IF ALL THE ICE MELTED
Explore the world’s new coastlines if sea level rises 216 feet.
The maps here show the world as it is now, with only one difference: All the ice on land has melted and drained into the sea, raising it 216 feet and creating new shorelines for our continents and inland seas.
There are more than five million cubic miles of ice on Earth, and some scientists say it would take more than 5,000 years to melt it all. If we continue adding carbon to the atmosphere, we’ll very likely create an ice-free planet, with an average temperature of perhaps 80 degrees Fahrenheit instead of the current 58.
The Amazon Basin in the north and the Paraguay River Basin in the south would become Atlantic inlets, wiping out Buenos Aires, coastal Uruguay, and most of Paraguay. Mountainous stretches would survive along the Caribbean coast and in Central America.
Compared with other continents, Africa would lose less of its land to the ultimate sea-level catastrophe, but Earth’s rising heat might make much of it uninhabitable. In Egypt, Alexandria and Cairo will be swamped by the intruding Mediterranean.
London? A memory. Venice? Reclaimed by the Adriatic Sea. Thousands of years from now, in this catastrophic scenario, the Netherlands will have long since surrendered to the sea, and most of Denmark will be gone too. Meanwhile, the Mediterranean's expanding waters will also have swelled the Black and Caspian Seas.
Land now inhabited by 600 million Chinese would flood, as would all of Bangladesh, population 160 million, and much of coastal India. The inundation of the Mekong Delta would leave Cambodia's Cardamom Mountains stranded as an island.
Predominantly desert, the continent would gain a new inland sea—but it would lose much of the narrow coastal strip where four out of five Australians now live.
The East Antarctica ice sheet is so large—it contains four-fifths of all the ice on Earth—that it might seem unmeltable. It survived earlier warm periods intact. Lately it seems to be thickening slightly—because of global warming. The warmer atmosphere holds more water vapor, which falls as snow on East Antarctica. But even this behemoth is unlikely to survive a return to an Eocene Climate.
Like the Greenland ice sheet, the West Antarctic one was apparently much smaller during earlier warm periods. It's vulnerable because most of it sits on bedrock that's below sea level.The warming ocean is melting the floating ice sheet itself from below, causing it to collapse. Since 1992 it has averaged a net loss of 65 million metric tons of ice a year.
IF ALL THE ICE MELTED
AFTER THE OCEAN, ICE IS THE BIGGEST WATER RESERVOIR on the planet. There are more than five million cubic miles of it, and no one really knows how long it would take to melt it all. Probably more than 5,000 years, some scientists say. But if we burn all the Earth’s supply of coal, oil, and gas, adding some five trillion more tons of carbon to the atmosphere, we’ll create a very hot planet, with an average temperature of perhaps 80 degrees Fahrenheit instead of the current 58. Large swaths of it might become too hot for humans. And it would likely be ice free for the first time in more than 30 million years.
The last time Earth was free of ice was more than 34 million years ago, in the Eocene epoch. Alligators swam in Arctic swamps. But the planet slowly cooled as carbon dioxide rained from the air and was locked up in seafloor sediments. Continental ice sheets formed first in Antarctica, but over the past few million years they’ve repeatedly surged across northern continents too. We’re living in a warm interglacial period—20,000 years ago Chicago, New York, and London were buried under ice.
SOURCES: PHILIPPE HUYBRECHTS, VRIJE UNIVERSITEIT BRUSSEL; RICHARD S. WILLIAMS, JR., WOODS HOLE RESEARCH CENTER; JAMES C. ZACHOS, UNIVERSITY OF CALIFORNIA, SANTA CRUZ; USGS; NOAA, ETOPO1 BEDROCK, 1 ARC-MINUTE GLOBAL RELIEF MODEL COPYRIGHT Â© SEPTEMBER 2013 NATIONAL GEOGRAPHIC SOCIETY