An enormous floating ice shelf in Antarctica that has existed since the last Ice Age 12,000 years ago collapsed this month with staggering speed during one of the warmest summers on record there, scientists say.

Scientists stopped short of blaming the collapse on global warming caused by human activity. But they noted that the ice shelf had persisted through previous climate changes well before civilization began altering the environment.

Satellite images show that the piece of the Larsen Ice Shelf collapsed during a five-week period that ended March 7. It splintered into a plume of drifting icebergs.

The collapsed area was designated Larsen B, and it was 650 feet thick and with a surface area of 1,250 square miles, or about the size of Rhode Island.

Larsen B is separate from a new, giant iceberg that satellites are tracking off Antarctica.

The iceberg  designated B-22  broke free from the Thwaites Ice Tongue, a peninsula of ice and snow extending into the Amundsen Sea on the other side of the Antarctic Peninsula. B-22 is about 53 miles long and 40 miles wide, according to the National Ice Center operated by the Navy.

In contrast, the Larsen ice shelf is on the Antarctic Peninsula and extends about 1,000 miles closer to the tip of South America than the rest of the Antarctic continent.

In recent months, with the polar summer just beginning, temperatures were already creeping above freezing in the peninsula region. Scientists said there has also been a 50-year warming trend in the peninsula, which is considered a sensitive, early indicator of global climate change.

“We’re seeing a very rapid and profound response by the ice sheet to a warming that’s been around for just a few decades,” said Ted Scambos of the National Snow and Ice Data Center at the University of Colorado.

“We can use this as sort of a guide for what’s going to happen if the rest of the Antarctic should begin to warm because of climate change,” he said.