The sea ice in the Arctic Ocean has melted to its smallest ever level in the latest dramatic sign of the long-term impact of global warming, US researchers said Monday.

Scientists at the University of Colorado at Boulder said that data recorded Sunday broke the 2007 record for the lowest extent of sea ice and that the melt could become even more significant with several weeks of summer left to go.

The National Snow and Ice Data Center at the university said in a statement that the decline in summer Arctic sea ice "is considered a strong signal of long-term climate warming."

The sea ice fell to 4.10 million square kilometers (1.58 million square miles), some 70,000 square kilometers (27,000 square miles) less than the earlier record charted on September 18, 2007, the center said.

Mark Serreze, director of the center, said that the record was all the more striking as 2007 had near perfect patterns for melting ice, but that the weather this year was unremarkable other than a storm in early August.

"The ice is so thin and weak now, it doesn't matter how the winds blow," Serreze said in the statement.

Walt Meier, a scientist at the center, said that the record was on one level "just a number, and occasionally records are going to get set."

"But in the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing," he said.

The planet has charted a slew of record temperatures in recent years, with 13 of the warmest years ever taking place in the past decade and a half.

Scientists say that climate change is largely caused by human emissions of carbon and other greenhouse gases, which hinder the planet's reflection of the sun's heat back into space.

The melting of Arctic has helped open up new shipping lanes but is also believed to hold serious consequences for the rest of the planet as the ice serves a vital function in keeping the planet cool.