Damage done: The Deepwater Horizon incident may have been the worst oil spill in U.S. history, but it pales in comparison to the ongoing catastrophe that has afflicted Nigeria's Niger River Delta over the last five decades. As many as 546 million gallons of oil are believed to have spilled since oil exploration began in this region -- the equivalent of an Exxon Valdez spill every year.

There are around 2,000 official spill sites in the region, some of them decades old.
Oil companies operating in the region blame thieves and sabotage for the majority of the spills, though local activists say aging equipment and lax safety are the cause of many of them. The number of severity of the spills may actually increase in coming years as the industry moves into more remote and difficult terrain in the delta.

It's not just the spilled oil that can be dangerous. Pipeline explosions, like in the one that killed more than 100 people outside Lagos in 2008, are increasingly frequent as well.

CHINA

Disaster: Coal fires

Going since: 1962

Damage done: China's recent industrial growth depends heavily on coal -- the source of 70 percent of the country's energy -- a major reason why it recently became the world's largest carbon emitter. The country's mining sector is also extremely dangerous, killing as many as 13 miners every day. But nowhere is the danger of China's out-of-control coal addiction more evident than in the 62 raging underground coal fires that have burned in Inner Mongolia since the early 1960s.

Covering an area more than 3,000 miles long, China's northern coal fires are estimated to destroy as many as 20 million tons of coal per year, more than the entire annual production of Germany. According to some estimates, these fires could be the cause of up to 2 to 3 percent of the world's carbon emissions from burning fossil fuels. A new initiative by the Inner Mongolia Autonomous Region aims to put half the fires out by 2012.

Inner Mongolia's coal fires may be the most severe, but they are hardly unique. An underground fire in Centralia, Pa., begun the same year as many of China's, is also still burning.

HAITI

Disaster: Deforestation

Going since: 1492

Damage done: Haiti and the Dominican Republic share an island, as well as similar geographic and climate conditions. So why do severe storms and hurricanes -- not to mention earthquakes -- only cause horrific human tragedy on the Haitian side? One large reason is the almost complete destruction of Haiti's trees.

When explorer Christopher Columbus first landed in what was then dubbed Hispañola, around three-fourths of it was covered in trees. Today, 98 percent of its forests are gone -- one of the worst cases of deforestation in human history.

The main culprit is charcoal, by far the country's most popular fuel source, which consumes up to 30 million trees per year. The Dominican Republic has banned cutting down trees for charcoal and subsidized propane as a substitute, and the contrast can be seen in satellite photographs of the border.

Without roots to hold the soil together, hurricanes and earthquakes are much more likely to case deadly landslides. The erosion of high-quality topsoil has also devastated Haiti's agricultural sector, exacerbating its endemic poverty.

The list of challenges confronting Haiti following this year's earthquake is long and daunting, but if the country is ever going to stand a fighting chance, what it needs more than anything else is more trees.

UZBEKISTAN/KAZAKHSTAN

Disaster: The shrinking of the Aral Sea

Going since: The 1960s

Damage done: Straddling the border of Uzbekistan and Kazakhstan, the Aral Sea was once the world's fourth-largest inland water body and home to at least 20 species of fish and a thriving coastal economy in the surrounding towns. In the early 1960s, the Soviet government built more than 45 dams and 20,000 miles of canals in an effort to create a cotton industry on the desert plains of Uzbekistan, depriving the sea of its main sources.

Over the next three decades, the sea shrank to two-fifths its original size, turning fishing villages into barren desert outposts. Thanks to the high salt content in the remaining water, all 20 fish species are now extinct. Drinking water supplies in the area are dangerously low and the ground contains dangerous pesticides from the cotton farms. When the wind sweeps across the now-dry sea bed, it spreads up to 75 million tons of toxic dust and salt across Central Asia every year.

Thankfully, dams constructed in the last decade on the Kazakh side seem to be leading to a partial recovery. The Northern Aral's surface span has grown by 20 percent and fish and bird species are starting to return. The Southern Aral, however, still remains a shadow of its former self.

PACIFIC OCEAN

Disaster: The Eastern Garbage Patch

Going since: Discovered in 1997

Damage done: Somewhere between California and Hawaii lies the world's largest garbage dump -- a massive soup of plastic and debris one-and-a-half times the size of the United States and 100 feet deep. The "patch" is the product of the North Pacific Gyre, a loop of currents that picks up trash from the West Coast of the United States and East Asia and funnels it into an endless loop in the North Pacific.

Within the patch, pieces of plastic outweigh zooplankton by a factor of 6 to 1, and are often mistaken by fish and birds for food. Chemicals from the plastic can also make their way into the food chain, including fish consumed by humans.

The patch is the most widely publicized example, but this is a global problem. According to the U.N. Environment Program the world's oceans contain 46,000 pieces of plastic per square mile. These plastics are responsible for the deaths of more than a million seabirds and 100,000 marine mammals every year.