The debate over whether Earth is warming up is over. Now we're learning that climate disruptions feed off one another in accelerating spirals of destruction. Scientists fear we may be approaching the point of no return THE GREENHOUSE EFFECT Without the greenhouse effect, life on Earth would not be possible. Energy from the sun is absorbed by the planet and radiated back out as heat. Atmospheric gases like carbon dioxide trap that heat and keep it from leaking into space. That's what keeps us warm at night.
But as humans pour ever increasing amounts of greenhouse gases into the atmosphere, more of the sun's heat gets trapped, and the planet gets a fever BURNING FOSSIL FUELS RELEASES CARBON FUELING THE FIRE The amount of carbon dioxide in the atmosphere is climbing fast. Most of it comes from burning fuels for energy--gasoline in cars or coal for electricity, for example. The U.S., with less than 5% of the world's population, produces one-quarter of all greenhouse gases BURNING FORESTS REDUCES OXYGEN AND INCREASES DROUGHT SPREADING THE PAIN Deforestation, through clear-cutting or burning, sows havoc far beyond the affected area. The fires release still more carbon into the atmosphere, fewer plants survive to convert CO2 into oxygen, and scorched soil absorbs more heat and retains less water, increasing droughts •Plants take in CO2 •Fires release carbon •Less carbon absorbed •Soil dries out RISING TEMPERATURES MELT POLAR ICE AND PERMAFROST THAWING OUT The North Pole may be seasonally ice free by 2050. Melting permafrost will release vast amounts of trapped carbon into the air LESS ICE MEANS MORE HEAT WHICH MEANS LESS ICE SPEEDING UP Ice reflects nearly all the sun's energy that hits it. As the planet's ice melts, more of that energy is absorbed by Earth--which further raises the temperature. That, in turn, makes the remaining ice melt quicker •20% reflected by vegetation and dark soil •10% reflected by ocean water •90% reflected by ice MELTING ICE RAISES SEA LEVELS INUNDATING LOW COASTAL AREAS WASHING ASHORE The ice at the North Pole is floating, so as it melts, the sea level won't change much. But the massive ice sheets over Antarctica and Greenland are another story. If both melted completely, sea levels could rise nearly 220 ft. (72 m). That's a worst-case scenario. But the melting is accelerating, and sea levels are projected to rise gradually, threatening low-lying communities Sources: Intergovernmental Panel on Climate Change, Third Assessment Report; NOAA; NASA; National Snow and Ice Data Center; Carbon Dioxide Information Analysis Center; National Center for Atmospheric Research; U.S. Global Change Research Program; Goddard Institute for Space Studies