Post by coolplanet on Oct 24, 2013 14:48:05 GMT -5
Arctic Warming Unprecedented in Last 44,000 Years
Moss and other indicators suggest the current Arctic meltdown is unique in recent geologic history
www.scientificamerican.com/article.cfm?id=arctic-warming-unprecedented-in-last-44000-years
Excerpt:
…
The fact that certain ice caps did not melt during the Holocene Thermal Maximum, despite the extreme warmth at the time, suggests that today's unusual warming period can only be caused by greenhouse gases, Miller said.
"Nothing else out there can explain it," Miller said. Based on the Earth's current position in relation to the sun, the region should be cooling in the summer, not warming, he said.
…
Via radiocarbon dating of 365 vegetation samples, they determined that some of the newly exposed mosses from four of the ice caps were at least 40,000 years old. "We never expected to find plants that old," Miller said.
Their old age means that the ice caps entombing them had not melted for at least that long, staying colder than the present day through the peak warmth of the Holocene thermal maximum.
During that time, about 5,000 to 10,000 years ago, the eastern Canadian Arctic was closer to the sun in the summer than now, because of natural variabilities in Earth's orbit. The amount of solar radiation hitting the area was about 9 percent higher than now.
…
The findings are a "big deal" for showing that current temperatures are higher than the Holocene maximum, even though solar forcing was greater back then.
Moss and other indicators suggest the current Arctic meltdown is unique in recent geologic history
www.scientificamerican.com/article.cfm?id=arctic-warming-unprecedented-in-last-44000-years
Excerpt:
…
The fact that certain ice caps did not melt during the Holocene Thermal Maximum, despite the extreme warmth at the time, suggests that today's unusual warming period can only be caused by greenhouse gases, Miller said.
"Nothing else out there can explain it," Miller said. Based on the Earth's current position in relation to the sun, the region should be cooling in the summer, not warming, he said.
…
Via radiocarbon dating of 365 vegetation samples, they determined that some of the newly exposed mosses from four of the ice caps were at least 40,000 years old. "We never expected to find plants that old," Miller said.
Their old age means that the ice caps entombing them had not melted for at least that long, staying colder than the present day through the peak warmth of the Holocene thermal maximum.
During that time, about 5,000 to 10,000 years ago, the eastern Canadian Arctic was closer to the sun in the summer than now, because of natural variabilities in Earth's orbit. The amount of solar radiation hitting the area was about 9 percent higher than now.
…
The findings are a "big deal" for showing that current temperatures are higher than the Holocene maximum, even though solar forcing was greater back then.