Paleoclimatologist Jack Hall and his colleagues, Frank and Jason, are drilling for ice-core samples on the Larsen Ice Shelf for NOAA when the shelf breaks apart. When Jack later presents his findings on global warming at a United Nations conference in New Delhi, he fails to convince diplomats or US Vice President Raymond Becker. However, Professor Terry Rapson of the Hedland Climate Research Centre in Scotland believes in Jack’s theories. Shortly after, several buoys in the North Atlantic simultaneously register a sharp drop in ocean temperature, and Rapson concludes that melting polar ice has begun to disrupt the North Atlantic Current. He contacts Jack, whose paleoclimatologic weather model demonstrates how climate changes caused the first ice age. His team, including NASA meteorologist Janet Tokada, builds a forecast model based on Jack’s findings.
Around the world, violent weather causes widespread destruction; US President Blake authorizes the FAA to halt air traffic due to severe turbulence. On the International Space Station, three astronauts see a storm system spanning the Northern Hemisphere, which soon develops into three hurricane-like superstorms. The temperature of the eyes of the storms is −150 °F (−101 °C), flash freezing anything in their paths. The cells, located over Canada, Scotland, and Siberia, will affect all of their respective continents within days. During this time, tornadoes destroy Los Angeles.
In Manhattan, Jack’s son Sam learns about the worsening weather when he participates in an academic decathlon. Although Sam promises to be on the next train home, flooding quickly closes the subway and Grand Central Terminal, before a gigantic storm surge strikes New York City, flooding Manhattan. Sam and a large group of people seek shelter in the New York Public Library, and his teammate and love interest, Laura Chapman, accidentally cuts her leg while wading through the waist-deep water to higher ground. In Scotland, Rapson and his colleagues at the Hedland Centre die in the European superstorm.