As the U.N. celebrates the International Year of Forests to promote forest conservation, thousands of square miles of the planet's woodlands are destroyed each year to make way for sprawling suburbs, palm oil and soybean plantations, cattle ranches and farms. Experts say deforestation threatens a delicate balance in which forests act as Earth's lungs: absorbing carbon dioxide -- the biggest contributor to climate change -- and expelling oxygen. Now, scientists say, deforestation could soon release enormous amounts of carbon gases stored in the trees, undergrowth and melting permafrost. Such a "carbon bomb," experts warn, would exacerbate climate change, triggering even more deforestation and threatening a variety of crucial environmental functions forests perform, such as air and water purification, erosion prevention, rain production and the creation of fuel, shelter, medicines and endangered species habitat. Efforts by world leaders to slow deforestation are showing progress, but scientists say more aggressive action is needed.

Doug Struck covered the environment and climate change from locations around the globe during 30 years at The Washington Post and The Baltimore Sun, from the Northwest Passage, Greenland's ice shelf and Canada's boreal forests to glaciers in Peru and deserts in Sudan. He also served as a bureau chief in the Middle East, Tokyo and Toronto and covered wars in Iraq, Afghanistan, Lebanon, the West Bank and other conflict zones. Struck is now associate chairman of the Journalism Department at Emerson College in Boston.