Each year, global average surface temperature is calculated. How do we measure the temperature of the entire planet? It takes thousands of thermometers, but the math is pretty simple. Here are the steps.

How to measure global average temperature in 5 easy steps. Step 1: Measure temperature above land and the ocean in THOUSANDS of places around the world. A cartoon globe holds a thermometer. Step 2: Subtract the temperature you measure at each location from the usual temperature on that day. The globe shows today's temp (32 degrees Fahrenheit), the usual temp (29.5 degrees Fahrenheit) and the difference between the two (2.5 degrees Fahrenheit). The globe says, "The difference is called the ANOMALY." Step 3: Repeat steps 1 and 2 for each day of the year. Step 4: Divide the planet into a grid of 2,592 squares. Calculate the average temperature anomaly for each square. The globe looks at its body, covered in a grid, and says, "I'm covered in SQUARS!" At the end of the years, you will have: 2, 592 locations in the grid, multiplied by 365 daily temperatures, to get 946,080 temperature anomalies. The globe says, "That's nearly a MILLION!" Step 5: Take the average of all temperature anomalies from all over the world. Compare this with other years. A graph shows the anomalies from 1980 through 2015. The anomalies show that it's warmer than usual. Cartoon by Lisa Gardiner at the UCAR Center for Science Education. These steps are based on NOAA's method of calculating global average surface temperature.