Monday
Monday: Taking Earth's Temperature
Rocket arrives at Station Rooftop waving a single thermometer. "One reading," he says. "Sixty-one degrees. That is Earth's temperature today."
Raven laughs kindly. "That is Station Rooftop's temperature. What do you notice when you look at a world map?"
Rocket squints at the map pinned to the wall. "Deserts. Ice. Oceans. Mountains."
"So how could anyone take the temperature of a whole planet?" Raven asks.
Nova hovers over the map and sprinkles thousands of tiny lights across it. "What if every one of these is a thermometer?" she asks.
"And ships, and buoys," Raven adds, "all reporting at once."
Rocket lowers his thermometer. "Then somebody has to average all of that. Every single day."
Thousands of thermometers
NASA's record of global temperature uses readings from more than 25,000 weather stations around the world.
It also uses instruments on ships and buoys that measure the sea surface, plus research stations in Antarctica.
NOAA builds its own record the same way. Both records reach back into the 1800s: NASA's to 1880 and NOAA's to 1850.
Several independent research groups around the world do this analysis separately. NOAA notes that they all show a similar upward trend.
The goal is to track change, not to list every day's reading. So scientists convert each reading into an anomaly.
An anomaly is the difference between a reading and the long-term average for that place and date.
A reading of 61 degrees means little on its own. A reading 3 degrees above normal for that spot means something.
NASA compares each year to the 1951 to 1980 average. NOAA compares to the average for the whole 20th century, 57.0 degrees Fahrenheit.
- Read the question.
- Tap your answer.
What the record says
NOAA reports that 2024 was the warmest year since global records began in 1850.
NASA agrees. In NASA's record, which begins in 1880, the hottest year on record remains 2024.
NASA found 2025 was 2.14 degrees Fahrenheit above its 1951 to 1980 average, close behind 2024.
NOAA notes the ten warmest years in its record all happened in the past decade, 2015 to 2024.
NASA puts it simply: the ten most recent years are the warmest on record.
| Statement | True or false? |
|---|---|
| One thermometer in one place can measure Earth's temperature. | ? |
| NASA's record begins in 1880 and NOAA's in 1850. | ? |
| Both NASA and NOAA found 2024 was the warmest year on record. | ? |
| The ten warmest years in NOAA's record are spread evenly across 175 years. | ? |
| Independent groups analyzing the data all show a similar upward trend. | ? |
Earth's energy balance
NOAA explains that the global average surface temperature shows the state of Earth's energy balance.
That balance is the sunlight Earth absorbs minus the heat it radiates back to space.
When the two amounts match, the average temperature stays steady. When they are out of balance, Earth warms or cools.
NOAA states that the average temperature has been rising because human-produced greenhouse gases make Earth absorb more energy than it radiates.
Tomorrow you learn exactly how those gases trap heat.
Average them. Is your average the same as any one reading? That is the problem scientists solve at planet scale.
Never look at the Sun while finding a sunny spot.
Every number in the lessons comes from those pages. The lessons make no predictions and place no blame on any family.
Good thinking. Tomorrow: the greenhouse effect, and what has been adding to it.