?:reviewBody
|
-
Before the United Nations global climate summit kicked off on Nov. 29, an old meme starring climate activist and former Vice President Al Gore started to spread again online. The day Al Gore was born there were 130,000 glaciers on Earth, the post says. Today, only 130,000 remain. This post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook .) We fact-checked this back in 2019 . It was wrong then, and it’s wrong now. First, know that the standards for what qualifies as a glacier — a body of snow and ice that’s big enough in size and mass to move under its own weight — are not universal. The U.S. Geological Survey defines them according to the commonly accepted guidelines in which a body of ice has an area of at least 0.1 kilometers squared, or about 25 acres. William Colgan, a senior researcher with the Geological Survey of Denmark and Greenland, told PolitiFact in 2019 that the emerging global standard for defining a glacier is a minimum of 1 hectare , or 100 by 100 meters. That’s about 2.5 acres, or roughly equivalent to the grassy area inside a 400-meter running track . How many of those were there in 1948, the year Gore was born? We don’t know, Colgan said. Scientists use satellites to map glaciers and reliable satellite monitoring didn’t start until the mid 1980s. We do have estimates of the total number of glaciers today. According to the Randolph Glacier Inventory , Colgan said, there are 197,654 glaciers that are at least 1 hectare, or 0.01 square kilometers. That’s 67,654 more than the Facebook post says, not counting the thousands of glaciers that are missing, meaning they’re too small to be included in inventories. Walt Meier, a research scientist with the National Snow and Ice Data Center, told PolitiFact that inventories are always changing. The numbers could increase because more glaciers are getting mapped, he said. When we looked at this claim back in 2019, one database on the center’s website listed 306,865 glaciers. Bruce Raup, who works on the center’s Global Land Ice Measurements from Space initiative, told PolitiFact that approximately 300,000 is still a solid number in 2021. Some glaciers are being newly counted in regions that weren’t covered before, such as Iran, which has a small number of glaciers, Raup said. There were definitely more than 130,000 glaciers when Gore was born, he said — they just weren’t well-counted. He speculated the figure came from the World Glacier Inventory, and indeed, the inventory contains information for over 130,000 glaciers. But the inventory is just a snapshot of glacier distribution in the second half of the 20th century — it’s not comprehensive. The number of glaciers probably is actually growing over time, due to ice complexes shrinking and breaking apart into pieces Raup said. But our data aren’t good enough to document this well. We rate this post False.
(en)
|