That is consistent with temperature proxy records found in nature, such as tree rings and ice cores.

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He was as active as a tree entombed in ice.

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But a court heard visitors were greeted by a muddy field, fairy lights dangling from a tree and a broken ice rink.

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It looked like a vista from an epic Russian romance tree branches coated with ice and frozen vineyards running along the hilly landscape.

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To find out how warm the earth was before that, climatologists have had to resort to indirect methods, such as measuring tree-rings, or counting the different isotopes of oxygen in layers of polar ice.

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After a short flight from Kathmandu to the mountain hamlet of Lukla, it took me 12 days to reach Base Camp, trekking 160km and climbing 10, 000 feet, hiking through dense forest, over a dozen suspension bridges, above the tree line and, finally, into a frozen landscape of ancient rock and glacial ice.

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