The Effect Global Warming Has on Icebergs
Oceans absorb a significant amount of the solar energy that reaches the Earth's surface because they cover 71 percent of the planet. Global warming affects oceans in several ways, one of the most serious being to cause icebergs and other sea ice to melt. Ironically, global warming has hastened the formation of icebergs while also increasing the rate at which they melt into the sea.
Icebergs are floating pieces of sea ice measuring at least 5 meters (16 feet) across and are typically found in the North Atlantic, near Greenland, and in the ocean surrounding Antarctica. Icebergs form when pieces of ice break free, or calve, from glaciers, ice sheets and ice caps. As global warming increases temperatures, more icebergs are calving from melting ice caps. Global warming is causing more icebergs to form, and these icebergs are melting at a faster rate than icebergs melted in the past.
Sea ice is melting rapidly, especially in the Arctic. Scientists at the University of Leeds have determined that global warming contributes to the loss of a tremendous amount of sea ice -- enough to equal 1.5 million icebergs the size of the Titanic every year. Melting icebergs and melting ice caps are causing sea levels to rise, in some areas significantly. Rising sea levels are expected to cause flooding and erosion in low-lying, coastal cities.
Why Archimedes Won't Help
Polar ice caps, or ice sheets formed over land, were once thought to be the only melting ice that could actually increase sea levels. Archimedes' principle states that any object floating in liquid is displacing its own weight of that liquid, so when floating ice melts, it changes form but does not change the amount of water in the ocean. The water contained in icebergs, however, is colder and less salty than seawater, so the two do not completely mix; the differences in density cause sea levels to rise slightly.
Polar Bear's Plight
Rising sea levels are just one of the consequences of melting icebergs. Global warming is altering the habitats of many Arctic animals. For example, the polar bear depends on icebergs as hunting platforms and resting places. As icebergs melt, polar bears have to swim farther between hunting platforms, expending more energy to find food. As a result, individual bears are suffering physically and struggling to reproduce. In 2008, polar bears were listed as a threatened species -- one likely to become endangered.
- New England Aquarium: Climate Change and the Oceans
- National Snow and Ice Data Center: Quick Facts on Icebergs
- Science Daily: Melting Icebergs in Polar Oceans Causing Sea Level Rise Globally, New Assessment Finds
- New England Aquarium: Climate Change Effects on Ocean Animals
- National Geographic News: Titanic Would Encounter More Icebergs Today?
Sarah Cairoli began her writing career in 2002, as a reporter for the "High Country Independent Press" in Belgrade, Mont. She then spent two years writing and editing for an online publishing company, and earned her master's degree in English from Northern Arizona University. Cairoli also writes for "Bozeman Magazine."