The debate over whether global warming is natural or manmade is an artificial one: scientists know that both factors can affect the planet’s temperature.

The real question is which factor is doing the heavy lifting — and a new report in Nature released Wednesday says that on the Antarctic Peninsula, at least, human-generated greenhouse gases have almost certainly been by far the most important driver of warming over the past half-century.

Scientists are intrigued with this corner of the world because it’s warming faster than anyplace else on Earth.

The planet as a whole has heated up by about 1.3°F since 1900, but on the peninsula, it has shot up by a whopping 5° in just 50 years, forcing massive ice shelves to disintegrate and penguin colonies to collapse.

Heat trapping greenhouse-gas emissions are the obvious culprit, since they’ve increased dramatically over that same 50 years, but scientists prefer hard evidence to presumption, so a team from the British Antarctic Survey has been drilling into ancient ice to see how the current warming stacks up against what happened in the ancient past.

If the kind of warming happening now also happened before we started burning fossil fuels, it would cast doubt on the human contribution.

What the scientists discovered, however, removed any doubt.

“We found that the peninsula has been warming for the past 600 years,” said lead author Robert Mulvaney, of the British Antarctic Survey, in an interview.

“But the rate of warming has been much faster during the past century, and fastest over the past 50 years.”