Fire and Ice

Fruit Bats in the Hot Zone

A 1994 bestseller called The Hot Zone taught the world to fear Ebola. Now, scientists in Gabon think they know where the killer virus hides. It's inside Africa's fruit bats.

The scientists trapped and tested more than 1,000 animals in central Africa's Ebola-prone "hot zone." Of all the critters, only fruit bats harbored traces of the Ebola virus or showed evidence of an immune response. None of the bats had Ebola symptoms. They're just a biological hideout until the virus can get into a great ape--like a gorilla, a chimp, or a human.

When Ebola does get inside a human, there's a 50 to 90 percent chance that human will die, depending on which strain of Ebola got in. Reports of the nastiness of that death are exaggerated, but not by much.

At first, Ebola looks a lot like a bad case of the flu. You get a headache, muscle aches, and a raging fever, followed by nausea, vomiting, and diarrhea. But then things get a lot worse, as the virus ravages your liver, spleen, and kidneys.

If you're lucky, the systemic shock that follows doesn't kill you. If you're unlucky, it does. If you're very unlucky, you bleed uncontrollably before you die. Because the virus makes it hard for your blood to clot, about a third of Ebola victims start to hemorrhage, with massive bleeding inside and out. These victims never recover.

Fortunately, Ebola is rare. There have been fewer than 2,000 confirmed cases of the disease since its discovery in 1976. So while knowing the virus is there in African bats is reason to hug your kids tonight, it's no reason to panic.

Get the facts about Ebola from the
World Health Organization

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Ocean Currents in an Ice Age

Very, very cold

UK oceanographers say that the North Atlantic's warm water circulation system may be shutting down--with chilling implications for Europe.

Writing in the journal Nature, the researchers argue that the flow of warm water currents toward Europe has decreased by 30 percent in the last 50 years. The numbers--based on limited samples collected over five decades--aren't conclusive. But they do jibe with other recent research.

Why worry over warm water? If you saw the disaster flick The Day After Tomorrow, you have at least a fanciful idea of the answer. In the film, the Atlantic's Gulf Stream current shuts down, and--before you can ask "where's the science in this fiction?"--North America and Europe freeze solid.

Hollywood hyperbole aside, most scientists agree that a slowdown in the Atlantic's circulation system--which carries warm water from the tropics to the North Atlantic--really could lower Europe's temperatures by at least a few degrees. Many also think a full shutdown of the system was key to climate change during Earth's most recent glaciation, which lasted from about 115,000 to 10,000 years ago.

Many of us think of that period as the "Ice Age," but technically ice ages are recurrent climatic events that last millions of years. They're characterized by both glaciations (periods when the world's ice cover increases) and interglaciations (periods when it shrinks). Many scientists say we're still living in an ice age--though we're in the midst of an interglaciation, with glaciers melting away.

Actually, recent glacial melting could be hurting the North Atlantic circulation system. As more freshwater flows in from the north, less tropical water may come up from the south. So an overall warming trend could ironically lead to a frostier Europe. Of course, the local cooling trend would have to overcome the global warming trend for temperatures to go down. Such are the complexities of climatology.

Crack into more on ice ages at NOVA online

Sight of the Week:
Volcanic Fire Under Glacier Ice

Some 1,240 miles (2,000 kilometers) north of Antarctica is an island--Montagu Island--in the treacherous waters of the South Atlantic. This is no place for people, or penguins even. A glacier blankets the island land. And beneath the glacier, actually creating the island, is an active volcano.

Now scientists have satellite pictures of the volcano--Mount Belinda--spewing fiery lava down toward the icy sea. In just four weeks' time, the lava, traveling in a 100-yard (90-meter) flow, has released massive amounts of glacier-trapped water into the ocean and built up 50 new acres of land, as the molten rock slides into the water and cools. Scientists expect the changes to be dramatic. A decade ago, lava from a volcano in Iceland melted enough ice to create the second-largest flow of freshwater on the planet. At the time, only the Amazon River sent more freshwater toward the sea.

Scientist John Smellie, of the British Antarctic Survey, says, "How hot rock interacts with ice is so poorly understood. This opportunity to monitor a live eruption and see how it affects ice cover is priceless." Dr. Smellie also says he would "give his right arm to be down there right now." Fortunately, you don't have to give up body parts to see the fire-and-ice capades. Just click.

See fire and ice together in the South Seas

Michael Himick and Steve Sampson
December 6, 2005