Going, going, gone

This glacier pix, taken a few years ago on an Alaskan cruise by yours truly, may be but a memory by 2100 as glaciers are disappearing at an alarming rate based on an extensive study conducted over a 20 year period of scientists examining NASA satellite images with extreme precision. To whit.

Researchers in Canada, France, Switzerland, and Norway collected 20 years of satellite images taken from a special camera on a NASA satellite called Terra. The device, called ASTER, for Advanced Spaceborne Thermal Emission and Reflection Radiometer, took images of more than 210,000 glaciers around the world, photographing each with two separate lenses to create three-dimensional views of their surface features. The study excluded the massive ice sheets that cover Greenland and Antarctica, which are being studied by other teams of scientists.

The new analysis, published today in the journal Nature, found that between the years 2000 and 2004, glaciers lost 227 billion metric tons of ice per year. But between 2015 and 2019, this rate increased to 298 billion tons annually, a change the study’s authors attribute to warmer temperatures and increased precipitation. Taken together, that meltwater running down rivers and into oceans represents about one-fifth of the observed rise in sea levels over the past 20 years.

End result ...

And the problem isn’t just sea level rise, although that’s a significant issue, threatening the welfare of residents in coastal nations like Indonesia, Bangladesh, Panama, the Netherlands, and some parts of the United States. In some inland regions, millions of people depend on snowmelt for clean water; in years when there isn’t much snow, glaciers offer a backup water source. That’s especially true in parts of the Andes, the Himalayas, and Alaska. “They provide cool, plentiful water for many systems throughout the planet,” says Brian Menounos, professor of Earth sciences at the University of Northern British Columbia and an author on the new study. “Once those glaciers are gone, you don’t have that buffering capability.” 

Photograph: Brian Menounos

Click here to read the in-depth Nature article.