Climate records back to Viking times show the 20th century was unexceptional for rainfall and droughts despite assumptions that global warming would trigger more wet and dry extremes, a study showed on Wednesday. Stretching back 1,200 years, written accounts of climate indicated that variations in the extremes in the 20th century were less than in some past centuries. "Several other centuries show stronger and more widespread extremes," lead author Fredrik Ljungqvist of Stockholm University told Reuters. "We can't say it's more extreme now." Ljungqvist said many existing scientific models of climate change over-estimated assumptions that rising temperatures would make dry...