Last Friday, on the same island, 36 Nobel Prize winners took up another cause: climate change, which they said poses a “threat of comparable magnitude” to nuclear war.

“If left unchecked, our ever-increasing demand for food, water, and energy will eventually overwhelm the Earth’s ability to satisfy humanity’s needs, and will lead to wholesale human tragedy,” the Nobel laureates’ declaration reads. “Already, scientists who study Earth’s climate are observing the impact of human activity.”

The declaration marked the culmination of the 65th Lindau Nobel Laureate Meeting, a week-long gathering of 65 Nobel laureates held on Mainau Island, a small island in Lake Constance that borders Germany, Austria, and Switzerland.

“Based on the IPCC assessment, the world must make rapid progress towards lowering current and future greenhouse gas emissions to minimize the substantial risks of climate change,” the declaration continues, highlighting the 2015 United Nation Climate Change Conference in Paris as a chance to take steps toward international climate action.

“This endeavor will require the cooperation of all nations, whether developed or developing, and must be sustained into the future in accord with updated scientific assessment,” the declaration concludes.

Thirty-five of the declaration’s signatories have been awarded a Nobel Prize in a scientific field, ranging from medicine to chemistry. The 36th signatory was Kailash Satyarthi, who was awarded the 2014 Nobel Peace Prize for his work in children’s rights.

“I see this issue as the single greatest threat to human prosperity, and I believe it is important for the best scientific evidence to be used by policy [makers] in making their decisions,” Brian Schmidt, who was awarded the 2011 Nobel Prize for physics, said in a press statement.

That sentiment was echoed by George Smoot, recipient of the 2006 Nobel Prize for physics, who said that “the evidence is very strong that the major portion of climate change is man made and that continuing business as usual presents great and increasing risk to humankind.”

But not every Nobel laureate present at the conference signed the declaration — or shared the signatories’ concerns about climate change. Earlier in the week, Nobel Prize-winning physicist and climate denier Ivar Giaever gave a lecture questioning the science and policies behind climate change, which in the past he has likened to a “new religion.” According to E&E News, Giaever — who at the 62nd Lindau Nobel Laureate Meeting said that climate change was “absolutely” pseudoscience — explicitly criticized President Obama’s response to climate change, calling him a “clever person” that “gets bad advice.”

“I say this to Obama: Excuse me, Mr. President, but you’re wrong,” Giaever said. “Dead wrong.”