The Arctic Ocean, areas covered by sea ice, grows and shrinks over the course of each year. Every fall, as less sunlight reaches the Arctic and air temperatures begin to drop, additional sea ice forms. Then once spring arrives with more sunlight and higher temperatures, the ice begins to melt back, shrinking to its minimum extent each September. These areas covered by ice increase through the winter, usually reaching its maximum extent in early March. 

Through 2018, the downward trend for the summer minimum in September was 12.8 percent per decade relative to the 1981–2010 average. Since satellite-based measurements began in the late 1970s, data show a trend of more ice melting away during summers and less new ice forming during winters. Summer ice declines have been especially rapid since the start of the twenty-first century. And over the past 40 years.. the area covered by ice has shown a dramatic decrease. 

Climate scientists are particularly concerned about the decrease of sea ice because its white surface reflects up to 80 percent of incoming sunlight, deflecting additional energy away from the planet. With less ice present, the dark surface of ocean water absorbs more sunlight energy, leading to warming the atmosphere and melting more of the ice.

Scientists are still actively studying the effects of this positive feedback loop to help them understand and predict how the observed decrease in Arctic sea ice will affect the global climate system over these next coming decades. If the pattern keeps the way it is, the arctic will see ice-free summers by 2050 as the globe warms. Following that, ice ages over the last million years ended when the tilt angle of the Earth’s axis was approaching higher values. Could we see this again?