Climate Discovery
Eunice Foote pinpointed a major cause of climate change—more than 160 years ago
AS YOU READ, THINK ABOUT how greenhouse gases trap heat in the atmosphere.
PICTORIAL PRESS LTD/ALAMY STOCK PHOTO
“THE HIGHEST EFFECT OF THE SUN’S RAYS I HAVE FOUND TO BE IN CARBONIC ACID [CARBON DIOXIDE] GAS.” —EUNICE FOOTE
The year is 1856. Eunice Foote, a physicist from Seneca Falls, New York, is about to conduct an experiment. She wants to measure the warming effect of sunlight on gases in Earth’s atmosphere.
Foote places glass cylinders filled with different gases in the sun and measures the temperature of each over time. She finds that certain gases absorb more heat than others and that carbon dioxide (CO2) gas traps the most heat—by far. From this, Foote comes to a groundbreaking conclusion. She proposes that a greater amount of carbon dioxide in the atmosphere would cause temperatures on Earth to rise.
The year is 1856. Eunice Foote is about to conduct an experiment. She’s a physicist from Seneca Falls, New York. Sunlight warms the gases in Earth’s atmosphere. Foote wants to measure this effect.
Foote fills glass cylinders with different gases. Then she places them in the sun. Over time, she measures the temperature of each. She finds that certain gases absorb more heat than others. One gas traps the most heat by far. It’s carbon dioxide (CO2). Foote’s findings lead her to a groundbreaking conclusion. She proposes that more carbon dioxide in the atmosphere would cause Earth’s temperatures to rise.
Since Foote’s experiment, the concentration of carbon dioxide in the atmosphere has risen by 129 parts per million and the average global temperature has increased by 1 degree C (1. 8 degrees F).
Today, scientists know that carbon dioxide is a powerful contributor to the greenhouse effect. Human activities like burning fossil fuels—coal, oil, and natural gas—have increased the amount of carbon dioxide and other heat-trapping greenhouse gases in the atmosphere. Because of this, the average temperature of Earth’s atmosphere is steadily increasing—just as Foote had predicted. This is causing ice caps to melt, sea levels to rise, and extreme weather to intensify.
Foote was the first scientist to connect carbon dioxide levels to climate change. Unfortunately, she didn’t get credit for her discovery until 2011, when a retired scientist stumbled across her research. Let’s take a closer look at Foote’s simple yet ingenious experiment.
Today, scientists know that carbon dioxide plays a powerful role in the greenhouse effect. Humans burn fossil fuels—coal, oil, and natural gas. This and other human activities have increased the amount of carbon dioxide and other heat-trapping greenhouse gases in the atmosphere. Because of this, the average temperature of Earth’s atmosphere is increasing steadily. That’s just what Foote predicted. This is causing ice caps to melt and sea levels to rise. It’s also making extreme weather worse.
Foote was the first scientist to connect carbon dioxide levels to climate change. Sadly, she didn’t get credit for her discovery until 2011. That’s when a retired scientist found her research. Let’s take a closer look at Foote’s experiment. It’s simple but clever.
EYEWASH
THE SETUP
Foote placed thermometers inside two glass cylinders, filled each one with a different gas, and left them side by side in the sun. Every few minutes, Foote recorded changes in temperature. She then moved both cylinders into the shade, let them come to the same temperature, and recorded their\ temperatures over the same amount of time.
THE VARIABLES
Foote repeated her experiment three times. In the first trial, she tested air of different densities (mass in a given volume). In the second trial, she compared dry air with humid air. In the third trial, Foote filled one cylinder with carbon dioxide and the other with a sample of “common air” from the environment around her.
THE TRAPPING OF HEAT
The atoms—the smallest units of matter—that make up air molecules are constantly vibrating. For smaller gas molecules like oxygen (O2) and nitrogen (N2), which make up most of Earth’s atmosphere, these vibrations are limited. But gas molecules with three or more atoms—like greenhouse gases—vibrate in a way that absorbs radiation, which traps heat.
THE RESULTS
After both gases sat in the sun for the same amount of time, carbon dioxide was 20 degrees warmer than common air.
Experiment Data:
Trial 3: In the Sun
Measurement 1Common Air: 90 degrees FCarbon Dioxide: 90 degrees F
Measurement 2Common Air: 94 degrees FCarbon Dioxide: 100 degrees F
Measurement 3Common Air: 99 degrees FCarbon Dioxide: 110 degrees F
Measurement 4Common Air: 100 degrees FCarbon Dioxide: 120 degrees F
Here’s how greenhouse gases—like carbon dioxide, water vapor, and methane (CH4)—are causing Earth to heat up.
KATE FRANCIS
Energy from the sun reaches Earth, providing light and heat.
Clouds and Earth’s surface reflect about 30 percent of that energy back into space.
People burn fossil fuels to power cars, homes, and businesses. That releases greenhouse gases into the atmosphere.
Greenhouse gases trap reflected heat in the atmosphere, causing temperatures on Earth to rise. The more greenhouse gases produced, the hotter the planet gets.
Film a short video that introduces viewers to Eunice Foote and explains why she should be more well-known.