Magazine Cover (And with sea ice vanishing, polar bears are starting to turn up drowned.)

From heat waves to storms to floods to fires to massive glacial melts, the global climate seems to be crashing around us.

The problem -- as scientists suspected but few others appreciated -- is that global climate systems are booby-trapped with tipping points and feedback loops, thresholds past which the slow creep of environmental decay gives way to sudden and self-perpetuating collapse. That's just what's happening now.

It's at the north and south poles -- where ice cover is crumbling to slush -- that the crisis is being felt the most acutely.

Late last year, for example, researchers analyzed data from Canadian and European satellites and found that the Greenland ice sheet is not only melting, but doing so faster and faster, with 53 cubic miles draining away into the sea last year alone, compared to 23 cubic miles in 1996.

One of the reasons the loss of the planet's ice cover is accelerating is that as the poles' bright white surface disappears it changes the relationship of the Earth and the sun. Polar ice is so reflective that 90 percent of the sunlight that strikes it simply bounces back into space, taking its energy with it. Ocean water does just the opposite, absorbing 90 percent of the light and heat it receives, meaning that each mile of ice that melts vanishes faster than the mile that preceded it.

This is what scientists call a feedback loop, and a similar one is also melting the frozen land called permafrost, much of which has been frozen -- since the end of last ice age in fact, or at least 8,000 years ago.

Sealed inside that cryonic time capsule are layers of decaying organic matter, thick with carbon, which itself can transform into CO2. In places like the southern boundary of Alaska the soil is now melting and softening.

As fast as global warming is changing the oceans and ice caps, it's having an even more immediate effect on land. Droughts are increasingly common as higher temperatures also bake moisture out of soil faster, causing dry regions that live at the margins to tip into full-blown crisis.

Wildfires in such sensitive regions as Indonesia, the western U.S. and even inland Alaska have been occurring with increased frequency as timberlands grow more parched. Those forests that don't succumb to fire can simply die from thirst.

With habitats crashing, the animals that call them home are succumbing too. In Alaska, salmon populations are faltering as melting permafrost pours mud into rivers, burying the gravel the fish need for spawning. Small animals such as bushy tailed rats, chipmunks and pinion mice are being chased upslope by rising temperatures, until they at last have no place to run.

And with sea ice vanishing, polar bears are starting to turn up drowned. "There will be no polar ice by 2060," says Larry Schweiger, president of the National Wildlife Federation. "Somewhere along that path, the polar bear drops out."

So much environmental collapse has at last awakened much of the world, particularly the 141 nations that have ratified the Kyoto treaty to reduce emissions. The Bush administration, however, has shown no willingness to address the warming crisis in a serious way and Congress has not been much more encouraging.

Sens. John McCain and Joe Lieberman have twice been unable to get even mild measures to limit carbon emissions through a recalcitrant Senate.

A 10-member House delegation did recently travel to Antarctica, Australia and New Zealand to meet with scientists studying climate change. "Of the 10 of us, only three were believers to begin with," says Rep. Sherman Boehlert of New York. "Every one of the others said this opened their eyes."

But lawmakers who still applaud themselves for recognizing global warming are hardly the same as lawmakers with the courage to reverse it, and increasingly, state and local governments are stepping forward.

The mayors of more than 200 cities have signed the U.S. Mayors Climate Protection Agreement, pledging, among other things, that they will meet the Kyoto goal of reducing greenhouse emissions in their own cities to 1990 levels by 2012. Nine northeastern states have established the Regional Greenhouse Gas Initiative for the purpose of developing a program to cap greenhouse gasses.

Polar Ice Caps Are Melting Faster Than Ever... More And More Land Is Being Devastated By Drought... Rising Waters Are Drowning Low-Lying Communities... By Any Measure, Earth Is At ... The Tipping Point

Photo Above: The photograph taken in 1928, above, shows how the Upsala Glacier, part of the South American Andes in Argentina, used to look. The ice on the Upsala Glacier today, shown in 2004 below, is retreating at least 180 ft. per year

No one can say exactly what it looks like when a planet takes ill, but it probably looks a lot like Earth. Never mind what you've heard about global warming as a slow-motion emergency that would take decades to play out. Suddenly and unexpectedly, the crisis is upon us.

It certainly looked that way last week as the atmospheric bomb that was Cyclone Larry--a Category 5 storm with wind bursts that reached 180 m.p.h.--exploded through northeastern Australia. It certainly looked that way last year as curtains of fire and dust turned the skies of Indonesia orange, thanks to drought-fueled blazes sweeping the island nation. It certainly looks that way as sections of ice the size of small states calve from the disintegrating Arctic and Antarctic. And it certainly looks that way as the sodden wreckage of New Orleans continues to molder, while the waters of the Atlantic gather themselves for a new hurricane season just two months away. Disasters have always been with us and surely always will be. But when they hit this hard and come this fast--when the emergency becomes commonplace--something has gone grievously wrong. That something is global warming.

The image of Earth as organism--famously dubbed Gaia by environmentalist James Lovelock-- has probably been overworked, but that's not to say the planet can't behave like a living thing, and these days, it's a living thing fighting a fever. From heat waves to storms to floods to fires to massive glacial melts, the global climate seems to be crashing around us. Scientists have been calling this shot for decades. This is precisely what they have been warning would happen if we continued pumping greenhouse gases into the atmosphere, trapping the heat that flows in from the sun and raising global temperatures.

Environmentalists and lawmakers spent years shouting at one another about whether the grim forecasts were true, but in the past five years or so, the serious debate has quietly ended. Global warming, even most skeptics have concluded, is the real deal, and human activity has been causing it. If there was any consolation, it was that the glacial pace of nature would give us decades or even centuries to sort out the problem.

But glaciers, it turns out, can move with surprising speed, and so can nature. What few people reckoned on was that global climate systems are booby-trapped with tipping points and feedback loops, thresholds past which the slow creep of environmental decay gives way to sudden and self-perpetuating collapse. Pump enough CO2 into the sky, and that last part per million of greenhouse gas behaves like the 212th degree Fahrenheit that turns a pot of hot water into a plume of billowing steam. Melt enough Greenland ice, and you reach the point at which you're not simply dripping meltwater into the sea but dumping whole glaciers. By one recent measure, several Greenland ice sheets have doubled their rate of slide, and just last week the journal Science published a study suggesting that by the end of the century, the world could be locked in to an eventual rise in sea levels of as much as 20 ft. Nature, it seems, has finally got a bellyful of us.

Issue # 26: Volume 3

Skywatch Editor's note: The following is a summary of this week's Time magazine cover story.

The climate is crashing, and global warming is to blame

Polar Ice Caps Are Melting Faster Than Ever... More And More Land Is Being Devastated By Drought... Rising Waters Are Drowning Low-Lying Communities... By Any Measure, Earth Is At ... The Tipping Point

From the Apr. 03, 2006 issue of TIME magazine