In September 2013 alone, Boulder, Colo., received more than half the precipitation it gets in an entire year. The water fell down mountainsides and roared through towns. Searching for an appropriate superlative, the National Weather Service called the storm "biblical." The Colorado floods followed Superstorm Sandy, which had drowned the Northeast coast the previous year and cost the nation $75 billion in damage. Was this the new normal, people asked -- and what was the risk of such storms returning? Researchers in the field of attribution science are trying to answer these questions and understand the extent to which climate change and such extreme events may be linked.