Humans Push Earth to Tipping Point: Small Changes Could Create Dramatic Results

The term, "tipping point," became popular with the 2000 release of Malcolm Gladwell's book, "The Tipping Point: How Little Things Can Make a Big Difference." More recently, however, "tipping point" has become a warning cry from atmospheric scientists and geologists who see the Earth coming ever closer to damaging, irreversible and human-caused changes.

Simply defined, a tipping point marks the moment at which even a very small change leads to rapid and dramatic results. The difference between 33 degrees Fahrenheit and 32 degrees Fahrenheit, for example, is a tipping point for water. At the first temperature, water remains liquid. One degree lower, though, and water shifts to solid form ... it freezes.

Increasingly over the past few years, scientists are now identifying potential tipping points related to climate change. As humans continue pumping additional amounts of carbon dioxide -- a greenhouse gas -- into the air, average global temperatures have grown warmer, more sea ice and land ice have melted, and sea levels have little by little crept upward.

Such gradual changes might not continue into the future, however, scientists warn. As warming increases, so too does the risk of reaching one of several global tipping points that could lead to sudden and dramatic shifts.

"Society may be lulled into a false sense of security by smooth projections of global change," wrote a team of researchers just this week in an article published in the Proceedings of the National Academy of Sciences (PNAS).

Just last spring, researchers at NASA and the Columbia University Earth Institute reported that even moderate continued warming of the atmosphere could create a tipping point that would start an irreversible disintegration of Arctic sea ice and the West Antartic ice sheet.

Scientists last year observed signs that such changes were already in motion, as evidenced by rapid ice melting in Greenland and Antarctica, as well as by a record-low extent of Arctic summer sea ice that opened the Northwest Passage for the first time in recorded human history.