Christopher Joyce

Small earthquakes in Ohio and Arkansas associated with hydraulic fracturing for gas have taken many people by surprise. Gas industry executives say there's no hard evidence that their activities are causing these quakes. But some scientists say it's certainly possible; in fact, people have been causing quakes for years.

In the 1960s, geologists realized that gold mines in South Africa had created small earthquakes. Caverns dug into the earth thousands of feet below the surface collapsed. The "pancake" effect caused quakes, in one case a magnitude 5.2 temblor.

In the world of violins, the names Stradivari and Guarneri are sacred. For three centuries, violin-makers and scientists have studied the instruments made by these Italian craftsmen. So far no one has figured out what makes their sound different. But a new study now suggests maybe they aren't so different after all.

OK, here's a test. Clip one is a musical phrase from Tchaikovsky's Violin Concerto in D Major. Clip two is the same phrase. The same musician plays both. But one is on a Stradivarius violin, the other on a violin made in 1980. See if you can tell the difference.

On Florida's Gulf coast Tuesday, there will be a celebrated homecoming. For a turtle. This is no ordinary turtle: Known as Johnny Vasco da Gama, after the 15th-century Portuguese explorer, it crossed the Atlantic twice — by sea and by air.

Johnny, as his human friends call him, is a critically endangered Kemp's ridley turtle. Only a few thousand of these sea-turtles exist, mostly in the Gulf of Mexico. Normally, they do not migrate across the Atlantic.

This year has something unpleasant in common with the years 1979 and 1986. In 1979, a nuclear reactor at Three Mile Island in Pennsylvania melted down. In 1986, the Soviet reactor at Chernobyl blew up and burned.

This year's meltdown occurred in Fukushima in Japan, and nuclear power isn't likely to be the same as a result.

Nuclear power had enjoyed 25 years of relative quiet, but the Fukushima accident reminded people that despite improvements in safety, nuclear plants could still go horribly wrong.

For some, though, nothing has changed much.

A European court ruled Wednesday that airlines flying into and out of European airports will have to pay a price for the carbon dioxide they emit when they burn jet fuel.

U.S. airlines, which had been fighting the idea in court, say the European Union is trying to force other countries to reduce carbon emissions. Europe currently limits carbon dioxide emissions from its major industries to curb global warming. The ruling cannot be appealed, and the decision likely to end the dispute.

The government organization charged with keeping nuclear power safe is having a meltdown. The Nuclear Regulatory Commission consists of five commissioners who direct the work of hundreds of nuclear engineers and other experts. They write the rules for how nuclear reactors operate.

Now four of those commissioners say the chairman of the NRC is a bully who's destroying their ability to do their job.

Some climate strategists are looking beyond the United Nations and the idea of remaking the energy economy — and toward the world's tropical forests.

The basic idea is to provide rich countries that emit lots of climate-warming gases another way to reduce their carbon footprint besides replacing or retrofitting factories and power plants. Instead, they could just pay poorer countries to keep their forests, or even expand them. Forests suck carbon out of the atmosphere. It's like paying someone to put carbon in a storehouse.

In archaeology, you get special bragging rights when you can lay claim to the oldest specimen of something.

Scientists in South Africa may now qualify for what they say is the world's oldest bed. Well, not a bed exactly, but more like a mattress made of grass.

What Lyn Wadley, an archaeologist at the University of Witswatersrand, found were mats of grass and sedge piled half an inch thick on the floor of a cavelike rock shelter in South Africa.

Second of a two-part series on California's climate policies. Read part 1.

Climate experts are exploring the concept of growing dense fields of weeds to help soak up carbon dioxide from the atmosphere.

Just over a year from now, California will begin enforcing a set of laws that limit emissions of greenhouse gases from factories, power plants and, eventually, from vehicles.

First of a two-part series on California's climate policies.

California is about to try a radical experiment. A little over a year from now, the state will limit the greenhouse gas emissions from factories and power plants, and, eventually, emissions from vehicles.

The U.S. Congress tried to pass a similar plan for the whole country but dropped the idea last year.

In 1977, a small crew of oceanographers traveled to the bottom of the Pacific Ocean and stumbled across a brand new form of life. The discovery was so unusual, it turned biology on its head and brought into question much of what scientists thought they knew about where life can form and what it needs in order to survive.

A scientist in Boston has been driving around the city measuring leaks in the gas mains. He's found a lot, and he wants the public to know where they are.

Gas leaks aren't uncommon, and gas companies spend a lot of time tracking them down and repairing them. But the scientific team says they're surprised at how many they've found, and what those leaks are doing to the health of the city's trees.

A law passed after the Exxon Valdez oil spill requires the government to assess the biological damage from big spills so fines can be fixed and damage paid for. The National Academy of Sciences has a report describing the methods and metrics of determining the "ecosystem services" that have been lost due to the BP oil spill in the Gulf of Mexico.

The planet may not feel any different today, but there are now 7 billion people on it, according to the United Nations.

That number will continue to rise, of course, and global incomes are likely to rise as well. That means more cars and computers, and bigger homes: the kinds of things Americans take for granted. It's that rise in consumption that has population experts worried.

Environmental hazards sicken or kill millions of people — soot or smog in the air, for example, or pollutants in drinking water. But the most dangerous stuff happens where the food is made — in peoples' kitchens.

That's according to the World Health Organization, which says that the smoke and gases from cooking fires in the world's poorest countries contribute to nearly two million deaths a year — that's more than malaria.

Apparently one of the earliest human instincts was to paint things, including bodies and cave walls. That's the conclusion from scientists who have discovered something remarkable in a South African cave — a tool kit for making paint. It looks to be the oldest evidence of paint-making.

Over in southern Africa 100,000 years ago, Homo sapiens was pretty new on the scene. A favorite hangout was a cave named Blombos near the Southern ocean.

The southwest African country of Namibia is trying a controversial approach to preserving its wildlife. Rural people control the animals and profit from them. But they have also found they must shoot some of the animals to cull the herds.

It's dawn and 40 degrees out. The air tastes of dust. Elias Neftali is behind the wheel of a truck, driving us through a long valley encircled by red-rock mountains. As a farmhand in the northwest desert of Namibia, Neftali used to shoot wild animals trying to eat his livestock.

Now he protects wild animals. And that can be scary.

"Oh my god, yep," he says. He tells me about a night he was sleeping in a bungalow out in the bush with some other wildlife guards.

Right now, armies of marketers, pollsters and social scientists are trying to figure out what Americans are thinking about — issues like global warming or Lady Gaga's latest outfit. And surveys are only so good: It's hard to get a big enough sample to be sure of the results. That's particularly vexing for social scientists who want a high standard of accuracy.

If you're into sexual chemistry, set an aging banana peel or apple core out on your kitchen counter, pull up a chair, and wait — for the fruit flies.

Those of us who eat beef can thank cattle for turning grass into something tastier. But grass is not always easy to come by, especially in Africa. And without grass, where's the beef?

The notion of "beauty" can mean many different things to artists. For the Brothers Quay — identical-twin filmmakers — it often means dimly lit black and white images of animated dolls, screws, cogs — any manner of inanimate object brought to life. They're so good at it that fellow filmmaker Terry Gilliam called the Quays' Street of Crocodiles one of the best animated films of all time.

The back rooms of museums are like your grandparents' attic, only the stuff is more exotic — things like fossilized jellyfish, dinosaur eggs, or mummified princes.

And if you look carefully, you'll find objects that once changed science but are now largely forgotten. You might call them Lost Treasures of Science. This is a story of one of those objects — a special bone that's part of a special skeleton.

A pair of fossils from a South African cave have scientists both excited and puzzled. Scientists say the fossils — an adult female and a juvenile — could be the long-sought transition between ape-like ancestors and the first humans.

The bones belong to creatures related to the famous Lucy fossil found in Ethiopia in the 1970s, but their owners lived more recently, just two million years ago.

The Tibetan Plateau is the world's highest place. It's four times the size of France and home to most of the world's highest mountains.

As you might expect, it's cold there. And it may be that the deep chill of the Tibetan Plateau played a role in the evolution of some of the world's most charismatic animals.

That's the belief of a scientist who discovered the skull of a woolly rhino on the Tibetan Plateau.

The year 2010 was a very bad one for Haiti. It started with an earthquake that killed over 300,000 people, mostly in the crowded capital of Port-au-Prince. After that, cholera originating in a U.N. camp broke out in a northern province and eventually spread to the city.

The light at the end of the tunnel for Libyans isn't just an end to the Moammar Gadhafi regime — it's also "light sweet crude."

Oil provides most of Libya's income. But the revolution there has strangled exports for months and starved the country of revenue and also temporarily bumped up world oil prices. So there's a lot of interest inside Libya and internationally in getting the country's oil wells up and running again.

The question is, when?

Drive through northern Pennsylvania and you'll see barns, cows, silos and drilling rigs perched on big, concrete pads.

Pennsylvania is at the center of a natural gas boom. New technology is pushing gas out of huge shale deposits underground. That's created jobs and wealth, but it may be damaging drinking water. That's because when you "frack," as hydraulic fracturing is called, you pump millions of gallons of fluids underground. That cracks the shale a mile deep and drives natural gas up to the surface — gas that otherwise could never be tapped.