Carbon dioxide usually gets most of the blame for global warming, but a dramatic increase in methane gas emissions is worrying scientists. Global warming is causing the world’s wetlands to produce more methane gas — which in turn is causing more global warming.

The Environmental Protection Agency has proposed tightening the standard for smog to protect human health. The result would be cleaner urban air. But because of a quirk of atmospheric chemistry, the pollution control measures could contribute to global warming.

Experts say there are only 350 whooping cranes left in the world. Operation Migration, a nonprofit organization, has been using ultralight aircraft to train the birds to migrate south for the winter. They have succeeded in boosting the species’ numbers in recent years.

Scientists attending the American Meteorological Society meeting in Atlanta say the field has weathered a storm created two months ago when hackers released e-mails from some prominent climate scientists. They say the e-mails revealed bad behavior by a small number of researchers and revealed some weaknesses in the scientific process. But the scientists say the e-mails did nothing to undermine the data showing that climate change is real.

From Britain to Beijing, folks have been shivering their way through a remarkably cold and snowy winter. Meanwhile, in parts of the Arctic, it’s downright balmy — though still below freezing. What’s behind all this unusual weather? It’s the Arctic Oscillation — and it’s gone negative.

Arctic-nesting shorebirds have some of the longest migrations in the world, traveling from the southern parts of Africa and South America. A new study reveals that they may go the distance for good reason: to avoid nest-raiding predators.

The first cargo planes with food, water, medical supplies, shelter and sniffer dogs headed to the Western Hemisphere’s poorest nation a day after the magnitude 7.0 quake flattened much of the capital of 2 million people. Haitian President Rene Preval says he believes the death toll stretches into the thousands.

The dead and injured lay in the streets of the Haitian capital Port-Au-Prince, as strong aftershocks rippled through the impoverished Caribbean nation Wednesday. A rough estimate of the number of casualties is impossible at this time, officials say.

The city of Tokyo has been waging a war on its crows for nearly a decade. Despite millions of dollars spent trying to reduce the corvine population, the number of crows is growing. The battle continues, with mixed results.

The Environmental Protection Agency released new smog rules this week in an effort to improve air quality around the nation. The tighter regulations have many suburban and rural areas concerned that they will not be able to comply, which means they may lose federal dollars.

The headwaters of the Middle East’s great rivers, the Euphrates and Tigris, originate in Turkey, which controls flow of the waters to the Arab world downstream. A three-year drought has devastated Syria and Iraq, fueling resentment against the Turks.

The Environmental Protection Agency proposed new, stricter smog standards Thursday, which would reverse Bush-era limits that contradicted scientists’ recommendations. Hundreds of counties now face government sanctions if they don’t meet the new pollution rules.

As red snapper populations along the southeast coast continue to decline, fisherman who depend on the stock are finding themselves at odds with the federal government and scientists who are working to overcoming years of overfishing.

A shut-down Polaroid film factory in Massachusetts has gotten new life manufacturing flexible solar panels. It’s just one example of a green industry that advocates say could use government support to spur job growth and help the environment.

A federal ban on fishing for red snapper, one of the most prized saltwater fish, is set to take effect Jan. 4 — part of an effort to bring back the species in the Atlantic Ocean. But coastal fishing towns that rely on business from anglers say the ban could take a huge economic toll.