These annual rings have also shown that a period of six years, from 1568 to 1634 was not due to natural climate change, six decades of expansion of the subtropics, which pushed the desert climate in the north. Due to the expanding zone of hot and dry out & # 39; I, the Ottoman Empire in Turkey over the Ming Dynasty collapsed and the colony of Jamestown in Virginia was abandoned, believing Dr. Trouet said they were at least in part, related to the climate. "The way in society as well as politically drought & # 39 is part of the picture," she said.
Other sources – lacustrine deposits; ice core samples; coral; otolith or ear bones, fish; and even the shells of living and dead geoducks, large double snakeskin appendage – to add to the overall picture.
"We have divers suck ancient geoducks from the ocean floor," said Brian Black, a professor of dendrochronology, which also specializes in marine organisms. In combination with the long dead geoduck shells, the data can go back many thousands of years. Shells from the banks of Iceland's already back to 1000. "They show that in the past century is unprecedented warm," Dr. Black said.
Experts use the information shell ring, combined with the data of the tree rings to understand how climate drives ocean productivity and species of fish mix to help managers of fishing. "The key is to be aware of climate whiplash and what it means for fishing, "Dr. Black said.
Even the stars to give up some of its secrets trees. Sun and others Stars emit radiation It called galactic cosmic rays or G.C.R.s, which react in the atmosphere with nitrogen and carbon to change the level of 14, which is absorbed by all living beings, and it becomes tracer levels for cosmic rays.
Past G.C.R.s bursts from solar flares or other sources, mostly secret, but it attracted a lot of interest among researchers, as if they occur at the present time they can destroy communications satellites and other technologies. Event 744, first found in Japanese cedar and has since found worldwide, with & # 39 is the most powerful cosmic event beam loop recording tree is greater than the Carrington event solar storm in 1859, and, apparently, said the people living at the time.
"This year, as with the & # 39; appeared in the sky red crucifix, after sunset," was how the Anglo-Saxon Chronicle reported events in the middle of the eighth century.
It was most likely a huge solar flare. "This is unprecedented, there is nothing like that," said Charlotte Pearson, a professor of tree ring laboratory. "We're trying to work what's this and what causes it, but we're still not sure. "