As Oceans Rise, Scientists Work Toward Consensus

Behind the scenes of the U.N.'s latest climate-change report

The Slow Climb to Climate-Change Consensus 1

The Asahi Shimbun via Getty Images

A melting glacier near Qaanaaq, Greenland

As a glaciologist, Peter U. Clark has seen his fair share of icy cliffs plunging into the abyss. But four years ago, Mr. Clark, a geoscience professor at Oregon State University, went over a ledge like he'd never seen before: He agreed to help lead the next report from the United Nation's Intergovernmental Panel on Climate Change.

The group, known for issuing a definitive take on the science of global warming every six or seven years, had a dire need for