When I was a kid, one of my prized possessions was a globe. It was about the size of a basketball and had a waxy coating over its topographically bumpy outer skin. I'd spend hours looking at the deep greens of the Amazon in South America, the rich browns of the northern plains of America and the paler blues in the shallow waters of the Caribbean.
But no part of that globe fascinated me more than the Arctic, that amazing mass of white covering the top of the world. Being from New England, snow and ice per se didn't grab me - we had plenty of that in the winter. But a place where the snow and ice lasted all summer long? That was a miracle.
Today that miracle is on the brink of collapse.
To understand why, let's start with a few basics: Each year around March, Arctic sea ice begins its yearly melting period until the extent and volume of ice reach their annual minimums, usually sometime in mid-September. After that point, new ice forms until an annual maximum is reached, typically in March of the following year.
But as the planet has rapidly warmed, there has been much more melting than freezing each year. Consequently, the National Snow and Ice Data Center has reported that from 1979 to 2011, the monthly sea ice extent for September -- the month of the seasonal minimum -- has fallen at a rate of 12 percent per decade.
Scientists were shocked in September 2007 when the extent of sea ice over the Arctic Ocean plummeted to the lowest level ever recorded since satellites have monitored the ice. However, on Aug. 26 this year, the 2007 record was shattered. The ice extent fell to 4.10 million square kilometers (km2) -- compared to the 1979-2000 mean of 7.13 million km2. That is a reduction of more than 3 million square km -- 42 percent below the median and an area of ice equivalent to about one third of the entire land area of the United States.
And we haven't reached the bottom yet. We could see a couple more weeks of melting that would drop the record even further.
In this case, a video is worth a million words. Check out this excellent, but alarming, animation of the decline in sea ice volume from the NASA Earth Observatory and watch the globes of your youth dissolve before your eyes.
But summer Arctic ice is more than a spot on a map. It's vitally important to a whole range of life from tiny shrimp to large bowhead whales to local indigenous people. Ice loss has taken away hunting areas for southern populations of polar bears. As the ice disappears, both the bears and walruses are more often forced onto land where food is harder to come by and dangerous conditions like walrus stampedes have killed hundreds of mothers and calves. More and more Arctic species are being formally designated as threatened or endangered as a result of declining sea ice and other consequences of climate change. For residents of the Arctic, the shrinking ice cover has made traditional cross-ice travel routes more treacherous, and has led to increased erosion threatening coastal villages.
Less summer ice is not only a consequence of climate change, but it will also cause further warming: As the summer ice melts, the light colored ice which reflects the sun's rays back to space is replaced with dark water which absorbs more heat and warms the oceans further. And in a final warped twist, ice loss is creating opportunities to pull up more of the oil and gas that is fueling climate change.
Less obviously, the melting Arctic also is affecting our climate further south where the jet-stream and other aspects of atmospheric circulation in the mid-latitudes of the Northern Hemisphere are being disrupted. Against a backdrop of rising global temperatures, the changes in atmospheric circulation can sometimes allow warmer air to penetrate unusually far to the north, while elsewhere pushing colder air unusually far to the south. The circulation changes also can shift storm tracks and affect the frequency and severity of extreme weather, sometimes enhancing the persistence of weather patterns.
Over the last several years, the loss of Arctic ice has become one of the most prominent harbingers of climate change. The melting ice cap is an impact that we can clearly see and track over time. Sadly, today this is just one of several signs of dangerous climate change. Rising sea surface temperatures are supporting an increase in the tropical storms that strike the eastern U.S. Rising temperatures are intensifying costly droughts. Wildfires are growing larger; and fire seasons are longer and more destructive. Look no further than this summer as a glimpse of the future.
These are ominous signs that our climate system is destabilizing, but there have also been signs of hope in 2012. The governments of Australia, South Korea and South Africa joined New Zealand and the 27 countries of the European Union in deciding that companies must pay for the carbon pollution they produce. States and communities across America are preparing for rising sea levels and more disruptive weather patterns; and they are becoming more energy efficient and using more renewable energy rather than fossil fuels. Among the leaders is California, where a historic climate change law comes into full force in January 2013.
But on the national scene, politicians remain deafeningly silent about climate change.
The globe we knew as children is disappearing before our eyes. We need our politicians to have an adult conversation in America about these risks while we still have time.