Straight ahead on "Our World" ... Global warming and the threat of mass extinction ... an Internet service clashes with amateur radio operators ... and protecting buildings when fire approaches ...
SABO: "And with the smoke and flames you couldn't tell whether my home was in there or not, and then when it cleared the house was still standing there and there was no damage to it whatsoever."
He's talking about firegel. Those stories, reaching for the stars on our Website of the Week, and more. I'm Art Chimes. Welcome to the 400th edition of VOA's science and technology magazine, "Our World."
A new survey from Yale University this week highlights Americans' concerns about climate change.
More than 70 percent of those surveyed are convinced that global warming is happening, and almost as many believe human activities are entirely or partly responsible. Almost two-thirds said global warming is an urgent threat requiring immediate and drastic action. On the other hand, they strongly oppose carbon taxes that would, for example, increase the price of gasoline.
Climate change is not just a story in today's headlines, though. It's part of the history of the planet. Due in part to the unprecedented scale of human industry, we may be seeing the climate changing faster than it has in the past, but Earth's history is full of warming and cooling periods.
In a new book, Under a Green Sky, author Peter Ward examines the link between earlier periods of climate change and mass extinctions that have wiped out as many as 90 percent of the species on the planet. VOA's Rosanne Skirble reports.
SKIRBLE: Peter Ward has spent a career studying fossils. He specializes in catastrophic mass extinctions from the earth's ancient past ? what scientists call the Big Five.
WARD: "And the Big Five are those [mass extinctions] that killed off at least 50 percent of the species on earth, and one of them, the Permian, may have killed off 90 percent of the species on earth."
SKIRBLE: Ward, a University of Washington paleontologist, details the causes and consequences of these events in Under a Green Sky. He says most scientists embrace the idea that a giant asteroid hit the earth around 65 million years ago, hastening the demise of the dinosaurs.
WARD: "We have all this dust going in the air. The earth goes through a global blackout. We have falling meteors coming back from the impact sites setting all the forests on fire. We have sulfur going into the atmosphere coming back as sulfuric acid, acidifying the ocean, acid rain in the lakes. There are just any number of kill mechanisms."
SKIRBLE: But asteroids do not explain the other mass extinctions. For that, Ward and others have found evidence in the fossil record that prolonged volcanic activity spewed huge amounts of carbon dioxide and other gases into the atmosphere.
WARD: "It was as if, at every one of these mass extinctions, there was short-term rapid increase in carbon dioxide, and CO2 does something that we know that it does, it causes rapid global warming. High C02 increases greenhouse temperatures on the planet, which it did."
SKIRBLE: Over thousands of years the spike in CO2 and the resulting worldwide heat wave had nasty consequences. Winds ceased, ocean currents died, and most marine life vanished from too much heat and too little oxygen.
WARD: "These warm anoxic oceans up at the surface produced blooms of hydrogen sulfide-producing bacteria. Enough of that went into the atmosphere to kill land animals and land plants and cause the ozone to disappear as well."
SKIRBLE: Records show that environmental change began to accelerate when atmospheric CO2 hit 1,000 parts per million. Today's levels are one third of that and rising.
WARD: "You look at all the dead species in the earth's past and it has happened! It happened through raising carbon dioxide. It will happen if we do not somehow control CO2 rise in the atmosphere.
SKIRBLE: But all is not hopeless. Ward does see some positive signs in the fight against global warming.
WARD: "Most people are now educated as to what it is and almost everyone knows that it has to do with carbon dioxide and that we have to slow that down. There is half the battle right there."
SKIRBLE: Ward is also encouraged that people are beginning to make changes in their daily lives and demanding action from their leaders. He hopes his book helps readers put the current state of the earth into historical perspective.