Both are human-caused, both are frightening, and A.I. has raced to the forefront of the global conversation. A.I. is “eating up all our attention,” a professor of environmental politics said recently, as warnings that humans are flirting with out-of-control artificial intelligence led to suggestions that A.I. has surpassed climate change as one of humanity’s gravest risks. Though the danger of the technology is hard to assess, the worst-case scenario — human extinction — makes other earthly concerns seem small.

“In terms of things that could be the end of humanity, I think A.I. is a bigger risk,” said Toby Ord, a researcher at Oxford University and author of “The Precipice: Existential Risk and the Future of Humanity.” Even Evan Hubinger, a researcher at Anthropic, wrote, “We really do earnestly believe A.I. could kill all humans!”

Climate activists now compete for a finite pool of political consideration. As diplomats and world leaders gather at the United Nations, Leah Stokes of University of California, Santa Barbara argued climate change is the more concrete danger, citing deadly heat waves in Europe and a glacier collapse in Nepal. “Unlike A.I., climate change’s existential threat is not hypothetical. It is killing people now,” she wrote.

Seth Baum of the Global Catastrophic Risk Institute described gradual A.I. catastrophe scenarios. For now, global warming’s risks are less hypothetical. Its science is long-established, and solutions such as solar energy and electric vehicles are proven.