In hot water

This exercise is a part of Educator Guide: Earth’s Oceans Broke Heat Records in 2020 / View Guide

Directions for teachers: Ask your students to read the online Science News articleEarth’s oceans are storing record-breaking amounts of heat,” which explores how the upper oceans’ heat storage capacity has changed over time, and answer the following questions. A version of the story, “Earth’s oceans broke heat records in 2020,” appears in the February 13, 2021 issue of Science News.

1. What is the main finding described in the Science News article?

In 2020, the total amount of heat stored in the oceans’ upper 2,000 meters was higher than any other year on record dating back to the 1950s.

2. Why is tracking ocean temperature important?

Warmer waters melt more ice off Greenland and Antarctica, which raises sea levels. Warmer waters can also make tropical storms more intense.

3. Where did the ocean temperature data that the researchers used come from?

Ocean temperature data came from moored sensors, Argo floats, underwater robots and other instruments around the world.

4. How much heat energy did the upper oceans store in 2020 compared with the annual average from 1981 to 2010?

Upper ocean waters contained 234 sextillion joules more heat energy.

5. How does that amount compare with data from 2019? Why did the researchers come up with two estimates?

Upper ocean waters stored at least 1 sextillion joules and may have stored as much as about 20 sextillion joules more heat energy than 2019. Researchers thought their estimate of 20 sextillion joules may have been too high, so they used a different, more conservative mathematical model to come up with a second estimate.

6. About how many kettles of water could be boiled by the jump in heat energy storage from 2019 to 2020, according to the researchers? Why is there a range given in the article?

The increase in heat energy storage between 2019 and 2020 could boil and estimated 65 million to 1.3 billion kettles of water. A range is given because researchers came up with two estimates for the jump in heat energy storage.

7. Why do you think climate scientist Michael Mann compares the ocean heat records to the film Groundhog Day? You can look up the film if you are not familiar with it.

In the film, the same day repeats over and over again. Scientists are seeing a similar trend in ocean heat records over the last few years — each new year becomes the hottest ever recorded.

Dive into data
Answer the following questions after examining the graph below. The graph appears in a version of the story, “Earth’s oceans broke heat records in 2020,” in the February 13, 2021 issue of Science News.

a graph showing how much heat Earth's oceans stored from 1959 to 2020
T. Tibbitts

1. What does the graph show? Define the x- and y-axes and their units.

The graph shows the change in the annual average upper ocean heat content from 1958–2020. The x-axis shows time in years, and the y-axis shows the change in ocean heat content from the baseline average in sextillion joules.

2. Around what year did the oceans begin to store more heat than the baseline average? How much more heat did the oceans store that year?

The oceans began to store more heat than the baseline average around 1998. That year, the oceans stored about 25 sextillion joules more heat energy than the baseline average.

3. State the general trend of the data shown in the graph, including the general trend in the rate of change in heat content.

The upper oceans’ average annual ocean heat content has generally increased since 1958. The rate appears to increase gradually from 1958 to about 1985. After that, the rate appears to increase more drastically and rapidly.