On:

The Earth is threatened by ozone holes in the upper atmosphere that let in too many ultraviolet rays from the sun. One cause of the holes are ozone-eating clouds, made up of nitric acid and water, that are created by supercold air over the North and South Poles.

Scientists have long known about these clouds, but have just discovered the bands of frigid air in the stratosphere that help to create them. And as the Earth warms up, the stratosphere gets colder, making it an even better place to create ozone-eating clouds.
read more

On:

Fifteen years ago, Lake Manoun in the country of Cameroon exploded without warning, killing 34 people while nearby Lake Nyos has taken as many as 1700 lives. The villagers who live near the lakes still talk about the strange noises and the stench of sulfur that preceeded the explosions. Those who escaped remember the rumors about bombs and returning to find silent villages, with everyone dead.

U.S. scientists have discovered that the explosions are caused by carbon dioxide gas bubbling into the water through the cracks of old volcanoes, deep beneath the lake. Trapped by the weight of the water, the gas builds up into enormous amounts, until it finally blows. It kills anyone who happens to be near the lake by blocking oxygen to the lung, suffocating them.
read more

On:

Birds all over the world are facing ?a scramble to keep up with spring,? says leading bird biologist Don Thomas of the University of Sherbrooke in Canada.

As global warming increases, spring comes earlier. The problem is that birds can?t adjust to these kinds of weather changes, since they are genetically programmed to breed at a particular time of year, when the insects and seeds they need are supposed to be most plentiful. When birds breed early, they have to expend a lot more energy getting enough food to feed their babies.
read more