Arctic ice spread to its largest footprint of the year March 18. It was smaller than normal, but not as small as a year earlier.
The ice cap, defined as the total surface area of ocean that is at least 15 percent ice, reached 5.88 million square miles, according to the National Snow and Ice Data Center. A year ago, the ice cover was the smallest since 1979, at 5.65 million square miles. It has averaged 6.12 million square miles since 1979.
The peak was almost two weeks later than previous years, typically about March 6. Walt Meier, a research scientist at the center, isn't sure why that is but theorizes it's because the ice has more room to grow because of increased melting during the summer months. Last year's minimum ice cover, reached in September, nearly matched a record set in 2007, according to the center.