2A. Arctic sea ice naturally grows and shrinks throughout the year. However, Arctic sea ice is now declining over time due to warmer temperatures. One way that researchers measure changes in sea ice is through minimum extent, or the area in which at least 15% of the ocean is covered in ice. Figure 2 shows the average monthly Arctic sea ice extent for April from 1979 to 2022. Average Monthly Arctic Sea Ice Extent April 1979 - 2022 w - - w b &= Extent (millions of square kilometers) - = w N National Snow and ice Data Center 13! 1980 1984 1988 1992 1996 2000 2004 2008 2012 2016 2020 Year Figure 2. Average monthly April Arctic sea ice extent from 1979 to 2022 in millions of square kilometers. The average is shown in blue. Credit: National Snow and Ice Data Center