MAJOR CLIMATE CHANGE OCCURRED 5,200 YEARS AGO
EVIDENCE SUGGESTS THAT HISTORY COULD REPEAT ITSELFCOLUMBUS, Ohio -- Glaciologist Lonnie Thompson worries that he may have found clues that show history repeating itself, and if he is right, the result could have important implications to modern society.
Quelccaya ice cap. Annual accumulation
layers are clearly visible;
A professor of geological sciences at Ohio State and a researcher with the Byrd Polar Research Center, Thompson points to markers in numerous records suggesting that the climate was altered suddenly some 5,200 years ago with severe impacts.Evidence shows that around 5,200 years ago, solar output first dropped precipitously and then surged over a short period. It is this huge solar energy oscillation that Thompson believes may have triggered the climate change he sees in all those records.He points to perfectly preserved plants he discovered that recently emerged from the Quelccaya ice cap in the Peruvian Andes as that glacier retreats. This monstrous glacier, some 551 feet (168 meters) deep, has shown an exponentially increasing rate of retreat since his first observations in 1963.
The plants were carbon-dated to determine their age and tests indicated they had been buried by the ice for perhaps 5,200 years. That suggests that somehow, the climate had shifted suddenly and severely to capture the plants and preserve them until now.In 1991, hikers found the preserved body of a man trapped in an Alpine glacier and freed as it retreated. Later tests showed that the human – dubbed Oetzi – became trapped and died around 5,200 years ago.
Professor Lonnie Thompson
“Something happened back at this time and it was monumental,” Thompson said. “But it didn’t seem monumental to humans then because there were only approximately 250 million people occupying the planet, compared to the 6.4 billion we now have.
“The evidence clearly points back to this point in history and to some event that occurred. It also points to similar changes occurring in today’s climate as well,” he said.“To me, these are things we really need to be concerned about.” The impact of a climate change of that magnitude on a modern world would be tremendous, he said. Seventy percent of the population lives in the world’s tropics and major climate changes would directly impact most of them. Thompson believes that the 5,200-year old event may have been caused by a dramatic fluctuation in solar energy reaching the earth. Scientists know that a historic global cooling called the Little Ice Age, from 1450 to 1850 A.D., coincided with two periods of decreased solar activity. Evidence shows that around 5,200 years ago, solar output first dropped precipitously and then surged over a short period. It is this huge solar energy oscillation that Thompson believes may have triggered the climate change he sees in all those records. “The climate system is remarkably sensitive to natural variability,” he said. “It’s likely that it is equally sensitive to effects brought on by human activity, changes like increased greenhouse gases, altered land-use policies and fossil-fuel dependence. “Any prudent person would agree that we don’t yet understand the complexities with the climate system and, since we don’t, we should be extremely cautious in how much we ‘tweak’ the system,” he said. “The evidence is clear that a major climate change is underway.”
Source: Ohio State University Research
Contact: Lonnie Thompson, (614) 292-6652;firstname.lastname@example.orgWritten by Earle Holland, (614) 292-8384; Holland.email@example.com.