The world’s glaciers, past, present, and future.

As seen through the eyes of two of the most respected climate scientists, one American and one Swiss.

This month’s “This is not Cool” video features the looks-back and looks-ahead at the quickly changing glaciers of the planet.

Konrad “Koni” Steffen, glaciologist with the Swiss Federal Institute for Forest, Snow and Landscape Research, is a veteran of more than 25 years of research in Greenland. He points to “really increased” temperatures since around 2000. That warming came after a cooling of more than two degrees in the aftermath of the 1992 Mount Pinatubo eruption in the Philippines, Steffen explains. He says looking at Greenland only during the 1990s might have led to a conclusion that it was on a long-term cooling trend. But he talks of the “accelerated loss of ice” since 2000, including loss of 12 meters of ice depth at one research station. He is concerned about the ongoing annual loss of 350 gigatons of cubic ice in Greenland.

Ohio State climate scientist Lonnie Thompson, holder of the National Medal of Science, America’s highest award for a scientist, recounts his history of having recovered ice core samples from elevations of more than 23,000 feet … with the help of a team of yaks, and not just other scientists.

Thompson sees the world’s glaciers as an insurance policy: They accumulate snow in cold and wet periods and distribute it to thirsty populations in droughts and dry seasons. Thompson points to the “geopolitical hotspot” importance of the Indus River, which winds through China, Pakistan and India – each a nuclear countries and each dependent on an ongoing adequate flow of the Indus from glaciers now at risk of melting.

For Steffen, the problem is not that a one- or two-degree increase in global temperature will be catastrophic for humanity, but rather that “it will not stop there.” He is concerned that continued warming amounts to “a threat to humanity over the longer term.” He points to a need for the international community to reduce greenhouse gas emissions.

Thompson recounts having testified before a U.S. Senate committee in the early 70s and focusing then on “prevention” of severe climate change impacts.

“That time has come and gone,” he now says. “I think now it’s the mitigation, the adaptation, or the suffering.”